Baolin Wang [Wed, 8 Sep 2021 22:18:03 +0000 (15:18 -0700)]
mm: migrate: fix the incorrect function name in comments
since commit a98a2f0c8ce1 ("mm/rmap: split migration into its own
function"), the migration ptes establishment has been split into a
separate try_to_migrate() function, thus update the related comments.
Baolin Wang [Wed, 8 Sep 2021 22:18:01 +0000 (15:18 -0700)]
mm: migrate: introduce a local variable to get the number of pages
Use thp_nr_pages() instead of compound_nr() to get the number of pages for
THP page, meanwhile introducing a local variable 'nr_pages' to avoid
getting the number of pages repeatedly.
mm/vmstat: protect per cpu variables with preempt disable on RT
Disable preemption on -RT for the vmstat code. On vanila the code runs in
IRQ-off regions while on -RT it may not when stats are updated under a
local_lock. "preempt_disable" ensures that the same resources is not
updated in parallel due to preemption.
This patch differs from the preempt-rt version where __count_vm_event and
__count_vm_events are also protected. The counters are explicitly
"allowed to be to be racy" so there is no need to protect them from
preemption. Only the accurate page stats that are updated by a
read-modify-write need protection. This patch also differs in that a
preempt_[en|dis]able_rt helper is not used. As vmstat is the only user of
the helper, it was suggested that it be open-coded in vmstat.c instead of
risking the helper being used in unnecessary contexts.
Subsystems affected by this patch series: mm (memory-hotplug, rmap,
ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
selftests, ipc, and scripts"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (94 commits)
scripts: check_extable: fix typo in user error message
mm/workingset: correct kernel-doc notations
ipc: replace costly bailout check in sysvipc_find_ipc()
selftests/memfd: remove unused variable
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
configs: remove the obsolete CONFIG_INPUT_POLLDEV
prctl: allow to setup brk for et_dyn executables
pid: cleanup the stale comment mentioning pidmap_init().
kernel/fork.c: unexport get_{mm,task}_exe_file
coredump: fix memleak in dump_vma_snapshot()
fs/coredump.c: log if a core dump is aborted due to changed file permissions
nilfs2: use refcount_dec_and_lock() to fix potential UAF
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
trap: cleanup trap_init()
init: move usermodehelper_enable() to populate_rootfs()
...
Merge tag 'mm-slub-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux
Pull SLUB updates from Vlastimil Babka:
"SLUB: reduce irq disabled scope and make it RT compatible
This series was initially inspired by Mel's pcplist local_lock
rewrite, and also interest to better understand SLUB's locking and the
new primitives and RT variants and implications. It makes SLUB
compatible with PREEMPT_RT and generally more preemption-friendly,
apparently without significant regressions, as the fast paths are not
affected.
The main changes to SLUB by this series:
- irq disabling is now only done for minimum amount of time needed to
protect the strict kmem_cache_cpu fields, and as part of spin lock,
local lock and bit lock operations to make them irq-safe
- SLUB is fully PREEMPT_RT compatible
The series should now be sufficiently tested in both RT and !RT
configs, mainly thanks to Mike.
The RFC/v1 version also got basic performance screening by Mel that
didn't show major regressions. Mike's testing with hackbench of v2 on
!RT reported negligible differences [6]:
RT configs showed some throughput regressions, but that's expected
tradeoff for the preemption improvements through the RT mutex. It
didn't prevent the v2 to be incorporated to the 5.13 RT tree [7],
leading to testing exposure and bugfixes.
Before the series, SLUB is lockless in both allocation and free fast
paths, but elsewhere, it's disabling irqs for considerable periods of
time - especially in allocation slowpath and the bulk allocation,
where IRQs are re-enabled only when a new page from the page allocator
is needed, and the context allows blocking. The irq disabled sections
can then include deactivate_slab() which walks a full freelist and
frees the slab back to page allocator or unfreeze_partials() going
through a list of percpu partial slabs. The RT tree currently has some
patches mitigating these, but we can do much better in mainline too.
Patches 1-6 are straightforward improvements or cleanups that could
exist outside of this series too, but are prerequsities.
Patches 7-9 are also preparatory code changes without functional
changes, but not so useful without the rest of the series.
Patch 10 simplifies the fast paths on systems with preemption, based
on (hopefully correct) observation that the current loops to verify
tid are unnecessary.
Patches 11-20 focus on reducing irq disabled scope in the allocation
slowpath:
- patch 11 moves disabling of irqs into ___slab_alloc() from its
callers, which are the allocation slowpath, and bulk allocation.
Instead these callers only disable preemption to stabilize the cpu.
- The following patches then gradually reduce the scope of disabled
irqs in ___slab_alloc() and the functions called from there. As of
patch 14, the re-enabling of irqs based on gfp flags before calling
the page allocator is removed from allocate_slab(). As of patch 17,
it's possible to reach the page allocator (in case of existing
slabs depleted) without disabling and re-enabling irqs a single
time.
Pathces 21-26 reduce the scope of disabled irqs in functions related
to unfreezing percpu partial slab.
Patch 27 is preparatory. Patch 28 is adopted from the RT tree and
converts the flushing of percpu slabs on all cpus from using IPI to
workqueue, so that the processing isn't happening with irqs disabled
in the IPI handler. The flushing is not performance critical so it
should be acceptable.
Patch 29 also comes from RT tree and makes object_map_lock RT
compatible.
Patch 30 make slab_lock irq-safe on RT where we cannot rely on having
irq disabled from the list_lock spin lock usage.
Patch 31 changes kmem_cache_cpu->partial handling in put_cpu_partial()
from cmpxchg loop to a short irq disabled section, which is used by
all other code modifying the field. This addresses a theoretical race
scenario pointed out by Jann, and makes the critical section safe wrt
with RT local_lock semantics after the conversion in patch 35.
Patch 32 changes preempt disable to migrate disable, so that the
nested list_lock spinlock is safe to take on RT. Because
migrate_disable() is a function call even on !RT, a small set of
private wrappers is introduced to keep using the cheaper
preempt_disable() on !PREEMPT_RT configurations. As of this patch,
SLUB should be already compatible with RT's lock semantics.
Finally, patch 33 changes irq disabled sections that protect
kmem_cache_cpu fields in the slow paths, with a local lock. However on
PREEMPT_RT it means the lockless fast paths can now preempt slow paths
which don't expect that, so the local lock has to be taken also in the
fast paths and they are no longer lockless. RT folks seem to not mind
this tradeoff. The patch also updates the locking documentation in the
file's comment"
Mike Galbraith and Mel Gorman verified that their earlier testing
observations still hold for the final series:
Link: https://lore.kernel.org/lkml/89ba4f783114520c167cc915ba949ad2c04d6790.camel@gmx.de/ Link: https://lore.kernel.org/lkml/20210907082010.GB3959@techsingularity.net/
* tag 'mm-slub-5.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux: (33 commits)
mm, slub: convert kmem_cpu_slab protection to local_lock
mm, slub: use migrate_disable() on PREEMPT_RT
mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg
mm, slub: make slab_lock() disable irqs with PREEMPT_RT
mm: slub: make object_map_lock a raw_spinlock_t
mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context
mm, slab: split out the cpu offline variant of flush_slab()
mm, slub: don't disable irqs in slub_cpu_dead()
mm, slub: only disable irq with spin_lock in __unfreeze_partials()
mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing
mm, slub: detach whole partial list at once in unfreeze_partials()
mm, slub: discard slabs in unfreeze_partials() without irqs disabled
mm, slub: move irq control into unfreeze_partials()
mm, slub: call deactivate_slab() without disabling irqs
mm, slub: make locking in deactivate_slab() irq-safe
mm, slub: move reset of c->page and freelist out of deactivate_slab()
mm, slub: stop disabling irqs around get_partial()
mm, slub: check new pages with restored irqs
mm, slub: validate slab from partial list or page allocator before making it cpu slab
mm, slub: restore irqs around calling new_slab()
...
Randy Dunlap [Wed, 8 Sep 2021 03:00:56 +0000 (20:00 -0700)]
mm/workingset: correct kernel-doc notations
Use the documented kernel-doc format to prevent kernel-doc warnings.
mm/workingset.c:256: warning: No description found for return value of 'workingset_eviction'
mm/workingset.c:285: warning: Function parameter or member 'folio' not described in 'workingset_refault'
mm/workingset.c:285: warning: Excess function parameter 'page' description in 'workingset_refault'
Link: https://lkml.kernel.org/r/20210808203153.10678-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rafael Aquini [Wed, 8 Sep 2021 03:00:53 +0000 (20:00 -0700)]
ipc: replace costly bailout check in sysvipc_find_ipc()
sysvipc_find_ipc() was left with a costly way to check if the offset
position fed to it is bigger than the total number of IPC IDs in use. So
much so that the time it takes to iterate over /proc/sysvipc/* files grows
exponentially for a custom benchmark that creates "N" SYSV shm segments
and then times the read of /proc/sysvipc/shm (milliseconds):
12 msecs to read 1024 segs from /proc/sysvipc/shm
18 msecs to read 2048 segs from /proc/sysvipc/shm
65 msecs to read 4096 segs from /proc/sysvipc/shm
325 msecs to read 8192 segs from /proc/sysvipc/shm
1303 msecs to read 16384 segs from /proc/sysvipc/shm
5182 msecs to read 32768 segs from /proc/sysvipc/shm
The root problem lies with the loop that computes the total amount of ids
in use to check if the "pos" feeded to sysvipc_find_ipc() grew bigger than
"ids->in_use". That is a quite inneficient way to get to the maximum
index in the id lookup table, specially when that value is already
provided by struct ipc_ids.max_idx.
This patch follows up on the optimization introduced via commit 15df03c879836 ("sysvipc: make get_maxid O(1) again") and gets rid of the
aforementioned costly loop replacing it by a simpler checkpoint based on
ipc_get_maxidx() returned value, which allows for a smooth linear increase
in time complexity for the same custom benchmark:
2 msecs to read 1024 segs from /proc/sysvipc/shm
2 msecs to read 2048 segs from /proc/sysvipc/shm
4 msecs to read 4096 segs from /proc/sysvipc/shm
9 msecs to read 8192 segs from /proc/sysvipc/shm
19 msecs to read 16384 segs from /proc/sysvipc/shm
39 msecs to read 32768 segs from /proc/sysvipc/shm
Link: https://lkml.kernel.org/r/20210809203554.1562989-1-aquini@redhat.com Signed-off-by: Rafael Aquini <aquini@redhat.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Manfred Spraul <manfred@colorfullife.com> Cc: Waiman Long <llong@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
Commit 05a4a9527931 ("kernel/watchdog: split up config options") adds a
new config HARDLOCKUP_DETECTOR, which selects the non-existing config
HARDLOCKUP_DETECTOR_ARCH.
This CONFIG option was removed in commit 278b13ce3a89 ("Input: remove
input_polled_dev implementation") so there's no point to keep it in
defconfigs any longer.
Keno Fischer reported that when a binray loaded via ld-linux-x the
prctl(PR_SET_MM_MAP) doesn't allow to setup brk value because it lays
before mm:end_data.
This of course prevent criu from restoring such programs. Looking into
how kernel operates with brk/start_brk inside brk() syscall I don't see
any problem if we allow to setup brk/start_brk without checking for
end_data. Even if someone pass some weird address here on a purpose then
the worst possible result will be an unexpected unmapping of existing vma
(own vma, since prctl works with the callers memory) but test for
RLIMIT_DATA is still valid and a user won't be able to gain more memory in
case of expanding VMAs via new values shipped with prctl call.
Link: https://lkml.kernel.org/r/20210121221207.GB2174@grain Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec") Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Reported-by: Keno Fischer <keno@juliacomputing.com> Acked-by: Andrey Vagin <avagin@gmail.com> Tested-by: Andrey Vagin <avagin@gmail.com> Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pid: cleanup the stale comment mentioning pidmap_init().
pidmap_init() has already been replaced with pid_idr_init() in the commit 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API").
Cleanup the stale comment which still mentions it.
fs/coredump.c: log if a core dump is aborted due to changed file permissions
For obvious security reasons, a core dump is aborted if the filesystem
cannot preserve ownership or permissions of the dump file.
This affects filesystems like e.g. vfat, but also something like a 9pfs
share in a Qemu test setup, running as a regular user, depending on the
security model used. In those cases, the result is an empty core file and
a confused user.
To hopefully save other people a lot of time figuring out the cause, this
patch adds a simple log message for those specific cases.
[akpm@linux-foundation.org: s/|%s/%s/ in printk text]
Zhen Lei [Wed, 8 Sep 2021 03:00:26 +0000 (20:00 -0700)]
nilfs2: use refcount_dec_and_lock() to fix potential UAF
When the refcount is decreased to 0, the resource reclamation branch is
entered. Before CPU0 reaches the race point (1), CPU1 may obtain the
spinlock and traverse the rbtree to find 'root', see
nilfs_lookup_root().
Although CPU1 will call refcount_inc() to increase the refcount, it is
obviously too late. CPU0 will release 'root' directly, CPU1 then
accesses 'root' and triggers UAF.
Use refcount_dec_and_lock() to ensure that both the operations of
decrease refcount to 0 and link deletion are lock protected eliminates
this risk.
Nanyong Sun [Wed, 8 Sep 2021 03:00:23 +0000 (20:00 -0700)]
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del(). See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".
Nanyong Sun [Wed, 8 Sep 2021 03:00:21 +0000 (20:00 -0700)]
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
If kobject_init_and_add returns with error, kobject_put() is needed here
to avoid memory leak, because kobject_init_and_add may return error
without freeing the memory associated with the kobject it allocated.
Nanyong Sun [Wed, 8 Sep 2021 03:00:18 +0000 (20:00 -0700)]
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
The kobject_put() should be used to cleanup the memory associated with the
kobject instead of kobject_del. See the section "Kobject removal" of
"Documentation/core-api/kobject.rst".
Nanyong Sun [Wed, 8 Sep 2021 03:00:15 +0000 (20:00 -0700)]
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
If kobject_init_and_add return with error, kobject_put() is needed here to
avoid memory leak, because kobject_init_and_add may return error without
freeing the memory associated with the kobject it allocated.
Nanyong Sun [Wed, 8 Sep 2021 03:00:12 +0000 (20:00 -0700)]
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
In nilfs_##name##_attr_release, kobj->parent should not be referenced
because it is a NULL pointer. The release() method of kobject is always
called in kobject_put(kobj), in the implementation of kobject_put(), the
kobj->parent will be assigned as NULL before call the release() method.
So just use kobj to get the subgroups, which is more efficient and can fix
a NULL pointer reference problem.
Nanyong Sun [Wed, 8 Sep 2021 03:00:09 +0000 (20:00 -0700)]
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
Patch series "nilfs2: fix incorrect usage of kobject".
This patchset from Nanyong Sun fixes memory leak issues and a NULL
pointer dereference issue caused by incorrect usage of kboject in nilfs2
sysfs implementation.
If kobject_init_and_add return with error, then the cleanup of kobject
is needed because memory may be allocated in kobject_init_and_add
without freeing.
And the place of cleanup_dev_kobject should use kobject_put to free the
memory associated with the kobject. As the section "Kobject removal" of
"Documentation/core-api/kobject.rst" says, kobject_del() just makes the
kobject "invisible", but it is not cleaned up. And no more cleanup will
do after cleanup_dev_kobject, so kobject_put is needed here.
Kefeng Wang [Wed, 8 Sep 2021 03:16:06 +0000 (20:16 -0700)]
trap: cleanup trap_init()
There are some empty trap_init() definitions in different ARCHs, Introduce
a new weak trap_init() function to clean them up.
Link: https://lkml.kernel.org/r/20210812123602.76356-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm32] Acked-by: Vineet Gupta [arc] Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc] Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Stafford Horne <shorne@gmail.com> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Helge Deller <deller@gmx.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <palmerdabbelt@google.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
init: move usermodehelper_enable() to populate_rootfs()
Currently, usermodehelper is enabled right before PID1 starts going
through the initcalls. However, any call of a usermodehelper from a
pure_, core_, postcore_, arch_, subsys_ or fs_ initcall is futile, as
there is no filesystem contents yet.
Up until commit e7cb072eb988 ("init/initramfs.c: do unpacking
asynchronously"), such calls, whether via some request_module(), a
legacy uevent "/sbin/hotplug" notification or something else, would
just fail silently with (presumably) -ENOENT from
kernel_execve(). However, that commit introduced the
wait_for_initramfs() synchronization hook which must be called from
the usermodehelper exec path right before the kernel_execve, in order
that request_module() et al done from *after* rootfs_initcall()
time (i.e. device_ and late_ initcalls) would continue to find a
populated initramfs as they used to.
Any call of wait_for_initramfs() done before the unpacking has been
scheduled (i.e. before rootfs_initcall time) must just return
immediately [and let the caller find an empty file system] in order
not to deadlock the machine. I mistakenly thought, and my limited
testing confirmed, that there were no such calls, so I added a
pr_warn_once() in wait_for_initramfs(). It turns out that one can
indeed hit request_module() as well as kobject_uevent_env() during
those early init calls, leading to a user-visible warning in the
kernel log emitted consistently for certain configurations.
We could just remove the pr_warn_once(), but I think it's better to
postpone enabling the usermodehelper framework until there is at least
some chance of finding the executable. That is also a little more
efficient in that a lot of work done in umh.c will be elided. However,
it does change the error seen by those early callers from -ENOENT to
-EBUSY, so there is a risk of a regression if any caller care about
the exact error value.
Link: https://lkml.kernel.org/r/20210728134638.329060-1-linux@rasmusvillemoes.dk Fixes: e7cb072eb988 ("init/initramfs.c: do unpacking asynchronously") Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com> Reported-by: Bruno Goncalves <bgoncalv@redhat.com> Reported-by: Heiner Kallweit <hkallweit1@gmail.com> Cc: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nicholas Piggin [Wed, 8 Sep 2021 03:00:00 +0000 (20:00 -0700)]
fs/epoll: use a per-cpu counter for user's watches count
This counter tracks the number of watches a user has, to compare against
the 'max_user_watches' limit. This causes a scalability bottleneck on
SPECjbb2015 on large systems as there is only one user. Changing to a
per-cpu counter increases throughput of the benchmark by about 30% on a
16-socket, > 1000 thread system.
Joe Perches [Wed, 8 Sep 2021 02:59:57 +0000 (19:59 -0700)]
checkpatch: improve GIT_COMMIT_ID test
The preferred git commit id reference has the form
commit <SHA-1> ("Title line")
where SHA-1 is the commit hex hash with a minimum lenth of 12 and ("Title
line") is the complete title line of the commit with a (" prefix and ")
suffix.
The current tests fail when the "Title line" has one or more embedded
double quotes.
Improve the test that finds the commit SHA-1 hex hash then ("Title line")
by using $balanced_parens for a maximum of 3 consecutive lines.
[akpm@linux-foundation.org: add missing &&]
Link: https://lkml.kernel.org/r/976c6cdd680db4b55ae31b5fc2d1779da5c0dc66.camel@perches.com Signed-off-by: Joe Perches <joe@perches.com> Cc: Dwaipayan Ray <dwaipayanray1@gmail.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Denis Efremov <efremov@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
checkpatch: make email address check case insensitive
Instead of checkpatch requiring the patch author to exactly match the
signed-off-by tag, commit 48ca2d8ac8a1 ("checkpatch: add new warnings to
author signoff checks.") safely relaxed this requirement.
Although the local-part of an email address (local-part@domain), may be
case sensitive, exploiting the case sensitivity of mailbox local-parts
impedes interoperability and is discouraged. Mailbox domains follow
normal DNS rules and are hence not case sensitive. (Refer to
https://datatracker.ietf.org/doc/html/rfc5321#section-2.4.)
Further relax the patch author and signed-off-by tag comparison by making
the email address check case insensitive.
Link: https://lkml.kernel.org/r/20210816112725.173206-1-zohar@linux.ibm.com Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> Acked-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Randy Dunlap [Wed, 8 Sep 2021 02:58:54 +0000 (19:58 -0700)]
lib/iov_iter.c: fix kernel-doc warnings
Fix all kernel-doc warnings in lib/iov_iter.c:
lib/iov_iter.c:695: warning: Function parameter or member 'i' not described in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: Excess function parameter 'iter' description in '_copy_mc_to_iter'
lib/iov_iter.c:695: warning: No description found for return value of '_copy_mc_to_iter'
lib/iov_iter.c:758: warning: Function parameter or member 'i' not described in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: Excess function parameter 'iter' description in '_copy_from_iter_flushcache'
lib/iov_iter.c:758: warning: No description found for return value of '_copy_from_iter_flushcache'
Link: https://lkml.kernel.org/r/20210809051053.6531-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Randy Dunlap [Wed, 8 Sep 2021 02:58:51 +0000 (19:58 -0700)]
lib/dump_stack: correct kernel-doc notation
Fix kernel-doc warnings in dump_stack.c:
lib/dump_stack.c:97: warning: Function parameter or member 'log_lvl' not described in 'dump_stack_lvl'
lib/dump_stack.c:97: warning: expecting prototype for dump_stack(). Prototype was for dump_stack_lvl() instead
Link: https://lkml.kernel.org/r/20210809051643.17567-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
math: RATIONAL_KUNIT_TEST should depend on RATIONAL instead of selecting it
RATIONAL_KUNIT_TEST selects RATIONAL, thus enabling an optional feature
the user may not want to have enabled. Fix this by making the test depend
on RATIONAL instead.
Link: https://lkml.kernel.org/r/20210706100945.3803694-3-geert@linux-m68k.org Fixes: b6c75c4afceb8bc0 ("lib/math/rational: add Kunit test cases") Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Trent Piepho <tpiepho@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "math: RATIONAL and RATIONAL_KUNIT_TEST improvements".
This series makes the RATIONAL symbol tristate, so it is not forced
builtin if all users are modular, and makes the RATIONAL_KUNIT_TEST depend
on RATIONAL, to avoid enabling RATIONAL if there are no real users.
This patch (of 2):
All but one symbols that select RATIONAL are tristate, but RATIONAL itself
is bool. Change it to tristate, so the rational fractions support code
can be modular if no builtin code relies on it.
This should have been done with commit 91ed3ed0f798 ("MAINTAINERS: update
ClangBuiltLinux IRC chat") but I did not realize it was in two separate
spots.
Link: https://lkml.kernel.org/r/20210825211823.6406-3-nathan@kernel.org Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Sami Tolvanen <samitolvanen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pavel Skripkin [Wed, 8 Sep 2021 02:58:21 +0000 (19:58 -0700)]
profiling: fix shift-out-of-bounds bugs
Syzbot reported shift-out-of-bounds bug in profile_init().
The problem was in incorrect prof_shift. Since prof_shift value comes from
userspace we need to clamp this value into [0, BITS_PER_LONG -1]
boundaries.
Second possible shiht-out-of-bounds was found by Tetsuo:
sample_step local variable in read_profile() had "unsigned int" type,
but prof_shift allows to make a BITS_PER_LONG shift. So, to prevent
possible shiht-out-of-bounds sample_step type was changed to
"unsigned long".
Also, "unsigned short int" will be sufficient for storing
[0, BITS_PER_LONG] value, that's why there is no need for
"unsigned long" prof_shift.
Link: https://lkml.kernel.org/r/20210813140022.5011-1-paskripkin@gmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-and-tested-by: syzbot+e68c89a9510c159d9684@syzkaller.appspotmail.com Suggested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yang Yang [Wed, 8 Sep 2021 02:58:18 +0000 (19:58 -0700)]
kernel/acct.c: use dedicated helper to access rlimit values
Use rlimit() helper instead of manually writing whole chain from
task to rlimit value. See patch "posix-cpu-timers: Use dedicated
helper to access rlimit values".
Link: https://lkml.kernel.org/r/20210728030822.524789-1-yang.yang29@zte.com.cn Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Reported-by: Zeal Robot <zealci@zte.com.cn> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: sh_def@163.com <sh_def@163.com> Cc: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Daniel Lezcano [Wed, 8 Sep 2021 02:57:44 +0000 (19:57 -0700)]
units: change from 'L' to 'UL'
Patch series "Add Hz macros", v3.
There are multiple definitions of the HZ_PER_MHZ or HZ_PER_KHZ in the
different drivers. Instead of duplicating this definition again and
again, add one in the units.h header to be reused in all the place the
redefiniton occurs.
At the same time, change the type of the Watts, as they can not be
negative.
This patch (of 10):
The users of the macros are safe to be assigned with an unsigned instead
of signed as the variables using them are themselves unsigned.
Link: https://lkml.kernel.org/r/20210816114732.1834145-1-daniel.lezcano@linaro.org Link: https://lkml.kernel.org/r/20210816114732.1834145-2-daniel.lezcano@linaro.org Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Jonathan Cameron <jic23@kernel.org> Cc: Christian Eggers <ceggers@arri.de> Cc: Lukasz Luba <lukasz.luba@arm.com> Cc: MyungJoo Ham <myungjoo.ham@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lars-Peter Clausen <lars@metafoo.de> Cc: Peter Meerwald <pmeerw@pmeerw.net> Cc: Zhang Rui <rui.zhang@intel.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Chanwoo Choi <cw00.choi@samsung.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
connector: send event on write to /proc/[pid]/comm
While comm change event via prctl has been reported to proc connector by
'commit f786ecba4158 ("connector: add comm change event report to proc
connector")', connector listeners were missing comm changes by explicit
writes on /proc/[pid]/comm.
Let explicit writes on /proc/[pid]/comm report to proc connector.
Link: https://lkml.kernel.org/r/20210701133458epcms1p68e9eb9bd0eee8903ba26679a37d9d960@epcms1p6 Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Randy Dunlap [Wed, 8 Sep 2021 02:57:24 +0000 (19:57 -0700)]
alpha: pci-sysfs: fix all kernel-doc warnings
Fix all kernel-doc warnings in arch/alpha/kernel/pci-sysfs.c:
arch/alpha/kernel/pci-sysfs.c:67: warning: No description found for return value of 'pci_mmap_resource'
arch/alpha/kernel/pci-sysfs.c:115: warning: Function parameter or member 'pdev' not described in 'pci_remove_resource_files'
arch/alpha/kernel/pci-sysfs.c:115: warning: Excess function parameter 'dev' description in 'pci_remove_resource_files'
arch/alpha/kernel/pci-sysfs.c:230: warning: Function parameter or member 'pdev' not described in 'pci_create_resource_files'
arch/alpha/kernel/pci-sysfs.c:230: warning: Excess function parameter 'dev' description in 'pci_create_resource_files'
arch/alpha/kernel/pci-sysfs.c:232: warning: No description found for return value of 'pci_create_resource_files'
arch/alpha/kernel/pci-sysfs.c:305: warning: Function parameter or member 'bus' not described in 'pci_adjust_legacy_attr'
arch/alpha/kernel/pci-sysfs.c:305: warning: Excess function parameter 'b' description in 'pci_adjust_legacy_attr'
Link: https://lkml.kernel.org/r/20210808185249.31442-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Randy Dunlap [Wed, 8 Sep 2021 02:57:21 +0000 (19:57 -0700)]
alpha: agp: make empty macros use do-while-0 style
Copy these macros from ia64/include/asm/agp.h to avoid the
"empty-body" in 'if' statment warning.
drivers/char/agp/generic.c: In function 'agp_generic_destroy_page':
../drivers/char/agp/generic.c:1265:42: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
1265 | unmap_page_from_agp(page);
Link: https://lkml.kernel.org/r/20210809030822.20658-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: David Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:57:01 +0000 (19:57 -0700)]
mm/damon/dbgfs: support multiple contexts
In some use cases, users would want to run multiple monitoring context.
For example, if a user wants a high precision monitoring and dedicating
multiple CPUs for the job is ok, because DAMON creates one monitoring
thread per one context, the user can split the monitoring target regions
into multiple small regions and create one context for each region. Or,
someone might want to simultaneously monitor different address spaces,
e.g., both virtual address space and physical address space.
The DAMON's API allows such usage, but 'damon-dbgfs' does not. Therefore,
only kernel space DAMON users can do multiple contexts monitoring.
This commit allows the user space DAMON users to use multiple contexts
monitoring by introducing two new 'damon-dbgfs' debugfs files,
'mk_context' and 'rm_context'. Users can create a new monitoring context
by writing the desired name of the new context to 'mk_context'. Then, a
new directory with the name and having the files for setting of the
context ('attrs', 'target_ids' and 'record') will be created under the
debugfs directory. Writing the name of the context to remove to
'rm_context' will remove the related context and directory.
Link: https://lkml.kernel.org/r/20210716081449.22187-10-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leonard Foerster <foersleo@amazon.de> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:53 +0000 (19:56 -0700)]
mm/damon: implement a debugfs-based user space interface
DAMON is designed to be used by kernel space code such as the memory
management subsystems, and therefore it provides only kernel space API.
That said, letting the user space control DAMON could provide some
benefits to them. For example, it will allow user space to analyze their
specific workloads and make their own special optimizations.
For such cases, this commit implements a simple DAMON application kernel
module, namely 'damon-dbgfs', which merely wraps the DAMON api and exports
those to the user space via the debugfs.
'damon-dbgfs' exports three files, ``attrs``, ``target_ids``, and
``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
----------
Users can read and write the ``sampling interval``, ``aggregation
interval``, ``regions update interval``, and min/max number of monitoring
target regions by reading from and writing to the ``attrs`` file. For
example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10,
1000 and check it again::
Some types of address spaces supports multiple monitoring target. For
example, the virtual memory address spaces monitoring can have multiple
processes as the monitoring targets. Users can set the targets by writing
relevant id values of the targets to, and get the ids of the current
targets by reading from the ``target_ids`` file. In case of the virtual
address spaces monitoring, the values should be pids of the monitoring
target processes. For example, below commands set processes having pids
42 and 4242 as the monitoring targets and check it again::
Note that setting the target ids doesn't start the monitoring.
Turning On/Off
--------------
Setting the files as described above doesn't incur effect unless you
explicitly start the monitoring. You can start, stop, and check the
current status of the monitoring by writing to and reading from the
``monitor_on`` file. Writing ``on`` to the file starts the monitoring of
the targets with the attributes. Writing ``off`` to the file stops those.
DAMON also stops if every targets are invalidated (in case of the virtual
memory monitoring, target processes are invalidated when terminated).
Below example commands turn on, off, and check the status of DAMON::
# cd <debugfs>/damon
# echo on > monitor_on
# echo off > monitor_on
# cat monitor_on
off
Please note that you cannot write to the above-mentioned debugfs files
while the monitoring is turned on. If you write to the files while DAMON
is running, an error code such as ``-EBUSY`` will be returned.
SeongJae Park [Wed, 8 Sep 2021 02:56:48 +0000 (19:56 -0700)]
mm/damon: add a tracepoint
This commit adds a tracepoint for DAMON. It traces the monitoring results
of each region for each aggregation interval. Using this, DAMON can
easily integrated with tracepoints supporting tools such as perf.
Link: https://lkml.kernel.org/r/20210716081449.22187-7-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:44 +0000 (19:56 -0700)]
mm/damon: implement primitives for the virtual memory address spaces
This commit introduces a reference implementation of the address space
specific low level primitives for the virtual address space, so that users
of DAMON can easily monitor the data accesses on virtual address spaces of
specific processes by simply configuring the implementation to be used by
DAMON.
The low level primitives for the fundamental access monitoring are defined
in two parts:
1. Identification of the monitoring target address range for the address
space.
2. Access check of specific address range in the target space.
The reference implementation for the virtual address space does the works
as below.
PTE Accessed-bit Based Access Check
-----------------------------------
The implementation uses PTE Accessed-bit for basic access checks. That
is, it clears the bit for the next sampling target page and checks whether
it is set again after one sampling period. This could disturb the reclaim
logic. DAMON uses ``PG_idle`` and ``PG_young`` page flags to solve the
conflict, as Idle page tracking does.
VMA-based Target Address Range Construction
-------------------------------------------
Only small parts in the super-huge virtual address space of the processes
are mapped to physical memory and accessed. Thus, tracking the unmapped
address regions is just wasteful. However, because DAMON can deal with
some level of noise using the adaptive regions adjustment mechanism,
tracking every mapping is not strictly required but could even incur a
high overhead in some cases. That said, too huge unmapped areas inside
the monitoring target should be removed to not take the time for the
adaptive mechanism.
For the reason, this implementation converts the complex mappings to three
distinct regions that cover every mapped area of the address space. Also,
the two gaps between the three regions are the two biggest unmapped areas
in the given address space. The two biggest unmapped areas would be the
gap between the heap and the uppermost mmap()-ed region, and the gap
between the lowermost mmap()-ed region and the stack in most of the cases.
Because these gaps are exceptionally huge in usual address spaces,
excluding these will be sufficient to make a reasonable trade-off. Below
shows this in detail::
<heap>
<BIG UNMAPPED REGION 1>
<uppermost mmap()-ed region>
(small mmap()-ed regions and munmap()-ed regions)
<lowermost mmap()-ed region>
<BIG UNMAPPED REGION 2>
<stack>
[akpm@linux-foundation.org: mm/damon/vaddr.c needs highmem.h for kunmap_atomic()]
[sjpark@amazon.de: remove unnecessary PAGE_EXTENSION setup] Link: https://lkml.kernel.org/r/20210806095153.6444-2-sj38.park@gmail.com
[sjpark@amazon.de: safely walk page table] Link: https://lkml.kernel.org/r/20210831161800.29419-1-sj38.park@gmail.com Link: https://lkml.kernel.org/r/20210716081449.22187-6-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:40 +0000 (19:56 -0700)]
mm/idle_page_tracking: make PG_idle reusable
PG_idle and PG_young allow the two PTE Accessed bit users, Idle Page
Tracking and the reclaim logic concurrently work while not interfering
with each other. That is, when they need to clear the Accessed bit, they
set PG_young to represent the previous state of the bit, respectively.
And when they need to read the bit, if the bit is cleared, they further
read the PG_young to know whether the other has cleared the bit meanwhile
or not.
For yet another user of the PTE Accessed bit, we could add another page
flag, or extend the mechanism to use the flags. For the DAMON usecase,
however, we don't need to do that just yet. IDLE_PAGE_TRACKING and DAMON
are mutually exclusive, so there's only ever going to be one user of the
current set of flags.
In this commit, we split out the CONFIG options to allow for the use of
PG_young and PG_idle outside of idle page tracking.
In the next commit, DAMON's reference implementation of the virtual memory
address space monitoring primitives will use it.
[sjpark@amazon.de: set PAGE_EXTENSION for non-64BIT] Link: https://lkml.kernel.org/r/20210806095153.6444-1-sj38.park@gmail.com
[akpm@linux-foundation.org: tweak Kconfig text]
[sjpark@amazon.de: hide PAGE_IDLE_FLAG from users] Link: https://lkml.kernel.org/r/20210813081238.34705-1-sj38.park@gmail.com Link: https://lkml.kernel.org/r/20210716081449.22187-5-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leonard Foerster <foersleo@amazon.de> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:36 +0000 (19:56 -0700)]
mm/damon: adaptively adjust regions
Even somehow the initial monitoring target regions are well constructed to
fulfill the assumption (pages in same region have similar access
frequencies), the data access pattern can be dynamically changed. This
will result in low monitoring quality. To keep the assumption as much as
possible, DAMON adaptively merges and splits each region based on their
access frequency.
For each ``aggregation interval``, it compares the access frequencies of
adjacent regions and merges those if the frequency difference is small.
Then, after it reports and clears the aggregated access frequency of each
region, it splits each region into two or three regions if the total
number of regions will not exceed the user-specified maximum number of
regions after the split.
In this way, DAMON provides its best-effort quality and minimal overhead
while keeping the upper-bound overhead that users set.
Link: https://lkml.kernel.org/r/20210716081449.22187-4-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:32 +0000 (19:56 -0700)]
mm/damon/core: implement region-based sampling
To avoid the unbounded increase of the overhead, DAMON groups adjacent
pages that are assumed to have the same access frequencies into a
region. As long as the assumption (pages in a region have the same
access frequencies) is kept, only one page in the region is required to
be checked. Thus, for each ``sampling interval``,
1. the 'prepare_access_checks' primitive picks one page in each region,
2. waits for one ``sampling interval``,
3. checks whether the page is accessed meanwhile, and
4. increases the access count of the region if so.
Therefore, the monitoring overhead is controllable by adjusting the
number of regions. DAMON allows both the underlying primitives and user
callbacks to adjust regions for the trade-off. In other words, this
commit makes DAMON to use not only time-based sampling but also
space-based sampling.
This scheme, however, cannot preserve the quality of the output if the
assumption is not guaranteed. Next commit will address this problem.
Link: https://lkml.kernel.org/r/20210716081449.22187-3-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Marco Elver <elver@google.com> Cc: Markus Boehme <markubo@amazon.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SeongJae Park [Wed, 8 Sep 2021 02:56:28 +0000 (19:56 -0700)]
mm: introduce Data Access MONitor (DAMON)
Patch series "Introduce Data Access MONitor (DAMON)", v34.
Introduction
============
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON called 'region based sampling' and 'adaptive
regions adjustment' (refer to 'mechanisms.rst' in the 11th patch of this
patchset for the detail) make it
- accurate (The monitored information is useful for DRAM level memory
management. It might not appropriate for Cache-level accuracy,
though.),
- light-weight (The monitoring overhead is low enough to be applied
online while making no impact on the performance of the target
workloads.), and
- scalable (the upper-bound of the instrumentation overhead is
controllable regardless of the size of target workloads.).
Using this framework, therefore, several memory management mechanisms such
as reclamation and THP can be optimized to aware real data access
patterns. Experimental access pattern aware memory management
optimization works that incurring high instrumentation overhead will be
able to have another try.
Though DAMON is for kernel subsystems, it can be easily exposed to the
user space by writing a DAMON-wrapper kernel subsystem. Then, user space
users who have some special workloads will be able to write personalized
tools or applications for deeper understanding and specialized
optimizations of their systems.
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
The userspace tool[1] is available, released under GPLv2, and actively
being maintained. I am also planning to implement another basic user
interface in perf[2]. Also, the basic test suite for DAMON is available
under GPLv2[3].
DAMON is a part of a project called Data Access-aware Operating System
(DAOS). As the name implies, I want to improve the performance and
efficiency of systems using fine-grained data access patterns. The
optimizations are for both kernel and user spaces. I will therefore
modify or create kernel subsystems, export some of those to user space and
implement user space library / tools. Below shows the layers and
components for the project.
Raw Interface: debugfs, (sysfs), (damonfs), tracepoints, (sys_damon), ...
vvvvvvvvvvvvvvvvvvvvvvv USER SPACE vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
Library: (libdamon), ...
Tools: DAMO, (perf), ...
---------------------------------------------------------------------------
The components in parentheses or marked as '...' are not implemented yet
but in the future plan. IOW, those are the TODO tasks of DAOS project.
For more detail, please refer to the plans:
https://lore.kernel.org/linux-mm/20201202082731.24828-1-sjpark@amazon.com/
Evaluations
===========
We evaluated DAMON's overhead, monitoring quality and usefulness using 24
realistic workloads on my QEMU/KVM based virtual machine running a kernel
that v24 DAMON patchset is applied.
DAMON is lightweight. It increases system memory usage by 0.39% and slows
target workloads down by 1.16%.
DAMON is accurate and useful for memory management optimizations. An
experimental DAMON-based operation scheme for THP, namely 'ethp', removes
76.15% of THP memory overheads while preserving 51.25% of THP speedup.
Another experimental DAMON-based 'proactive reclamation' implementation,
'prcl', reduces 93.38% of residential sets and 23.63% of system memory
footprint while incurring only 1.22% runtime overhead in the best case
(parsec3/freqmine).
NOTE that the experimental THP optimization and proactive reclamation are
not for production but only for proof of concepts.
Please refer to the official document[1] or "Documentation/admin-guide/mm:
Add a document for DAMON" patch in this patchset for detailed evaluation
setup and results.
In summary, DAMON has used on production systems and proved its usefulness.
DAMON as a profiler
-------------------
We analyzed characteristics of a large scale production systems of our
customers using DAMON. The systems utilize 70GB DRAM and 36 CPUs. From
this, we were able to find interesting things below.
There were obviously different access pattern under idle workload and
active workload. Under the idle workload, it accessed large memory
regions with low frequency, while the active workload accessed small
memory regions with high freuqnecy.
DAMON found a 7GB memory region that showing obviously high access
frequency under the active workload. We believe this is the
performance-effective working set and need to be protected.
There was a 4KB memory region that showing highest access frequency under
not only active but also idle workloads. We think this must be a hottest
code section like thing that should never be paged out.
For this analysis, DAMON used only 0.3-1% of single CPU time. Because we
used recording-based analysis, it consumed about 3-12 MB of disk space per
20 minutes. This is only small amount of disk space, but we can further
reduce the disk usage by using non-recording-based DAMON features. I'd
like to argue that only DAMON can do such detailed analysis (finding 4KB
highest region in 70GB memory) with the light overhead.
DAMON as a system optimization tool
-----------------------------------
We also found below potential performance problems on the systems and made
DAMON-based solutions.
The system doesn't want to make the workload suffer from the page
reclamation and thus it utilizes enough DRAM but no swap device. However,
we found the system is actively reclaiming file-backed pages, because the
system has intensive file IO. The file IO turned out to be not
performance critical for the workload, but the customer wanted to ensure
performance critical file-backed pages like code section to not mistakenly
be evicted.
Using direct IO should or `mlock()` would be a straightforward solution,
but modifying the user space code is not easy for the customer.
Alternatively, we could use DAMON-based operation scheme[1]. By using it,
we can ask DAMON to track access frequency of each region and make
'process_madvise(MADV_WILLNEED)[2]' call for regions having specific size
and access frequency for a time interval.
We also found the system is having high number of TLB misses. We tried
'always' THP enabled policy and it greatly reduced TLB misses, but the
page reclamation also been more frequent due to the THP internal
fragmentation caused memory bloat. We could try another DAMON-based
operation scheme that applies 'MADV_HUGEPAGE' to memory regions having
>=2MB size and high access frequency, while applying 'MADV_NOHUGEPAGE' to
regions having <2MB size and low access frequency.
We do not own the systems so we only reported the analysis results and
possible optimization solutions to the customers. The customers satisfied
about the analysis results and promised to try the optimization guides.
Comparison with Idle Page Tracking
==================================
Idle Page Tracking allows users to set and read idleness of pages using a
bitmap file which represents each page with each bit of the file. One
recommended usage of it is working set size detection. Users can do that
by
1. find PFN of each page for workloads in interest,
2. set all the pages as idle by doing writes to the bitmap file,
3. wait until the workload accesses its working set, and
4. read the idleness of the pages again and count pages became not idle.
NOTE: While Idle Page Tracking is for user space users, DAMON is primarily
designed for kernel subsystems though it can easily exposed to the user
space. Hence, this section only assumes such user space use of DAMON.
For what use cases Idle Page Tracking would be better?
------------------------------------------------------
1. Flexible usecases other than hotness monitoring.
Because Idle Page Tracking allows users to control the primitive (Page
idleness) by themselves, Idle Page Tracking users can do anything they
want. Meanwhile, DAMON is primarily designed to monitor the hotness of
each memory region. For this, DAMON asks users to provide sampling
interval and aggregation interval. For the reason, there could be some
use case that using Idle Page Tracking is simpler.
2. Physical memory monitoring.
Idle Page Tracking receives PFN range as input, so natively supports
physical memory monitoring.
DAMON is designed to be extensible for multiple address spaces and use
cases by implementing and using primitives for the given use case.
Therefore, by theory, DAMON has no limitation in the type of target
address space as long as primitives for the given address space exists.
However, the default primitives introduced by this patchset supports only
virtual address spaces.
Therefore, for physical memory monitoring, you should implement your own
primitives and use it, or simply use Idle Page Tracking.
Nonetheless, RFC patchsets[1] for the physical memory address space
primitives is already available. It also supports user memory same to
Idle Page Tracking.
For what use cases DAMON is better?
-----------------------------------
1. Hotness Monitoring.
Idle Page Tracking let users know only if a page frame is accessed or not.
For hotness check, the user should write more code and use more memory.
DAMON do that by itself.
2. Low Monitoring Overhead
DAMON receives user's monitoring request with one step and then provide
the results. So, roughly speaking, DAMON require only O(1) user/kernel
context switches.
In case of Idle Page Tracking, however, because the interface receives
contiguous page frames, the number of user/kernel context switches
increases as the monitoring target becomes complex and huge. As a result,
the context switch overhead could be not negligible.
Moreover, DAMON is born to handle with the monitoring overhead. Because
the core mechanism is pure logical, Idle Page Tracking users might be able
to implement the mechanism on their own, but it would be time consuming
and the user/kernel context switching will still more frequent than that
of DAMON. Also, the kernel subsystems cannot use the logic in this case.
3. Page granularity working set size detection.
Until v22 of this patchset, this was categorized as the thing Idle Page
Tracking could do better, because DAMON basically maintains additional
metadata for each of the monitoring target regions. So, in the page
granularity working set size detection use case, DAMON would incur (number
of monitoring target pages * size of metadata) memory overhead. Size of
the single metadata item is about 54 bytes, so assuming 4KB pages, about
1.3% of monitoring target pages will be additionally used.
All essential metadata for Idle Page Tracking are embedded in 'struct
page' and page table entries. Therefore, in this use case, only one
counter variable for working set size accounting is required if Idle Page
Tracking is used.
There are more details to consider, but roughly speaking, this is true in
most cases.
However, the situation changed from v23. Now DAMON supports arbitrary
types of monitoring targets, which don't use the metadata. Using that,
DAMON can do the working set size detection with no additional space
overhead but less user-kernel context switch. A first draft for the
implementation of monitoring primitives for this usage is available in a
DAMON development tree[1]. An RFC patchset for it based on this patchset
will also be available soon.
Since v24, the arbitrary type support is dropped from this patchset
because this patchset doesn't introduce real use of the type. You can
still get it from the DAMON development tree[2], though.
While Idle Page Tracking has tight coupling with base primitives (PG_Idle
and page table Accessed bits), DAMON is designed to be extensible for many
use cases and address spaces. If you need some special address type or
want to use special h/w access check primitives, you can write your own
primitives for that and configure DAMON to use those. Therefore, if your
use case could be changed a lot in future, using DAMON could be better.
Can I use both Idle Page Tracking and DAMON?
--------------------------------------------
Yes, though using them concurrently for overlapping memory regions could
result in interference to each other. Nevertheless, such use case would
be rare or makes no sense at all. Even in the case, the noise would bot
be really significant. So, you can choose whatever you want depending on
the characteristics of your use cases.
More Information
================
We prepared a showcase web site[1] that you can get more information.
There are
- the official documentations[2],
- the heatmap format dynamic access pattern of various realistic workloads for
heap area[3], mmap()-ed area[4], and stack[5] area,
- the dynamic working set size distribution[6] and chronological working set
size changes[7], and
- the latest performance test results[8].
Baseline and Complete Git Trees
===============================
The patches are based on the latest -mm tree, specifically
v5.14-rc1-mmots-2021-07-15-18-47 of https://github.com/hnaz/linux-mm. You can
also clone the complete git tree:
The web is also available:
https://github.com/sjp38/linux/releases/tag/damon/patches/v34
Development Trees
-----------------
There are a couple of trees for entire DAMON patchset series and features
for future release.
- For latest release: https://github.com/sjp38/linux/tree/damon/master
- For next release: https://github.com/sjp38/linux/tree/damon/next
Long-term Support Trees
-----------------------
For people who want to test DAMON but using LTS kernels, there are another
couple of trees based on two latest LTS kernels respectively and
containing the 'damon/master' backports.
- For v5.4.y: https://github.com/sjp38/linux/tree/damon/for-v5.4.y
- For v5.10.y: https://github.com/sjp38/linux/tree/damon/for-v5.10.y
Amazon Linux Kernel Trees
-------------------------
DAMON is also merged in two public Amazon Linux kernel trees that based on
v5.4.y[1] and v5.10.y[2].
Git Tree for Diff of Patches
============================
For easy review of diff between different versions of each patch, I
prepared a git tree containing all versions of the DAMON patchset series:
https://github.com/sjp38/damon-patches
You can clone it and use 'diff' for easy review of changes between
different versions of the patchset. For example:
First three patches implement the core logics of DAMON. The 1st patch
introduces basic sampling based hotness monitoring for arbitrary types of
targets. Following two patches implement the core mechanisms for control
of overhead and accuracy, namely regions based sampling (patch 2) and
adaptive regions adjustment (patch 3).
Now the essential parts of DAMON is complete, but it cannot work unless
someone provides monitoring primitives for a specific use case. The
following two patches make it just work for virtual address spaces
monitoring. The 4th patch makes 'PG_idle' can be used by DAMON and the
5th patch implements the virtual memory address space specific monitoring
primitives using page table Accessed bits and the 'PG_idle' page flag.
Now DAMON just works for virtual address space monitoring via the kernel
space api. To let the user space users can use DAMON, following four
patches add interfaces for them. The 6th patch adds a tracepoint for
monitoring results. The 7th patch implements a DAMON application kernel
module, namely damon-dbgfs, that simply wraps DAMON and exposes DAMON
interface to the user space via the debugfs interface. The 8th patch
further exports pid of monitoring thread (kdamond) to user space for
easier cpu usage accounting, and the 9th patch makes the debugfs interface
to support multiple contexts.
Three patches for maintainability follows. The 10th patch adds
documentations for both the user space and the kernel space. The 11th
patch provides unit tests (based on the kunit) while the 12th patch adds
user space tests (based on the kselftest).
Finally, the last patch (13th) updates the MAINTAINERS file.
This patch (of 13):
DAMON is a data access monitoring framework for the Linux kernel. The
core mechanisms of DAMON make it
- accurate (the monitoring output is useful enough for DRAM level
performance-centric memory management; It might be inappropriate for
CPU cache levels, though),
- light-weight (the monitoring overhead is normally low enough to be
applied online), and
- scalable (the upper-bound of the overhead is in constant range
regardless of the size of target workloads).
Using this framework, hence, we can easily write efficient kernel space
data access monitoring applications. For example, the kernel's memory
management mechanisms can make advanced decisions using this.
Experimental data access aware optimization works that incurring high
access monitoring overhead could again be implemented on top of this.
Due to its simple and flexible interface, providing user space interface
would be also easy. Then, user space users who have some special
workloads can write personalized applications for better understanding and
optimizations of their workloads and systems.
===
Nevertheless, this commit is defining and implementing only basic access
check part without the overhead-accuracy handling core logic. The basic
access check is as below.
The output of DAMON says what memory regions are how frequently accessed
for a given duration. The resolution of the access frequency is
controlled by setting ``sampling interval`` and ``aggregation interval``.
In detail, DAMON checks access to each page per ``sampling interval`` and
aggregates the results. In other words, counts the number of the accesses
to each region. After each ``aggregation interval`` passes, DAMON calls
callback functions that previously registered by users so that users can
read the aggregated results and then clears the results. This can be
described in below simple pseudo-code::
init()
while monitoring_on:
for page in monitoring_target:
if accessed(page):
nr_accesses[page] += 1
if time() % aggregation_interval == 0:
for callback in user_registered_callbacks:
callback(monitoring_target, nr_accesses)
for page in monitoring_target:
nr_accesses[page] = 0
if time() % update_interval == 0:
update()
sleep(sampling interval)
The target regions constructed at the beginning of the monitoring and
updated after each ``regions_update_interval``, because the target regions
could be dynamically changed (e.g., mmap() or memory hotplug). The
monitoring overhead of this mechanism will arbitrarily increase as the
size of the target workload grows.
The basic monitoring primitives for actual access check and dynamic target
regions construction aren't in the core part of DAMON. Instead, it allows
users to implement their own primitives that are optimized for their use
case and configure DAMON to use those. In other words, users cannot use
current version of DAMON without some additional works.
Following commits will implement the core mechanisms for the
overhead-accuracy control and default primitives implementations.
Link: https://lkml.kernel.org/r/20210716081449.22187-1-sj38.park@gmail.com Link: https://lkml.kernel.org/r/20210716081449.22187-2-sj38.park@gmail.com Signed-off-by: SeongJae Park <sjpark@amazon.de> Reviewed-by: Leonard Foerster <foersleo@amazon.de> Reviewed-by: Fernand Sieber <sieberf@amazon.com> Acked-by: Shakeel Butt <shakeelb@google.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Amit Shah <amit@kernel.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: David Hildenbrand <david@redhat.com> Cc: David Woodhouse <dwmw@amazon.com> Cc: Marco Elver <elver@google.com> Cc: Fan Du <fan.du@intel.com> Cc: Greg Kroah-Hartman <greg@kroah.com> Cc: Greg Thelen <gthelen@google.com> Cc: Joe Perches <joe@perches.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Maximilian Heyne <mheyne@amazon.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: David Rientjes <rientjes@google.com> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Brendan Higgins <brendanhiggins@google.com> Cc: Markus Boehme <markubo@amazon.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Marco Elver [Wed, 8 Sep 2021 02:56:24 +0000 (19:56 -0700)]
kfence: test: fail fast if disabled at boot
Fail kfence_test fast if KFENCE was disabled at boot, instead of each test
case trying several seconds to allocate from KFENCE and failing. KUnit
will fail all test cases if kunit_suite::init returns an error.
Even if KFENCE was disabled, we still want the test to fail, so that CI
systems that parse KUnit output will alert on KFENCE being disabled
(accidentally or otherwise).
Link: https://lkml.kernel.org/r/20210825105533.1247922-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Acked-by: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Marco Elver [Wed, 8 Sep 2021 02:56:21 +0000 (19:56 -0700)]
kfence: show cpu and timestamp in alloc/free info
Record cpu and timestamp on allocations and frees, and show them in
reports. Upon an error, this can help correlate earlier messages in the
kernel log via allocation and free timestamps.
Link: https://lkml.kernel.org/r/20210714175312.2947941-1-elver@google.com Suggested-by: Joern Engel <joern@purestorage.com> Signed-off-by: Marco Elver <elver@google.com> Acked-by: Alexander Potapenko <glider@google.com> Acked-by: Joern Engel <joern@purestorage.com> Cc: Yuanyuan Zhong <yzhong@purestorage.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a secret memory region is active, memfd_secret disables hibernation.
One of the goals is to keep the secret data from being written to
persistent-storage.
It accomplishes this by maintaining a reference count to
`secretmem_users`. Once this reference is held your system can not be
hibernated due to the check in `hibernation_available()`. However,
because `secretmem_users` is of type `atomic_t`, reference counter
overflows are possible.
As you can see there's an `atomic_inc` for each `memfd` that is opened in
the `memfd_secret` syscall. If a local attacker succeeds to open 2^32
memfd's, the counter will wrap around to 0. This implies that you may
hibernate again, even though there are still regions of this secret
memory, thereby bypassing the security check.
In an attempt to fix this I have used `refcount_t` instead of `atomic_t`
which prevents reference counter overflows.
Link: https://lkml.kernel.org/r/20210820043339.2151352-1-jordy@pwning.systems Signed-off-by: Jordy Zomer <jordy@pwning.systems> Cc: Kees Cook <keescook@chromium.org>, Cc: Jordy Zomer <jordy@jordyzomer.github.io> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Mike Rapoport <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
highmem: don't disable preemption on RT in kmap_atomic()
kmap_atomic() disables preemption and pagefaults for historical reasons.
The conversion to kmap_local(), which only disables migration, cannot be
done wholesale because quite some call sites need to be updated to
accommodate with the changed semantics.
On PREEMPT_RT enabled kernels the kmap_atomic() semantics are problematic
due to the implicit disabling of preemption which makes it impossible to
acquire 'sleeping' spinlocks within the kmap atomic sections.
PREEMPT_RT replaces the preempt_disable() with a migrate_disable() for
more than a decade. It could be argued that this is a justification to do
this unconditionally, but PREEMPT_RT covers only a limited number of
architectures and it disables some functionality which limits the coverage
further.
Limit the replacement to PREEMPT_RT for now.
Link: https://lkml.kernel.org/r/20210810091116.pocdmaatdcogvdso@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
early_ioremap_reset() reserved a weak function so that architectures can
provide a specific cleanup. Now no architectures use it, remove this
redundant function.
The first patch moves a little code around the vmalloc/ioremap boundary
following a bigger move by Nick earlier. The second enforces
non-executable mapping on ioremap just like we do for vmap. No driver
currently uses executable mappings anyway, as they should.
This patch (of 2):
This keeps it together with the implementation, and to remove the
vmap_range wrapper.
Muchun Song [Wed, 8 Sep 2021 02:55:55 +0000 (19:55 -0700)]
mm: remove redundant compound_head() calling
There is a READ_ONCE() in the macro of compound_head(), which will prevent
compiler from optimizing the code when there are more than once calling of
it in a function. Remove the redundant calling of compound_head() from
page_to_index() and page_add_file_rmap() for better code generation.
Link: https://lkml.kernel.org/r/20210811101431.83940-1-songmuchun@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: David Howells <dhowells@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: William Kucharski <william.kucharski@oracle.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miaohe Lin [Wed, 8 Sep 2021 02:55:52 +0000 (19:55 -0700)]
mm/memory_hotplug: use helper zone_is_zone_device() to simplify the code
Patch series "Cleanup and fixups for memory hotplug".
This series contains cleanup to use helper function to simplify the code.
Also we fix some potential bugs. More details can be found in the
respective changelogs.
This patch (of 3):
Use helper zone_is_zone_device() to simplify the code and remove some
explicit CONFIG_ZONE_DEVICE codes.
Link: https://lkml.kernel.org/r/20210821094246.10149-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20210821094246.10149-2-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Chris Goldsworthy <cgoldswo@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory_hotplug: improved dynamic memory group aware "auto-movable" online policy
Currently, the "auto-movable" online policy does not allow for hotplugged
KERNEL (ZONE_NORMAL) memory to increase the amount of MOVABLE memory we
can have, primarily, because there is no coordiantion across memory
devices and we don't want to create zone-imbalances accidentially when
unplugging memory.
However, within a single memory device it's different. Let's allow for
KERNEL memory within a dynamic memory group to allow for more MOVABLE
within the same memory group. The only thing we have to take care of is
that the managing driver avoids zone imbalances by unplugging MOVABLE
memory first, otherwise there can be corner cases where unplug of memory
could result in (accidential) zone imbalances.
virtio-mem is the only user of dynamic memory groups and recently added
support for prioritizing unplug of ZONE_MOVABLE over ZONE_NORMAL, so we
don't need a new toggle to enable it for dynamic memory groups.
We limit this handling to dynamic memory groups, because:
* We want to keep the runtime overhead for collecting stats when
onlining a single memory block small. We tend to have only a handful of
dynamic memory groups, but we can have quite some static memory groups
(e.g., 256 DIMMs).
* It doesn't make too much sense for static memory groups, as we try
onlining all applicable memory blocks either completely to ZONE_MOVABLE
or not. In ordinary operation, we won't have a mixture of zones within
a static memory group.
When adding memory to a dynamic memory group, we'll first online memory to
ZONE_MOVABLE as long as early KERNEL memory allows for it. Then, we'll
online the next unit(s) to ZONE_NORMAL, until we can online the next
unit(s) to ZONE_MOVABLE.
For a simple virtio-mem device with a MOVABLE:KERNEL ratio of 3:1, it will
result in a layout like:
[M][M][M][M][M][M][M][M][N][M][M][M][N][M][M][M]...
^ movable memory due to early kernel memory
^ allows for more movable memory ...
^-----^ ... here
^ allows for more movable memory ...
^-----^ ... here
While the created layout is sub-optimal when it comes to contiguous zones,
it gives us the maximum flexibility when dynamically growing/shrinking a
device; we can grow small VMs really big in small steps, and still shrink
reliably to e.g., 1/4 of the maximum VM size in this example, removing
full memory blocks along with meta data more reliably.
Mark dynamic memory groups in the xarray such that we can efficiently
iterate over them when collecting stats. In usual setups, we have one
virtio-mem device per NUMA node, and usually only a small number of NUMA
nodes.
Note: for now, there seems to be no compelling reason to make this
behavior configurable.
Link: https://lkml.kernel.org/r/20210806124715.17090-10-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory_hotplug: memory group aware "auto-movable" online policy
Use memory groups to improve our "auto-movable" onlining policy:
1. For static memory groups (e.g., a DIMM), online a memory block MOVABLE
only if all other memory blocks in the group are either MOVABLE or could
be onlined MOVABLE. A DIMM will either be MOVABLE or not, not a mixture.
2. For dynamic memory groups (e.g., a virtio-mem device), online a
memory block MOVABLE only if all other memory blocks inside the
current unit are either MOVABLE or could be onlined MOVABLE. For a
virtio-mem device with a device block size with 512 MiB, all 128 MiB
memory blocks wihin a 512 MiB unit will either be MOVABLE or not, not
a mixture.
We have to pass the memory group to zone_for_pfn_range() to take the
memory group into account.
Note: for now, there seems to be no compelling reason to make this
behavior configurable.
Link: https://lkml.kernel.org/r/20210806124715.17090-9-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
virtio-mem: use a single dynamic memory group for a single virtio-mem device
Let's use a single dynamic memory group.
Link: https://lkml.kernel.org/r/20210806124715.17090-8-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dax/kmem: use a single static memory group for a single probed unit
Although dax/kmem users often disable auto-onlining and instead online
memory manually (usually to ZONE_MOVABLE), there is still value in having
auto-onlining be aware of the relationship of memory blocks.
Let's treat one probed unit as a single static memory device, similar to a
single ACPI memory device.
Link: https://lkml.kernel.org/r/20210806124715.17090-7-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ACPI: memhotplug: use a single static memory group for a single memory device
Let's group all memory we add for a single memory device - we want a
single node for that (which also seems to be the sane thing to do).
We won't care for now about memory that was already added to the system
(e.g., via e820) -- usually *all* memory of a memory device was already
added and we'll fail acpi_memory_enable_device().
Link: https://lkml.kernel.org/r/20210806124715.17090-6-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory_hotplug: track present pages in memory groups
Let's track all present pages in each memory group. Especially, track
memory present in ZONE_MOVABLE and memory present in one of the kernel
zones (which really only is ZONE_NORMAL right now as memory groups only
apply to hotplugged memory) separately within a memory group, to prepare
for making smart auto-online decision for individual memory blocks within
a memory group based on group statistics.
Link: https://lkml.kernel.org/r/20210806124715.17090-5-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/base/memory: introduce "memory groups" to logically group memory blocks
In our "auto-movable" memory onlining policy, we want to make decisions
across memory blocks of a single memory device. Examples of memory
devices include ACPI memory devices (in the simplest case a single DIMM)
and virtio-mem. For now, we don't have a connection between a single
memory block device and the real memory device. Each memory device
consists of 1..X memory block devices.
Let's logically group memory blocks belonging to the same memory device in
"memory groups". Memory groups can span multiple physical ranges and a
memory group itself does not contain any information regarding physical
ranges, only properties (e.g., "max_pages") necessary for improved memory
onlining.
Introduce two memory group types:
1) Static memory group: E.g., a single ACPI memory device, consisting
of 1..X memory resources. A memory group consists of 1..Y memory
blocks. The whole group is added/removed in one go. If any part
cannot get offlined, the whole group cannot be removed.
2) Dynamic memory group: E.g., a single virtio-mem device. Memory is
dynamically added/removed in a fixed granularity, called a "unit",
consisting of 1..X memory blocks. A unit is added/removed in one go.
If any part of a unit cannot get offlined, the whole unit cannot be
removed.
In case of 1) we usually want either all memory managed by ZONE_MOVABLE or
none. In case of 2) we usually want to have as many units as possible
managed by ZONE_MOVABLE. We want a single unit to be of the same type.
For now, memory groups are an internal concept that is not exposed to user
space; we might want to change that in the future, though.
add_memory() users can specify a mgid instead of a nid when passing the
MHP_NID_IS_MGID flag.
Link: https://lkml.kernel.org/r/20210806124715.17090-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When onlining without specifying a zone (using "online" instead of
"online_kernel" or "online_movable"), we currently select a zone such that
existing zones are kept contiguous. This online policy made sense in the
past, where contiguous zones where required.
We'd like to implement smarter policies, however:
* User space has little insight. As one example, it has no idea which
memory blocks logically belong together (e.g., to a DIMM or to a
virtio-mem device).
* Drivers that add memory in separate memory blocks, especially
virtio-mem, want memory to get onlined right from the kernel when
adding.
So we really want to have onlining to differing zones managed in the
kernel, configured by user space.
We see more and more cases where we might eventually hotplug a lot of
memory in the future (e.g., eventually grow a 2 GiB VM to 64 GiB),
however:
* Resizing happens dynamically, in smaller steps in both directions
(e.g., 2 GiB -> 8 GiB -> 4 GiB -> 16 GiB ...)
* We still want as much flexibility as possible, especially,
hotunplugging as much memory as possible later.
We can really only use "online_movable" if we know that the amount of
memory we are going to hotplug upfront, and we know that it won't result
in a zone imbalance. So in our example, a 2 GiB VM that could grow to 64
GiB could currently not use "online_movable", and instead, "online_kernel"
would have to be used, resulting in worse (no) memory hotunplug
reliability.
Let's add a new "auto-movable" online policy that considers the current
zone ratios (global, per-node) to determine, whether we a memory block can
be onlined to ZONE_MOVABLE:
MOVABLE : KERNEL
However, internally we'll only consider the following ratio for now:
MOVABLE : KERNEL_EARLY
For now, we don't allow for hotplugged KERNEL memory to allow for more
MOVABLE memory, because there is no coordination across memory devices.
In follow-up patches, we will allow for more KERNEL memory within a memory
device to allow for more MOVABLE memory within the same memory device --
which only makes sense for special memory device types.
We base our calculation on "present pages", see the code comments for
details. Hotplugged memory will get online to ZONE_MOVABLE if the
configured ratio allows for it. Depending on the setup, this can result
in fragmented zones, which can make compaction slower and dynamic
allocation of gigantic pages when not using CMA less reliable (... which
is already pretty unreliable).
The old policy will be the default and called "contig-zones". In
follow-up patches, our new policy will use additional information, such as
memory groups, to make even smarter decisions across memory blocks.
Configuration:
* memory_hotplug.online_policy is used to switch between both polices
and defaults to "contig-zones".
* memory_hotplug.auto_movable_ratio defines the maximum ratio is in
percent and defaults to "301" -- allowing e.g., most 8 GiB machines to
grow to 32 GiB and have all hotplugged memory in ZONE_MOVABLE. The
additional percent accounts for a handful of lost present pages (e.g.,
firmware allocations). User space is expected to adjust this ratio when
enabling the new "auto-movable" policy, though.
* memory_hotplug.auto_movable_numa_aware considers numa node stats in
addition to global stats, and defaults to "true".
Note: just like the old policy, the new policy won't take things like
unmovable huge pages or memory ballooning that doesn't support balloon
compaction into account. User space has to configure onlining
accordingly.
Link: https://lkml.kernel.org/r/20210806124715.17090-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hui Zhu <teawater@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/memory_hotplug: "auto-movable" online policy and memory groups", v3.
I. Goal
The goal of this series is improving in-kernel auto-online support. It
tackles the fundamental problems that:
1) We can create zone imbalances when onlining all memory blindly to
ZONE_MOVABLE, in the worst case crashing the system. We have to know
upfront how much memory we are going to hotplug such that we can
safely enable auto-onlining of all hotplugged memory to ZONE_MOVABLE
via "online_movable". This is far from practical and only applicable in
limited setups -- like inside VMs under the RHV/oVirt hypervisor which
will never hotplug more than 3 times the boot memory (and the
limitation is only in place due to the Linux limitation).
2) We see more setups that implement dynamic VM resizing, hot(un)plugging
memory to resize VM memory. In these setups, we might hotplug a lot of
memory, but it might happen in various small steps in both directions
(e.g., 2 GiB -> 8 GiB -> 4 GiB -> 16 GiB ...). virtio-mem is the
primary driver of this upstream right now, performing such dynamic
resizing NUMA-aware via multiple virtio-mem devices.
Onlining all hotplugged memory to ZONE_NORMAL means we basically have
no hotunplug guarantees. Onlining all to ZONE_MOVABLE means we can
easily run into zone imbalances when growing a VM. We want a mixture,
and we want as much memory as reasonable/configured in ZONE_MOVABLE.
Details regarding zone imbalances can be found at [1].
3) Memory devices consist of 1..X memory block devices, however, the
kernel doesn't really track the relationship. Consequently, also user
space has no idea. We want to make per-device decisions.
As one example, for memory hotunplug it doesn't make sense to use a
mixture of zones within a single DIMM: we want all MOVABLE if
possible, otherwise all !MOVABLE, because any !MOVABLE part will easily
block the whole DIMM from getting hotunplugged.
As another example, virtio-mem operates on individual units that span
1..X memory blocks. Similar to a DIMM, we want a unit to either be all
MOVABLE or !MOVABLE. A "unit" can be thought of like a DIMM, however,
all units of a virtio-mem device logically belong together and are
managed (added/removed) by a single driver. We want as much memory of
a virtio-mem device to be MOVABLE as possible.
4) We want memory onlining to be done right from the kernel while adding
memory, not triggered by user space via udev rules; for example, this
is reqired for fast memory hotplug for drivers that add individual
memory blocks, like virito-mem. We want a way to configure a policy in
the kernel and avoid implementing advanced policies in user space.
The auto-onlining support we have in the kernel is not sufficient. All we
have is a) online everything MOVABLE (online_movable) b) online everything
!MOVABLE (online_kernel) c) keep zones contiguous (online). This series
allows configuring c) to mean instead "online movable if possible
according to the coniguration, driven by a maximum MOVABLE:KERNEL ratio"
-- a new onlining policy.
II. Approach
This series does 3 things:
1) Introduces the "auto-movable" online policy that initially operates on
individual memory blocks only. It uses a maximum MOVABLE:KERNEL ratio
to make a decision whether a memory block will be onlined to
ZONE_MOVABLE or not. However, in the basic form, hotplugged KERNEL
memory does not allow for more MOVABLE memory (details in the
patches). CMA memory is treated like MOVABLE memory.
2) Introduces static (e.g., DIMM) and dynamic (e.g., virtio-mem) memory
groups and uses group information to make decisions in the
"auto-movable" online policy across memory blocks of a single memory
device (modeled as memory group). More details can be found in patch
#3 or in the DIMM example below.
3) Maximizes ZONE_MOVABLE memory within dynamic memory groups, by
allowing ZONE_NORMAL memory within a dynamic memory group to allow for
more ZONE_MOVABLE memory within the same memory group. The target use
case is dynamic VM resizing using virtio-mem. See the virtio-mem
example below.
I remember that the basic idea of using a ratio to implement a policy in
the kernel was once mentioned by Vitaly Kuznetsov, but I might be wrong (I
lost the pointer to that discussion).
For me, the main use case is using it along with virtio-mem (and DIMMs /
ppc64 dlpar where necessary) for dynamic resizing of VMs, increasing the
amount of memory we can hotunplug reliably again if we might eventually
hotplug a lot of memory to a VM.
III. Target Usage
The target usage will be:
1) Linux boots with "mhp_default_online_type=offline"
2) User space (e.g., systemd unit) configures memory onlining (according
to a config file and system properties), for example:
* Setting memory_hotplug.online_policy=auto-movable
* Setting memory_hotplug.auto_movable_ratio=301
* Setting memory_hotplug.auto_movable_numa_aware=true
3) User space enabled auto onlining via "echo online >
/sys/devices/system/memory/auto_online_blocks"
4) User space triggers manual onlining of all already-offline memory
blocks (go over offline memory blocks and set them to "online")
IV. Example
For DIMMs, hotplugging 4 GiB DIMMs to a 4 GiB VM with a configured ratio of
301% results in the following layout:
Memory block 0-15: DMA32 (early)
Memory block 32-47: Normal (early)
Memory block 48-79: Movable (DIMM 0)
Memory block 80-111: Movable (DIMM 1)
Memory block 112-143: Movable (DIMM 2)
Memory block 144-275: Normal (DIMM 3)
Memory block 176-207: Normal (DIMM 4)
... all Normal
(-> hotplugged Normal memory does not allow for more Movable memory)
For virtio-mem, using a simple, single virtio-mem device with a 4 GiB VM
will result in the following layout:
Memory block 0-15: DMA32 (early)
Memory block 32-47: Normal (early)
Memory block 48-143: Movable (virtio-mem, first 12 GiB)
Memory block 144: Normal (virtio-mem, next 128 MiB)
Memory block 145-147: Movable (virtio-mem, next 384 MiB)
Memory block 148: Normal (virtio-mem, next 128 MiB)
Memory block 149-151: Movable (virtio-mem, next 384 MiB)
... Normal/Movable mixture as above
(-> hotplugged Normal memory allows for more Movable memory within
the same device)
Which gives us maximum flexibility when dynamically growing/shrinking a
VM in smaller steps.
V. Doc Update
I'll update the memory-hotplug.rst documentation, once the overhaul [1] is
usptream. Until then, details can be found in patch #2.
VI. Future Work
1) Use memory groups for ppc64 dlpar
2) Being able to specify a portion of (early) kernel memory that will be
excluded from the ratio. Like "128 MiB globally/per node" are excluded.
This might be helpful when starting VMs with extremely small memory
footprint (e.g., 128 MiB) and hotplugging memory later -- not wanting
the first hotplugged units getting onlined to ZONE_MOVABLE. One
alternative would be a trigger to not consider ZONE_DMA memory
in the ratio. We'll have to see if this is really rrequired.
3) Indicate to user space that MOVABLE might be a bad idea -- especially
relevant when memory ballooning without support for balloon compaction
is active.
This patch (of 9):
For implementing a new memory onlining policy, which determines when to
online memory blocks to ZONE_MOVABLE semi-automatically, we need the
number of present early (boot) pages -- present pages excluding hotplugged
pages. Let's track these pages per zone.
Pass a page instead of the zone to adjust_present_page_count(), similar as
adjust_managed_page_count() and derive the zone from the page.
It's worth noting that a memory block to be offlined/onlined is either
completely "early" or "not early". add_memory() and friends can only add
complete memory blocks and we only online/offline complete (individual)
memory blocks.
Link: https://lkml.kernel.org/r/20210806124715.17090-1-david@redhat.com Link: https://lkml.kernel.org/r/20210806124715.17090-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Marek Kedzierski <mkedzier@redhat.com> Cc: Hui Zhu <teawater@gmail.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mike Rapoport <rppt@kernel.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory_hotplug: remove nid parameter from remove_memory() and friends
There is only a single user remaining. We can simply lookup the nid only
used for node offlining purposes when walking our memory blocks. We don't
expect to remove multi-nid ranges; and if we'd ever do, we most probably
don't care about removing multi-nid ranges that actually result in empty
nodes.
If ever required, we can detect the "multi-nid" scenario and simply try
offlining all online nodes.
Link: https://lkml.kernel.org/r/20210712124052.26491-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Scott Cheloha <cheloha@linux.ibm.com> Cc: Anton Blanchard <anton@ozlabs.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Baoquan He <bhe@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jia He <justin.he@arm.com> Cc: Joe Perches <joe@perches.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michel Lespinasse <michel@lespinasse.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pankaj Gupta <pankaj.gupta@ionos.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pierre Morel <pmorel@linux.ibm.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Rich Felker <dalias@libc.org> Cc: Sergei Trofimovich <slyfox@gentoo.org> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Checkpatch complained on a follow-up patch that we are using "unsigned"
here, which defaults to "unsigned int" and checkpatch is correct.
As we will search for a fitting zone using the wrong pfn, we might end
up onlining memory to one of the special kernel zones, such as ZONE_DMA,
which can end badly as the onlined memory does not satisfy properties of
these zones.
Use "unsigned long" instead, just as we do in other places when handling
PFNs. This can bite us once we have physical addresses in the range of
multiple TB.
Link: https://lkml.kernel.org/r/20210712124052.26491-2-david@redhat.com Fixes: e5e689302633 ("mm, memory_hotplug: display allowed zones in the preferred ordering") Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: David Hildenbrand <david@redhat.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mike Rapoport <rppt@kernel.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: virtualization@lists.linux-foundation.org Cc: Andy Lutomirski <luto@kernel.org> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: Anton Blanchard <anton@ozlabs.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Baoquan He <bhe@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Dave Jiang <dave.jiang@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jia He <justin.he@arm.com> Cc: Joe Perches <joe@perches.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Michel Lespinasse <michel@lespinasse.org> Cc: Nathan Lynch <nathanl@linux.ibm.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pierre Morel <pmorel@linux.ibm.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Rich Felker <dalias@libc.org> Cc: Scott Cheloha <cheloha@linux.ibm.com> Cc: Sergei Trofimovich <slyfox@gentoo.org> Cc: Thiago Jung Bauermann <bauerman@linux.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mike Rapoport [Wed, 8 Sep 2021 02:54:52 +0000 (19:54 -0700)]
mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE
Patch series "mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE".
After recent updates to freeing unused parts of the memory map, no
architecture can have holes in the memory map within a pageblock. This
makes pfn_valid_within() check and CONFIG_HOLES_IN_ZONE configuration
option redundant.
The first patch removes them both in a mechanical way and the second patch
simplifies memory_hotplug::test_pages_in_a_zone() that had
pfn_valid_within() surrounded by more logic than simple if.
This patch (of 2):
After recent changes in freeing of the unused parts of the memory map and
rework of pfn_valid() in arm and arm64 there are no architectures that can
have holes in the memory map within a pageblock and so nothing can enable
CONFIG_HOLES_IN_ZONE which guards non trivial implementation of
pfn_valid_within().
With that, pfn_valid_within() is always hardwired to 1 and can be
completely removed.
Remove calls to pfn_valid_within() and CONFIG_HOLES_IN_ZONE.
The memory hot(un)plug documentation is outdated and incomplete. Most of
the content dates back to 2007, so it's time for a major overhaul.
Let's rewrite, reorganize and update most parts of the documentation. In
addition to memory hot(un)plug, also add some details regarding
ZONE_MOVABLE, with memory hotunplug being one of its main consumers.
Drop the file history, that information can more reliably be had from the
git log.
The style of the document is also properly fixed that e.g., "restview"
renders it cleanly now.
In the future, we might add some more details about virt users like
virtio-mem, the XEN balloon, the Hyper-V balloon and ppc64 dlpar.
Link: https://lkml.kernel.org/r/20210707073205.3835-3-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memory-hotplug.rst: remove locking details from admin-guide
Patch series "memory-hotplug.rst: complete admin-guide overhaul", v3.
This patch (of 2):
We have the same content at Documentation/core-api/memory-hotplug.rst and
it doesn't fit into the admin-guide. The documentation was accidentially
duplicated when merging.
Link: https://lkml.kernel.org/r/20210707073205.3835-1-david@redhat.com Link: https://lkml.kernel.org/r/20210707073205.3835-2-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Randy Dunlap [Tue, 7 Sep 2021 22:42:02 +0000 (15:42 -0700)]
Makefile: use -Wno-main in the full kernel tree
When using gcc (SUSE Linux) 7.5.0 (on openSUSE 15.3), I see a build
warning:
kernel/trace/trace_osnoise.c: In function 'start_kthread':
kernel/trace/trace_osnoise.c:1461:8: warning: 'main' is usually a function [-Wmain]
void *main = osnoise_main;
^~~~
Quieten that warning by using "-Wno-main". It's OK to use "main" as a
declaration name in the kernel.
Build-tested on most ARCHes.
[ v2: only do it for gcc, since clang doesn't have that particular warning ]
Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/lkml/20210813224131.25803-1-rdunlap@infradead.org/ Suggested-by: Steven Rostedt <rostedt@goodmis.org> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Daniel Bristot de Oliveira <bristot@kernel.org> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: linux-kbuild@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
projects / kernel.git / log