]> git.baikalelectronics.ru Git - kernel.git/commit
mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()
authorRoman Gushchin <guro@fb.com>
Sat, 16 Nov 2019 01:34:46 +0000 (17:34 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 16 Nov 2019 02:34:00 +0000 (18:34 -0800)
commit906aeb0e7007d5ec6e37767602fc805987bef474
tree0f2ae5db5b9db9b3a1c84d710a73331e47b1788f
parent8a6a7031c190aa24593593b7d2b5ef54e3ce5816
mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()

An exiting task might belong to an offline cgroup.  In this case an
attempt to grab a cgroup reference from the task can end up with an
infinite loop in hugetlb_cgroup_charge_cgroup(), because neither the
cgroup will become online, neither the task will be migrated to a live
cgroup.

Fix this by switching over to css_tryget().  As css_tryget_online()
can't guarantee that the cgroup won't go offline, in most cases the
check doesn't make sense.  In this particular case users of
hugetlb_cgroup_charge_cgroup() are not affected by this change.

A similar problem is described by commit 1dd10c66c8c8 ("cgroup: Use
css_tryget() instead of css_tryget_online() in task_get_css()").

Link: http://lkml.kernel.org/r/20191106225131.3543616-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hugetlb_cgroup.c