From 871341023c771ad233620b7a1fb3d9c7031c4e5c Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Thu, 12 Sep 2013 15:13:38 -0700
Subject: [PATCH] arch: mm: do not invoke OOM killer on kernel fault OOM
Kernel faults are expected to handle OOM conditions gracefully (gup,
uaccess etc.), so they should never invoke the OOM killer. Reserve this
for faults triggered in user context when it is the only option.
Most architectures already do this, fix up the remaining few.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/arm/mm/fault.c | 14 +++++++-------
arch/arm64/mm/fault.c | 14 +++++++-------
arch/avr32/mm/fault.c | 2 +-
arch/mips/mm/fault.c | 2 ++
arch/um/kernel/trap.c | 2 ++
arch/unicore32/mm/fault.c | 14 +++++++-------
6 files changed, 26 insertions(+), 22 deletions(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index c97f7940cb955..217bcbfde42e5 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -349,6 +349,13 @@ retry:
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
return 0;
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ */
+ if (!user_mode(regs))
+ goto no_context;
+
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, call the OOM killer, and return to
@@ -359,13 +366,6 @@ retry:
return 0;
}
- /*
- * If we are in kernel mode at this point, we
- * have no context to handle this fault with.
- */
- if (!user_mode(regs))
- goto no_context;
-
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 6c8ba25bf6bb3..0bb7db41f4fe1 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -288,6 +288,13 @@ retry:
VM_FAULT_BADACCESS))))
return 0;
+ /*
+ * If we are in kernel mode at this point, we have no context to
+ * handle this fault with.
+ */
+ if (!user_mode(regs))
+ goto no_context;
+
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, call the OOM killer, and return to
@@ -298,13 +305,6 @@ retry:
return 0;
}
- /*
- * If we are in kernel mode at this point, we have no context to
- * handle this fault with.
- */
- if (!user_mode(regs))
- goto no_context;
-
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to successfully fix up
diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index b2f2d2d668491..2ca27b0558254 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -228,9 +228,9 @@ no_context:
*/
out_of_memory:
up_read(&mm->mmap_sem);
- pagefault_out_of_memory();
if (!user_mode(regs))
goto no_context;
+ pagefault_out_of_memory();
return;
do_sigbus:
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index 85df1cd8d446c..94d3a31ab1449 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -241,6 +241,8 @@ out_of_memory:
* (which will retry the fault, or kill us if we got oom-killed).
*/
up_read(&mm->mmap_sem);
+ if (!user_mode(regs))
+ goto no_context;
pagefault_out_of_memory();
return;
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 089f3987e273a..b2f5adf838dd6 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -124,6 +124,8 @@ out_of_memory:
* (which will retry the fault, or kill us if we got oom-killed).
*/
up_read(&mm->mmap_sem);
+ if (!is_user)
+ goto out_nosemaphore;
pagefault_out_of_memory();
return 0;
}
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index f9b5c10bccee9..8ed3c4509d846 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -278,6 +278,13 @@ retry:
(VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
return 0;
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ */
+ if (!user_mode(regs))
+ goto no_context;
+
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, call the OOM killer, and return to
@@ -288,13 +295,6 @@ retry:
return 0;
}
- /*
- * If we are in kernel mode at this point, we
- * have no context to handle this fault with.
- */
- if (!user_mode(regs))
- goto no_context;
-
if (fault & VM_FAULT_SIGBUS) {
/*
* We had some memory, but were unable to
--
2.39.5