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Commit 87134102 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Acked-by: default avatarKOSAKI 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 94bce453

arch/arm/mm/fault.c

+7 −7
Original line number Diff line number Diff line
@@ -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

arch/arm64/mm/fault.c

+7 −7
Original line number Diff line number Diff line
@@ -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

arch/avr32/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -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:

arch/mips/mm/fault.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

arch/um/kernel/trap.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

}