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>

1 files changed, 7 insertions, 7 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index c97f7940cb95..217bcbfde42e 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