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>

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index c97f7940cb9553d52ba3b6c711f2dab430aea110..217bcbfde42e5138410eb993fc6b081171c60490 100644 (file)
--- 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 6c8ba25bf6bb39eed908ea23edb05c9bb605fed2..0bb7db41f4fe1a85f7059411b51d1ff24e015414 100644 (file)
--- 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 b2f2d2d668491905dbbc37c385449852a9e7fdde..2ca27b0558254bba3ae8210cd0945ee527b77621 100644 (file)
--- 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 85df1cd8d446c0b7b1fccbbcb3617175f6314289..94d3a31ab14494aeae4bfa9849125470ef0d86cd 100644 (file)
--- 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 089f3987e273a2c3f9576ef923dbd8ba8648cca5..b2f5adf838dd6324f5c44ee54864f0d84d36fc03 100644 (file)
--- 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 f9b5c10bccee96e8838484aaf6effc39b3c89bd1..8ed3c4509d846d3089f34466ed2ffebee23cf890 100644 (file)
--- 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