arch: mm: do not invoke OOM killer on kernel fault OOM

commit 871341023c771ad233620b7a1fb3d9c7031c4e5c upstream.

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>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 5dbf13f954f6f493aaae525d4f3b93282ac88f75..2ebf4f6dc026d8f152b6675cd26d2c2a61d07a2c 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 f51d669c8ebdd0397e2d1cb132e0cd7f4b9b7295..f5f0c70da7a155f1b94628a0cd617bea34995724 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 0fead53d1c26b261affa89d00c1fa06844f9e602..da47e9b7f425ba106008a116fbe579b1596249c6 100644 (file)
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -240,6 +240,8 @@ 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