arch: mm: pass userspace fault flag to generic fault handler

Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: azurIt <azurit@pobox.sk>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index f247a3480e8e..d10d27a720c0 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -180,6 +180,10 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
         if (in_atomic() || !mm)
                 goto no_context;
 
+        if (user_mode(regs))
+                flags |= FAULT_FLAG_USER;
+        if (acc_type & VM_WRITE)
+                flags |= FAULT_FLAG_WRITE;
 retry:
         down_read(&mm->mmap_sem);
         vma = find_vma_prev(mm, address, &prev_vma);
@@ -203,8 +207,7 @@ good_area:
          * fault.
          */
 
-        fault = handle_mm_fault(mm, vma, address,
-                        flags | ((acc_type & VM_WRITE) ? FAULT_FLAG_WRITE : 0));
+        fault = handle_mm_fault(mm, vma, address, flags);
 
         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
                 return;