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, 6 insertions, 4 deletions

diff --git a/arch/frv/mm/fault.c b/arch/frv/mm/fault.c
index 331c1e2cfb67..9a66372fc7c7 100644
--- a/arch/frv/mm/fault.c
+++ b/arch/frv/mm/fault.c
@@ -34,11 +34,11 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
         struct vm_area_struct *vma;
         struct mm_struct *mm;
         unsigned long _pme, lrai, lrad, fixup;
+        unsigned long flags = 0;
         siginfo_t info;
         pgd_t *pge;
         pud_t *pue;
         pte_t *pte;
-        int write;
         int fault;
 
 #if 0
@@ -81,6 +81,9 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
         if (in_atomic() || !mm)
                 goto no_context;
 
+        if (user_mode(__frame))
+                flags |= FAULT_FLAG_USER;
+
         down_read(&mm->mmap_sem);
 
         vma = find_vma(mm, ear0);
@@ -129,7 +132,6 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
  */
  good_area:
         info.si_code = SEGV_ACCERR;
-        write = 0;
         switch (esr0 & ESR0_ATXC) {
         default:
                 /* handle write to write protected page */
@@ -140,7 +142,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
 #endif
                 if (!(vma->vm_flags & VM_WRITE))
                         goto bad_area;
-                write = 1;
+                flags |= FAULT_FLAG_WRITE;
                 break;
 
                  /* handle read from protected page */
@@ -162,7 +164,7 @@ asmlinkage void do_page_fault(int datammu, unsigned long esr0, unsigned long ear
          * make sure we exit gracefully rather than endlessly redo
          * the fault.
          */
-        fault = handle_mm_fault(mm, vma, ear0, write ? FAULT_FLAG_WRITE : 0);
+        fault = handle_mm_fault(mm, vma, ear0, flags);
         if (unlikely(fault & VM_FAULT_ERROR)) {
                 if (fault & VM_FAULT_OOM)
                         goto out_of_memory;