[PATCH 1/2] mm, oom: skip mlocked VMAs in __oom_reap_vmas()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

As far as I can see we explicitly munlock pages everywhere before unmap
them. The only case when we don't to that is OOM-reaper.

I don't think we should bother with munlocking in this case, we can just
skip the locked VMA.

I think this patch would fix this crash:
 http://lkml.kernel.org/r/5661FBB6.6050307@oracle.com

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
---
 mm/oom_kill.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4b0a5d8b92e1..fe58d76c1215 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -447,6 +447,13 @@ static bool __oom_reap_vmas(struct mm_struct *mm)
 			continue;
 
 		/*
+		 * mlocked VMAs require explicit munlocking before unmap.
+		 * Let's keep it simple here and skip such VMAs.
+		 */
+		if (vma->vm_flags & VM_LOCKED)
+			continue;
+
+		/*
 		 * Only anonymous pages have a good chance to be dropped
 		 * without additional steps which we cannot afford as we
 		 * are OOM already.
-- 
2.6.4

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