On 02/29/2016 07:07 PM, Michal Hocko wrote:
From: Michal Hocko <[email protected]>
dup_mmap needs to lock current's mm mmap_sem for write. If the waiting
task gets killed by the oom killer it would block oom_reaper from
asynchronous address space reclaim and reduce the chances of timely OOM
resolving. Wait for the lock in the killable mode and return with EINTR
if the task got killed while waiting.
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
---
kernel/fork.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index d277e83ed3e0..139968026b76 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -413,7 +413,10 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct
*oldmm)
unsigned long charge;
uprobe_start_dup_mmap();
- down_write(&oldmm->mmap_sem);
+ if (down_write_killable(&oldmm->mmap_sem)) {
+ retval = -EINTR;
+ goto fail_uprobe_end;
+ }
flush_cache_dup_mm(oldmm);
uprobe_dup_mmap(oldmm, mm);
/*
@@ -525,6 +528,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct
*oldmm)
up_write(&mm->mmap_sem);
flush_tlb_mm(oldmm);
up_write(&oldmm->mmap_sem);
+fail_uprobe_end:
uprobe_end_dup_mmap();
return retval;
fail_nomem_anon_vma_fork:
