Re: [PATCH 14/18] prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable
From: Vlastimil Babka
Date: Fri Mar 11 2016 - 07:54:24 EST
On 02/29/2016 02:26 PM, Michal Hocko wrote:
From: Michal Hocko <mhocko@xxxxxxxx>
PR_SET_THP_DISABLE requires 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: Alex Thorlton <athorlton@xxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
---
kernel/sys.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index cf8ba545c7d3..89d5be418157 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2246,7 +2246,8 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
case PR_SET_THP_DISABLE:
if (arg3 || arg4 || arg5)
return -EINVAL;
- down_write(&me->mm->mmap_sem);
+ if (down_write_killable(&me->mm->mmap_sem))
+ return -EINTR;
if (arg2)
me->mm->def_flags |= VM_NOHUGEPAGE;
else