prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable

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. Signed-off-by: Michal Hocko <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Acked-by: Alex Thorlton <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ericholscher · May 24, 2016 · 17b0573 · 17b0573
1 parent f268dfe
commit 17b0573
Showing 1 changed file with 2 additions and 1 deletion.
diff --git 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