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authorMichal Hocko <mhocko@suse.com>2016-05-23 16:25:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-23 17:04:14 -0700
commit91f4f94ea3f2eabb4cee68149a31e30f84a993dd (patch)
tree1f137113b14e0a66cf24a8c8a32650095f7234d9 /ipc
parent7c051267931a9be9c6620cc17b362bc6ee6dedc8 (diff)
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ipc, shm: make shmem attach/detach wait for mmap_sem killable
shmat and shmdt rely on 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 <mhocko@suse.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/shm.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 331fc1b..1328251 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1200,7 +1200,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
if (err)
goto out_fput;
- down_write(&current->mm->mmap_sem);
+ if (down_write_killable(&current->mm->mmap_sem)) {
+ err = -EINTR;
+ goto out_fput;
+ }
+
if (addr && !(shmflg & SHM_REMAP)) {
err = -EINVAL;
if (addr + size < addr)
@@ -1271,7 +1275,8 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
if (addr & ~PAGE_MASK)
return retval;
- down_write(&mm->mmap_sem);
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
/*
* This function tries to be smart and unmap shm segments that
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