Tetsuo Handa wrote:
> > Users of mmap_sem which need it for write should be carefully reviewed
> > to use _killable waiting as much as possible and reduce allocations
> > requests done with the lock held to absolute minimum to reduce the risk
> > even further.
>
> It will be nice if we can have down_write_killable()/down_read_killable().
It will be nice if we can also have __GFP_KILLABLE. Although currently it can't
be perfect because reclaim functions called from __alloc_pages_slowpath() use
unkillable waits, starting from just bail out as with __GFP_NORETRY when
fatal_signal_pending(current) is true will be helpful.
So far I'm hitting no problem with testers except the one using mmap()/munmap().
I think that cmpxchg() was not needed.
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c2ab7f9..1a65739 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -483,8 +483,6 @@ static int oom_reaper(void *unused)
static void wake_oom_reaper(struct mm_struct *mm)
{
- struct mm_struct *old_mm;
-
if (!oom_reaper_th)
return;
@@ -492,14 +490,15 @@ static void wake_oom_reaper(struct mm_struct *mm)
* Make sure that only a single mm is ever queued for the reaper
* because multiple are not necessary and the operation might be
* disruptive so better reduce it to the bare minimum.
+ * Caller is serialized by oom_lock mutex.
*/
- old_mm = cmpxchg(&mm_to_reap, NULL, mm);
- if (!old_mm) {
+ if (!mm_to_reap) {
/*
* Pin the given mm. Use mm_count instead of mm_users because
* we do not want to delay the address space tear down.
*/
atomic_inc(&mm->mm_count);
+ mm_to_reap = mm;
wake_up(&oom_reaper_wait);
}
}
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>