On Tue, 9 Aug 2011 12:09:44 +0200
Michal Hocko [off-list ref] wrote:

On Tue 09-08-11 18:53:13, KAMEZAWA Hiroyuki wrote:

quoted

On Tue, 9 Aug 2011 11:45:03 +0200
Michal Hocko [off-list ref] wrote:

quoted

On Tue 09-08-11 18:32:16, KAMEZAWA Hiroyuki wrote:

quoted

On Tue, 9 Aug 2011 11:31:50 +0200
Michal Hocko [off-list ref] wrote:

quoted

What do you think about the half backed patch bellow? I didn't manage to
test it yet but I guess it should help. I hate asymmetry of drain_lock
locking (it is acquired somewhere else than it is released which is
not). I will think about a nicer way how to do it.
Maybe I should also split the rcu part in a separate patch.

What do you think?

I'd like to revert 8521fc50 first and consider total design change
rather than ad-hoc fix.

Agreed. Revert should go into 3.0 stable as well. Although the global
mutex is buggy we have that behavior for a long time without any reports.
We should address it but it can wait for 3.2.

I will send the revert request to Linus.

quoted

What "buggy" means here ? "problematic" or "cause OOps ?"

I have described that in an earlier email. Consider pathological case
when CPU0 wants to async. drain a memcg which has a lot of cached charges while
CPU1 is already draining so it holds the mutex. CPU0 backs off so it has
to reclaim although we could prevent from it by getting rid of cached
charges. This is not critical though.

That problem should be fixed by background reclaim.
I'll do it after fixing numascan. (and dirty-ratio problem...)

Thanks,
-Kame

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>