Re: [PATCH 1/2] mm,vmscan: Kill global shrinker lock.

From: Shakeel Butt
Date: Fri Nov 17 2017 - 12:53:34 EST

On Fri, Nov 17, 2017 at 9:41 AM, Shakeel Butt <shakeelb@xxxxxxxxxx> wrote:
> On Fri, Nov 17, 2017 at 9:35 AM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>> On Tue, Nov 14, 2017 at 06:37:42AM +0900, Tetsuo Handa wrote:
>>> Since do_shrink_slab() can reschedule, we cannot protect shrinker_list
>>> using one RCU section. But using atomic_inc()/atomic_dec() for each
>>> do_shrink_slab() call will not impact so much.
>> But you could use SRCU..
> I looked into that but was advised to not go through that route due to
> SRCU behind the CONFIG_SRCU. However now I see the precedence of
> "#ifdef CONFIG_SRCU" in drivers/base/core.c and I think if we can take
> that route if even after Minchan's patch the issue persists.

Too many 'ifs' in the last sentence. I just wanted to say we can
consider SRCU if the issue persists even after Minchan's patch.