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

[Christoph Hellwig]

On Fri, Nov 17, 2017 at 09:41:46AM -0800, Shakeel Butt 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.

To be honest, I'd rather always require RCU then have core kernel
code reinvent it.