linux-kernel - Re: [PATCH v4] mm/vmscan: more restrictive condition for retry in do_try_to_free

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Message-ID: <20170317200023.GA16939@cmpxchg.org>
Date:   Fri, 17 Mar 2017 16:00:23 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Yisheng Xie <xieyisheng1@...wei.com>, akpm@...ux-foundation.org,
        mgorman@...e.de, vbabka@...e.cz, riel@...hat.com,
        shakeelb@...gle.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, guohanjun@...wei.com,
        qiuxishi@...wei.com
Subject: Re: [PATCH v4] mm/vmscan: more restrictive condition for retry in
 do_try_to_free_pages

On Fri, Mar 17, 2017 at 07:45:27PM +0100, Michal Hocko wrote:
> On Fri 17-03-17 14:39:28, Johannes Weiner wrote:
> > On Wed, Mar 15, 2017 at 07:36:48PM +0800, Yisheng Xie wrote:
> > > @@ -2808,7 +2813,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
> > >  		return 1;
> > >  
> > >  	/* Untapped cgroup reserves?  Don't OOM, retry. */
> > > -	if (!sc->may_thrash) {
> > > +	if (sc->memcg_low_protection && !sc->may_thrash) {
> > 
> > 	if (sc->memcg_low_skipped) {
> > 		[...]
> > 		sc->memcg_low_reclaim = 1;
> 
> you need to set memcg_low_skipped = 0 here, right? Otherwise we do not
> have break out of the loop. Or am I missing something?

Oops, you're right of course. That needs to be reset.