Date: Fri, 17 Mar 2017 16:00:23 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Yisheng Xie <xieyisheng1@huawei.com>, akpm@linux-foundation.org,
        mgorman@suse.de, vbabka@suse.cz, riel@redhat.com, shakeelb@google.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org, guohanjun@huawei.com,
        qiuxishi@huawei.com
Subject: Re: [PATCH v4] mm/vmscan: more restrictive condition for retry in
 do_try_to_free_pages
Message-ID: <20170317200023.GA16939@cmpxchg.org>
References: <1489577808-19228-1-git-send-email-xieyisheng1@huawei.com>
 <20170317183928.GA12281@cmpxchg.org>
 <20170317184527.GC23957@dhcp22.suse.cz>
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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.