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From: Michal Hocko <mhocko@suse.cz>
To: Jianyu Zhan <nasa4836@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Balbir Singh <bsingharora@gmail.com>,
	kamezawa.hiroyu@jp.fujitsu.com, Cgroups <cgroups@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] mm/memcontrol.c: remove meaningless while loop in mem_cgroup_iter()
Date: Tue, 22 Apr 2014 12:34:21 +0200	[thread overview]
Message-ID: <20140422103420.GI29311@dhcp22.suse.cz> (raw)
In-Reply-To: <CAHz2CGWrk3kuR=BLt2vT-8gxJVtJcj6h17ase9=1CoWXwK6a3w@mail.gmail.com>

On Tue 22-04-14 18:17:09, Jianyu Zhan wrote:
> On Tue, Apr 22, 2014 at 5:47 PM, Michal Hocko <mhocko@suse.cz> wrote:
> > What about
> >   3. last_visited == last_node in the tree
> >
> > __mem_cgroup_iter_next returns NULL and the iterator would return
> > without visiting anything.
> 
> Hi,  Michal,
> 
> yep,  if 3 last_visited == last_node, then this means we have done a round-trip,
> thus __mem_cgroup_iter_next returns NULL, in turn mem_cgroup_iter() return NULL.

Sorry, I should have been more specific that I was talking about
mem_cgroup_reclaim_cookie path where the iteration for this particular
zone and priority ended at the last node without finishing the full
roundtrip last time. This new iteration (prev==NULL) wants to continue
and it should start a new roundtrip.

Makes sense?
-- 
Michal Hocko
SUSE Labs

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  reply	other threads:[~2014-04-22 10:34 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-18 22:58 Jianyu Zhan
2014-04-22  9:47 ` Michal Hocko
2014-04-22 10:17   ` Jianyu Zhan
2014-04-22 10:34     ` Michal Hocko [this message]
2014-04-22 10:58       ` Jianyu Zhan
2014-04-22 11:48         ` Michal Hocko
2014-04-22 11:53           ` Jianyu Zhan

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