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From: Michal Hocko <mhocko@suse.cz>
To: Hillf Danton <dhillf@gmail.com>
Cc: Hugh Dickins <hughd@google.com>,
	Balbir Singh <bsingharora@gmail.com>,
	David Rientjes <rientjes@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: memcg: keep root group unchanged if fail to create new
Date: Mon, 12 Dec 2011 14:11:18 +0100	[thread overview]
Message-ID: <20111212131118.GA15249@tiehlicka.suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.00.1112111520510.2297@eggly>

On Sun 11-12-11 15:39:43, Hugh Dickins wrote:
> On Sun, 11 Dec 2011, Hillf Danton wrote:
> 
> > If the request is not to create root group and we fail to meet it,
> > we'd leave the root unchanged.
> 
> I didn't understand that at first: please say "we should" rather
> than "we'd", which I take to be an abbreviation for "we would".
> 
> > 
> > Signed-off-by: Hillf Danton <dhillf@gmail.com>
> 
> Yes indeed, well caught:
> Acked-by: Hugh Dickins <hughd@google.com>
> 
> I wonder what was going through the author's mind when he wrote it
> that way?  I wonder if it's one of those bugs that creeps in when
> you start from a perfectly functional patch, then make refinements
> to suit feedback from reviewers.
> 
> On which topic: wouldn't this patch be better just to move the
> "root_mem_cgroup = memcg;" two lines lower down (and of course
> remove free_out's "root_mem_cgroup = NULL;" as you already did)?

Yes would look nicer.

> I can't see mem_cgroup_soft_limit_tree_init() relying on
> root_mem_cgroup at all.

It doesn't but it still needs some love to handle error case properly
AFAICS. We do not deallocate softlimit trees for nodes that succeeded.

[...]

Hilf could you update the patch please?
-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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  parent reply	other threads:[~2011-12-12 13:11 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-11  1:19 [PATCH] mm: memcg: keep root group unchanged if fail to create new Hillf Danton
2011-12-11 23:39 ` Hugh Dickins
2011-12-12 12:48   ` Hillf Danton
2011-12-12 13:11   ` Michal Hocko [this message]
2011-12-12 13:49     ` Hillf Danton
2011-12-12 14:07       ` Michal Hocko
2011-12-12 14:09         ` [PATCH] memcg: clean up soft_limit_tree properly new Michal Hocko
2011-12-13 14:08           ` Johannes Weiner
2011-12-13 14:19             ` Michal Hocko
2011-12-14  1:00           ` Andrew Morton
2011-12-14  1:16             ` KAMEZAWA Hiroyuki
2011-12-13 14:05       ` [PATCH] mm: memcg: keep root group unchanged if fail to create new Johannes Weiner
2011-12-12  0:52 ` KAMEZAWA Hiroyuki

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