From: Johannes Weiner <hannes@cmpxchg.org>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
cgroups@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.cz>, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH v3] memcg: return -EINTR at bypassing try_charge().
Date: Wed, 21 Dec 2011 13:28:15 +0100 [thread overview]
Message-ID: <20111221122815.GF3870@cmpxchg.org> (raw)
In-Reply-To: <20111221192934.2751f8f1.kamezawa.hiroyu@jp.fujitsu.com>
On Wed, Dec 21, 2011 at 07:29:34PM +0900, KAMEZAWA Hiroyuki wrote:
> Thank you for review.
> I'm sorry if my response is delayed.
> ==
> >From 1e8c917c64b3947d2e54c6e5073d53d80bd97c30 Mon Sep 17 00:00:00 2001
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Date: Wed, 21 Dec 2011 16:27:25 +0900
> Subject: [PATCH] memcg: return -EINTR at bypassing try_charge().
>
> This patch is a fix for memcg-simplify-lru-handling-by-new-rule.patch
> When running testprogram and stop it by Ctrl-C, add_lru/del_lru
> will find pc->mem_cgroup is NULL and get panic. The reason
> is bypass code in try_charge().
>
> At try_charge(), it checks the thread is fatal or not as..
> fatal_signal_pending() or TIF_MEMDIE. In this case, __try_charge()
> returns 0(success) with setting *ptr as NULL.
>
> Now, lruvec are deteremined by pc->mem_cgroup. So, it's better
> to reset pc->mem_cgroup as root_mem_cgroup. This patch does
> following change in try_charge()
> 1. return -EINTR at bypassing.
> 2. set *ptr = root_mem_cgroup at bypassing.
>
> By this change, in page fault / radix-tree-insert path,
> the page will be charged against root_mem_cgroup and the thread's
> operations will go ahead without trouble. In other path,
> migration or move_account etc..., -EINTR will stop the operation.
> (may need some cleanup later..)
>
> After this change, pc->mem_cgroup will have valid pointer if
> the page is used.
>
> Changelog: v2 -> v3
> - handle !mm case in another way.
> - removed redundant commments
> - fixed move_parent bug of uninitialized pointer
> Changelog: v1 -> v2
> - returns -EINTR at bypassing.
> - change error code handling at callers.
> - changed the name of patch.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Looks good now, thanks.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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prev parent reply other threads:[~2011-12-21 12:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-19 7:51 [PATCH] memcg: reset to root_mem_cgroup at bypassing KAMEZAWA Hiroyuki
2011-12-19 20:49 ` Hugh Dickins
2011-12-20 0:24 ` Hiroyuki Kamezawa
2011-12-21 0:13 ` KAMEZAWA Hiroyuki
2011-12-21 3:25 ` Hugh Dickins
2011-12-21 4:00 ` KAMEZAWA Hiroyuki
2011-12-21 8:24 ` [PATCH v2] memcg: return -EINTR at bypassing try_charge() KAMEZAWA Hiroyuki
2011-12-21 9:57 ` Johannes Weiner
2011-12-21 10:08 ` KAMEZAWA Hiroyuki
2011-12-21 10:29 ` [PATCH v3] " KAMEZAWA Hiroyuki
2011-12-21 12:28 ` Johannes Weiner [this message]
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