From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>,
linux-mm@kvack.org
Subject: Re: [PATCH 4/4] memcg: fix mem_cgroup_print_bad_page
Date: Thu, 5 Jan 2012 15:01:50 +0900 [thread overview]
Message-ID: <20120105150150.436dfce8.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <alpine.LSU.2.00.1112281623400.8257@eggly.anvils>
On Wed, 28 Dec 2011 16:26:02 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:
> If DEBUG_VM, mem_cgroup_print_bad_page() is called whenever bad_page()
> shows a "Bad page state" message, removes page from circulation, adds a
> taint and continues. This is at a very low level, often when a spinlock
> is held (sometimes when page table lock is held, for example).
>
> We want to recover from this badness, not make it worse: we must not
> kmalloc memory here, we must not do a cgroup path lookup via dubious
> pointers. No doubt that code was useful to debug a particular case
> at one time, and may be again, but take it out of the mainline kernel.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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prev parent reply other threads:[~2012-01-05 6:03 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-29 0:17 [PATCH 0/4] memcg: four fixes to current next Hugh Dickins
2011-12-29 0:20 ` [PATCH 1/4] memcg: fix split_huge_page_refcounts Hugh Dickins
2012-01-05 5:55 ` KAMEZAWA Hiroyuki
2011-12-29 0:21 ` [PATCH 2/4] memcg: fix NULL mem_cgroup_try_charge Hugh Dickins
2012-01-05 5:56 ` KAMEZAWA Hiroyuki
2011-12-29 0:23 ` [PATCH 3/4] memcg: fix page migration to reset_owner Hugh Dickins
2012-01-05 6:00 ` KAMEZAWA Hiroyuki
2011-12-29 0:26 ` [PATCH 4/4] memcg: fix mem_cgroup_print_bad_page Hugh Dickins
2012-01-05 6:01 ` KAMEZAWA Hiroyuki [this message]
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