From: "Paul Menage" <menage@google.com>
To: balbir@linux.vnet.ibm.com
Cc: Pavel Emelianov <xemul@openvz.org>,
Hugh Dickins <hugh@veritas.com>,
Sudhir Kumar <skumar@linux.vnet.ibm.com>,
YAMAMOTO Takashi <yamamoto@valinux.co.jp>,
lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org,
taka@valinux.co.jp, linux-mm@kvack.org,
David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [-mm] Add an owner to the mm_struct (v2)
Date: Fri, 28 Mar 2008 07:06:52 -0700 [thread overview]
Message-ID: <6599ad830803280706j54376243if56ccca0281f685d@mail.gmail.com> (raw)
In-Reply-To: <47ECEA8F.5060505@linux.vnet.ibm.com>
On Fri, Mar 28, 2008 at 5:54 AM, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>
> Thinking more, I don't think it makes sense for us to overload task_lock() to do
> the mm->owner handling (we don't want to mix lock domains). task_lock() is used
> for several things
>
> 1. We don't want to make task_lock() rules more complicated by having it protect
> an mm member to save space
> 2. We don't want more contention on task_lock()
>
This isn't to save space, it's to provide correctness. We *have* to
hold task_lock(new_owner) before setting mm->owner = new_owner,
otherwise we have no guarantee that new_owner is still a user of mm.
Paul
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next prev parent reply other threads:[~2008-03-28 14:06 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-28 8:23 Balbir Singh
2008-03-28 9:41 ` Jiri Slaby
2008-03-28 9:43 ` Jiri Slaby
2008-03-28 10:11 ` Balbir Singh
2008-03-28 10:48 ` KAMEZAWA Hiroyuki
2008-03-28 10:51 ` Balbir Singh
2008-03-28 11:06 ` KAMEZAWA Hiroyuki
2008-03-28 10:55 ` KAMEZAWA Hiroyuki
2008-03-28 10:52 ` Balbir Singh
2008-03-28 11:04 ` Paul Menage
2008-03-28 11:15 ` KAMEZAWA Hiroyuki
2008-03-28 11:21 ` KAMEZAWA Hiroyuki
2008-03-28 11:01 ` Paul Menage
2008-03-28 12:36 ` Balbir Singh
2008-03-28 12:54 ` Balbir Singh
2008-03-28 14:06 ` Paul Menage [this message]
2008-03-28 14:05 ` Paul Menage
2008-03-28 14:52 ` Balbir Singh
2008-03-28 15:38 ` Paul Menage
2008-03-28 18:10 ` Balbir Singh
2008-03-28 18:52 ` Paul Menage
2008-03-29 1:02 ` Balbir Singh
2008-03-29 5:46 ` Balbir Singh
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