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From: Li Zefan <lizefan@huawei.com>
To: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	<containers@lists.linux-foundation.org>,
	<cgroups@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: Is not locking task_lock in cgroup_fork() safe?
Date: Fri, 19 Oct 2012 16:50:34 +0800	[thread overview]
Message-ID: <5081145A.2010307@huawei.com> (raw)
In-Reply-To: <20121019005801.GF13370@google.com>

On 2012/10/19 8:58, Tejun Heo wrote:
> Hello, again.
> 
> On Thu, Oct 18, 2012 at 05:38:35PM -0700, Tejun Heo wrote:
>> Even if there isn't an actual race, the comment is dead wrong.  I'm
>> reverting the following three patches.  Let's try again later.
>>
>>   7e381b0eb1 ("cgroup: Drop task_lock(parent) on cgroup_fork()")
>>   7e3aa30ac8 ("cgroup: Remove task_lock() from cgroup_post_fork()")
> 
> So, after some more looking, I think the following is correct and
> doesn't need to be reverted.  It's depending on threadgroup locking
> from migration path to synchronize against exit path which is always
> performed.
> 
>>   c84cdf75cc ("cgroup: Remove unnecessary task_lock before fetching css_set on migration")
> 
> Frederic, were you trying to say that the above commit is correct?
> Li, do you agree?
> 

This one does look innocent.


  reply	other threads:[~2012-10-19  8:51 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20121008020000.GB2575@localhost>
     [not found] ` <CAFTL4hzXWtzp7megsCAEuak5=_2SWmp9age-+wrpyQAU4BRZ0w@mail.gmail.com>
     [not found]   ` <20121016193341.GD16166@google.com>
2012-10-18 14:50     ` Is not locking task_lock in cgroup_fork() safe? Frederic Weisbecker
2012-10-18 20:07       ` Tejun Heo
2012-10-18 20:53         ` Frederic Weisbecker
2012-10-19  0:38           ` Tejun Heo
2012-10-19  0:58             ` Tejun Heo
2012-10-19  8:50               ` Li Zefan [this message]
     [not found] ` <20121019005922.GG13370@google.com>
     [not found]   ` <CAFTL4hz82==b3ioSMhbKzh0CN1ivR7RQMKKMFFWu5PHPjg=Bfg@mail.gmail.com>
     [not found]     ` <20121019193808.GL13370@google.com>
2012-10-19 19:44       ` [PATCH cgroup/for-3.7-fixes 1/2] Revert "cgroup: Remove task_lock() from cgroup_post_fork()" Frederic Weisbecker
2012-10-19 21:07         ` Tejun Heo
2012-10-20 18:21           ` Frederic Weisbecker
2012-10-20 18:23             ` Frederic Weisbecker
2012-10-20 22:37             ` Tejun Heo
2012-10-22  9:30               ` Frederic Weisbecker

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