From: Seth Jennings <sjenning@linux.vnet.ibm.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Nitin Gupta <ngupta@vflare.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Dan Magenheimer <dan.magenheimer@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
devel@driverdev.osuosl.org, xiaoguangrong@linux.vnet.ibm.com
Subject: Re: [PATCH 0/2] revert changes to zcache_do_preload()
Date: Thu, 23 Aug 2012 17:10:00 -0500 [thread overview]
Message-ID: <5036AA38.6010400@linux.vnet.ibm.com> (raw)
In-Reply-To: <20120823205648.GA2066@barrios>
On 08/23/2012 03:56 PM, Minchan Kim wrote:
> Hi Seth,
>
> On Thu, Aug 23, 2012 at 10:33:09AM -0500, Seth Jennings wrote:
>> This patchset fixes a regression in 3.6 by reverting two dependent
>> commits that made changes to zcache_do_preload().
>>
>> The commits undermine an assumption made by tmem_put() in
>> the cleancache path that preemption is disabled. This change
>> introduces a race condition that can result in the wrong page
>> being returned by tmem_get(), causing assorted errors (segfaults,
>> apparent file corruption, etc) in userspace.
>>
>> The corruption was discussed in this thread:
>> https://lkml.org/lkml/2012/8/17/494
>
> I think changelog isn't enough to explain what's the race.
> Could you write it down in detail?
I didn't come upon this solution via code inspection, but
rather through discovering that the issue didn't exist in
v3.5 and just looking at the changes since then.
> And you should Cc'ed Xiao who is author of reverted patch.
Thanks for adding Xiao. I meant to do this. For some reason
I thought that you submitted that patchset :-/
My bad.
Seth
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next prev parent reply other threads:[~2012-08-23 22:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-23 15:33 [PATCH 0/2] revert changes to zcache_do_preload() Seth Jennings
2012-08-23 15:33 ` [PATCH 1/2] Revert "staging: zcache: cleanup zcache_do_preload and zcache_put_page" Seth Jennings
2012-08-23 15:33 ` [PATCH 2/2] Revert "staging: zcache: optimize zcache_do_preload" Seth Jennings
2012-08-23 20:56 ` [PATCH 0/2] revert changes to zcache_do_preload() Minchan Kim
2012-08-23 22:10 ` Seth Jennings [this message]
2012-08-23 23:28 ` Minchan Kim
2012-08-24 2:21 ` Xiao Guangrong
2012-08-24 20:57 ` Seth Jennings
2012-08-29 17:42 ` Seth Jennings
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