From: Davidlohr Bueso <dave@stgolabs.net>
To: Dave Hansen <dave@sr71.net>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, dave.hansen@linux.intel.com
Subject: Re: [PATCH] mm: fix overly aggressive shmdt() when calls span multiple segments
Date: Fri, 14 Nov 2014 00:20:38 -0800 [thread overview]
Message-ID: <1415953238.4534.2.camel@linux-t7sj.site> (raw)
In-Reply-To: <20141104000633.F35632C6@viggo.jf.intel.com>
On Mon, 2014-11-03 at 16:06 -0800, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> This is a highly-contrived scenario. But, a single shmdt() call
> can be induced in to unmapping memory from mulitple shm segments.
> Example code is here:
>
> http://www.sr71.net/~dave/intel/shmfun.c
>
> The fix is pretty simple: Record the 'struct file' for the first
> VMA we encounter and then stick to it. Decline to unmap anything
> not from the same file and thus the same segment.
>
> I found this by inspection and the odds of anyone hitting this in
> practice are pretty darn small.
>
> Lightly tested, but it's a pretty small patch.
Passed shmdt ltp tests, fwiw.
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
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prev parent reply other threads:[~2014-11-14 8:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 0:06 [PATCH] mm: fix overly aggressive shmdt() when calls span multiple segments Dave Hansen
2014-11-04 22:20 ` Andrew Morton
2014-11-14 8:20 ` Davidlohr Bueso [this message]
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