From: Andrew Morton <akpm@linux-foundation.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>, Shaohua Li <shli@kernel.org>,
Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
Tim Chen <tim.c.chen@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm, swap: Fix a race in free_swap_and_cache()
Date: Fri, 3 Mar 2017 14:43:29 -0800 [thread overview]
Message-ID: <20170303144329.94d47b1015ba2f18f64c5893@linux-foundation.org> (raw)
In-Reply-To: <20170301143905.12846-1-ying.huang@intel.com>
On Wed, 1 Mar 2017 22:38:09 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
> Before using cluster lock in free_swap_and_cache(), the
> swap_info_struct->lock will be held during freeing the swap entry and
> acquiring page lock, so the page swap count will not change when
> testing page information later. But after using cluster lock, the
> cluster lock (or swap_info_struct->lock) will be held only during
> freeing the swap entry. So before acquiring the page lock, the page
> swap count may be changed in another thread. If the page swap count
> is not 0, we should not delete the page from the swap cache. This is
> fixed via checking page swap count again after acquiring the page
> lock.
What are the user-visible runtime effects of this bug? Please always
include this info when fixing things, thanks.
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next prev parent reply other threads:[~2017-03-03 22:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-01 14:38 [PATCH] mm, swap: Fix a race in free_swap_and_cache() Huang, Ying
2017-03-03 22:43 ` Andrew Morton [this message]
2017-03-04 11:53 ` huang ying
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