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Re: [PATCH] mm, swap: Fix a race in free_swap_and_cache()

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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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[PATCH] mm, swap: Fix a race in free_swap_and_cache() "Huang, Ying" <ying.huang@intel.com> - 2017-03-01 15:50 +0100
  Re: [PATCH] mm, swap: Fix a race in free_swap_and_cache() Andrew Morton <akpm@linux-foundation.org> - 2017-03-04 00:00 +0100
    Re: [PATCH] mm, swap: Fix a race in free_swap_and_cache() huang ying <huang.ying.caritas@gmail.com> - 2017-03-04 13:10 +0100

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