From: Weijie Yang <weijie.yang.kh@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>,
sjenning@linux.vnet.ibm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [BUG REPORT] ZSWAP: theoretical race condition issues
Date: Wed, 25 Sep 2013 16:09:04 +0800 [thread overview]
Message-ID: <CAL1ERfP70oz=tbVEAfDhgNzgLsvnpbWeOCPOMBpmKTUn0v_Lfg@mail.gmail.com> (raw)
In-Reply-To: <20130821074939.GE3022@bbox>
I think I find a new issue, for integrity of this mail thread, I reply
to this mail.
It is a concurrence issue either, when duplicate store and reclaim
concurrentlly.
zswap entry x with offset A is already stored in zswap backend.
Consider the following scenario:
thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page)
thread 1: store new page with the same offset A, alloc a new zswap entry y.
store finished. shrink_page_list() call __remove_mapping(), and now
it is not in swap_cache
thread 0: zswap_get_swap_cache_page called. old page data is added to swap_cache
Now, swap cache has old data rather than new data for offset A.
error will happen If do_swap_page() get page from swap_cache.
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next prev parent reply other threads:[~2013-09-25 8:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-18 16:14 [BUG REPORT] ZSWAP: theoretical race condition issues Weijie Yang
2013-08-19 2:17 ` Bob Liu
2013-08-19 5:47 ` Minchan Kim
2013-08-20 15:22 ` Weijie Yang
2013-08-21 12:11 ` Bob Liu
2013-08-20 15:30 ` Weijie Yang
2013-08-21 7:49 ` Minchan Kim
2013-09-25 8:09 ` Weijie Yang [this message]
2013-09-25 8:31 ` Bob Liu
2013-09-25 9:33 ` Weijie Yang
2013-09-25 10:02 ` Bob Liu
2013-09-26 2:06 ` Weijie Yang
2013-09-26 5:58 ` Minchan Kim
2013-09-26 7:26 ` Weijie Yang
2013-09-26 7:57 ` Minchan Kim
2013-09-26 8:48 ` Weijie Yang
2013-09-26 9:56 ` Bob Liu
2013-09-27 4:58 ` Minchan Kim
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