From: Qian Cai <quic_qiancai@quicinc.com>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: <akpm@linux-foundation.org>, <david@redhat.com>,
<ying.huang@intel.com>, <songmuchun@bytedance.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/2] mm/swapfile: fix possible data races of inuse_pages
Date: Mon, 27 Jun 2022 09:47:16 -0400 [thread overview]
Message-ID: <Yrm05NQs5+tCZawR@qian> (raw)
In-Reply-To: <fe3c4834-71a6-7867-2108-eca43fde62fc@huawei.com>
On Mon, Jun 27, 2022 at 09:27:43PM +0800, Miaohe Lin wrote:
> On 2022/6/27 20:43, Qian Cai wrote:
> > On Sat, Jun 25, 2022 at 05:33:45PM +0800, Miaohe Lin wrote:
> >> si->inuse_pages could still be accessed concurrently now. The plain reads
> >> outside si->lock critical section, i.e. swap_show and si_swapinfo, which
> >> results in data races. READ_ONCE and WRITE_ONCE is used to fix such data
> >> races. Note these data races should be ok because they're just used for
> >> showing swap info.
> >
> > Was this found by kcsan? If so, it would be useful to record the exact
> > kscan report in the commit message.
>
> Sorry, it's found via code inspection.
Well, if we are going to do a WRITE_ONCE() in those places just for
documentation purpose now, I think we will need to fix all places in the mm
subsystem to be consistent.
next prev parent reply other threads:[~2022-06-27 13:48 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-25 9:33 [PATCH v3 0/2] A few cleanup and fixup patches for swap Miaohe Lin
2022-06-25 9:33 ` [PATCH v3 1/2] mm/swapfile: fix possible data races of inuse_pages Miaohe Lin
2022-06-27 1:29 ` Huang, Ying
2022-06-27 12:43 ` Qian Cai
2022-06-27 13:27 ` Miaohe Lin
2022-06-27 13:47 ` Qian Cai [this message]
2022-06-28 1:56 ` Huang, Ying
2022-06-25 9:33 ` [PATCH v3 2/2] mm/swap: remove swap_cache_info statistics Miaohe Lin
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