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Sat, 27 Jun 2026 03:52:28 -0700 (PDT) Message-ID: Date: Sat, 27 Jun 2026 18:52:26 +0800 Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] md: protect read mddev->recovery in md_sync_action() To: Abd-Alrhman Masalkhi , Chen Cheng , linux-raid@vger.kernel.org, yukuai@fygo.io Cc: linux-kernel@vger.kernel.org References: <20260627102909.141036-1-chencheng@fnnas.com> From: Chen Cheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/6/27 18:46, Abd-Alrhman Masalkhi 写道: > On Sat, Jun 27, 2026 at 18:29 +0800, Chen Cheng wrote: >> From: Chen Cheng >> >> md_sync_action() read mddev->recovery in lockless path, use READ_ONCE() >> instead of u64 plain read. >> > unisgned long is not always u64... > I can not see what it fixes, is this just to silence KCSAN? If so, > please say so in the commit message. I need to find KCSAN report , I lost this one, but I think it's easy to find locklessly path to call md_sync_action(), so. READ_ONCE is need. > >> Fixes: e792a4c2156a3 ("md: add new helpers for sync_action") >> >> Signed-off-by: Chen Cheng >> --- >> drivers/md/md.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/md/md.c b/drivers/md/md.c >> index c5c50640b684..f4415c1a79d9 100644 >> --- a/drivers/md/md.c >> +++ b/drivers/md/md.c >> @@ -5074,11 +5074,11 @@ static enum sync_action md_get_active_sync_action(struct mddev *mddev) >> return is_recover ? ACTION_RECOVER : ACTION_IDLE; >> } >> >> enum sync_action md_sync_action(struct mddev *mddev) >> { >> - unsigned long recovery = mddev->recovery; >> + unsigned long recovery = READ_ONCE(mddev->recovery); >> enum sync_action active_action; >> >> /* >> * frozen has the highest priority, means running sync_thread will be >> * stopped immediately, and no new sync_thread can start. >> -- >> 2.54.0 >> >