From: Dmitry Ilvokhin <d@ilvokhin.com>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>,
Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
linux-kernel@vger.kernel.org, kernel-team@meta.com
Subject: Re: [PATCH RFC 1/9] hrtimer: Mark data-racy accesses to hrtimer_sleeper ->task field
Date: Tue, 4 Aug 2026 17:25:37 +0000 [thread overview]
Message-ID: <anIgkTSVJqRYgFqZ@shell.ilvokhin.com> (raw)
In-Reply-To: <20260731004019.3530210-1-paulmck@kernel.org>
On Thu, Jul 30, 2026 at 05:40:11PM -0700, Paul E. McKenney wrote:
> The hrtimer_sleeper structure's ->task field is used as a flag to indicate
> that the associated hrtimer has expired. This means that the hrtimer
> handler can be storing to this field while other code is loading from it
> to check for expiry. Note that additional races appear for hrtimers that
> can be restarted, which could be argued to be a user error. However,
> that is no reason to let the compiler introduce additional confusion.
>
> Therefore, mark data-racy accesses to the hrtimer_sleeper ->task field
> using READ_ONCE() (using a new hrtimer_sleeper_task_get() access function)
> and WRITE_ONCE() (using a new hrtimer_sleeper_task_set() access function).
>
> KCSAN located this issue.
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Dmitry Ilvokhin <d@ilvokhin.com>
next prev parent reply other threads:[~2026-08-04 17:25 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-31 0:39 [PATCH RFC 0/9] Fix data races on hrtimer_sleeper ->task field Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 1/9] hrtimer: Mark data-racy accesses to " Paul E. McKenney
2026-08-04 17:25 ` Dmitry Ilvokhin [this message]
2026-08-11 13:35 ` Thomas Gleixner
2026-08-11 19:15 ` Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 2/9] aio: Use accessor for " Paul E. McKenney
2026-07-31 12:32 ` Jan Kara
2026-07-31 12:57 ` Christian Brauner
2026-07-31 17:40 ` Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 3/9] wait: " Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 4/9] io-uring/rw: " Paul E. McKenney
2026-07-31 15:03 ` Jens Axboe
2026-07-31 17:42 ` Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 5/9] futex: Use accessor for hrtimer_sleeper ->task field in waitwake.c Paul E. McKenney
2026-08-03 15:20 ` André Almeida
2026-08-04 17:29 ` Dmitry Ilvokhin
2026-07-31 0:40 ` [PATCH RFC 6/9] timers: Use accessor for hrtimer_sleeper ->task field in sleep_timeout.c Paul E. McKenney
2026-08-04 17:31 ` Dmitry Ilvokhin
2026-07-31 0:40 ` [PATCH RFC 7/9] net: pktgen: Use accessor for hrtimer_sleeper ->task field Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 8/9] rtmutex: " Paul E. McKenney
2026-08-04 17:32 ` Dmitry Ilvokhin
2026-08-04 20:15 ` Paul E. McKenney
2026-07-31 0:40 ` [PATCH RFC 9/9] futex: Use accessor for hrtimer_sleeper ->task field in requeue Paul E. McKenney
2026-08-03 15:21 ` André Almeida
2026-08-03 15:45 ` Paul E. McKenney
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