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From: Andrea Parri <parri.andrea@gmail.com>
To: KunWu Chan <kunwu.chan@gmail.com>
Cc: Andrea Parri <parri.andrea@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Joel Fernandes <joelagnelf@nvidia.com>,
	Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun@kernel.org>,
	Uladzislau Rezki <urezki@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang@linux.dev>, Gary Guo <gary@garyguo.net>,
	Bradley Morgan <brads@mainlining.org>,
	rcu@vger.kernel.org, lkmm@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH -rcu/dev 0/4] hazptrtorture: Fix shutdown hang and catch slot owner race
Date: Thu, 29 Oct 2026 15:48:53 +0100	[thread overview]
Message-ID: <20261029144855.213308-1-parri.andrea@gmail.com> (raw)
In-Reply-To: <CAN_Opa8OyyuveYo7VyfQb4rDtUmw_m-25OSXSqwpzfOnGqwEpQ@mail.gmail.com>

On Thu, Oct 29, 2026 at 05:58:27PM +0800, KunWu Chan wrote:
> I ran into both issues independently while developing new shared-scan
> hazptr series and its torture-test scenarios.

Thank you for testing these, and for the arm64 data points!

[...]

> Paul's concern about `torture_must_stop()` is valid: `fullstop` can make the
> drainer exit before the readers have stopped, so its exit-time flush is not
> necessarily final. The reader-exit approach looks worth testing against both
> the forced-slowpath case and the PREEMPT scenario Andrea reported.

do_pending does leave its loop then, but v1's for_each_possible_cpu()
pass comes after torture_kthread_stopping(), which returns only once
hazptr_torture_cleanup() stops do_pending, after the readers.  Either
way, I have been testing Paul's suggestion of a pass after each
reader's loop, without v1's pass in do_pending.

[...]

> These tests independently reproduced both issues in my setup. I'll check the
> final cleanup approach against the forced-slowpath scenario as the
> series settles.

That would be very helpful, thank you.

Thanks,
  Andrea

      reply	other threads:[~2026-10-29 14:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-27 16:38 Andrea Parri
2026-10-27 16:38 ` [PATCH -rcu/dev 1/4] hazptrtorture: Release all deferred hazard pointers before stopping Andrea Parri
2026-10-28 17:26   ` Paul E. McKenney
2026-10-28 23:51     ` Paul E. McKenney
2026-10-29 14:47       ` Andrea Parri
2026-10-27 16:38 ` [PATCH -rcu/dev 2/4] hazptr: Check per-CPU slot owner with CONFIG_HAZPTR_DEBUG Andrea Parri
2026-10-27 16:38 ` [PATCH -rcu/dev 3/4] hazptr: Do not warn when a backup slot is released on another CPU Andrea Parri
2026-10-28 17:30   ` Bradley Morgan
2026-10-27 16:38 ` [PATCH -rcu/dev 4/4] hazptrtorture: Nest a second hazard pointer in readers Andrea Parri
2026-10-29  9:58 ` [PATCH -rcu/dev 0/4] hazptrtorture: Fix shutdown hang and catch slot owner race KunWu Chan
2026-10-29 14:48   ` Andrea Parri [this message]

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