From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: frederic@kernel.org, neeraj.iitr10@gmail.com, urezki@gmail.com,
joelagnelf@nvidia.com, boqun.feng@gmail.com, rcu@vger.kernel.org,
Kumar Kartikeya Dwivedi <memxor@gmail.com>
Subject: Re: Next-level bug in SRCU implementation of RCU Tasks Trace + PREEMPT_RT
Date: Thu, 19 Mar 2026 11:51:51 +0100 [thread overview]
Message-ID: <20260319105151.Rtzk9nUj@linutronix.de> (raw)
In-Reply-To: <d3d119d8-7e41-4f22-a3c9-f7feff059a27@paulmck-laptop>
On 2026-03-19 03:43:17 [-0700], Paul E. McKenney wrote:
> On Thu, Mar 19, 2026 at 03:05:40AM -0700, Paul E. McKenney wrote:
> > On Thu, Mar 19, 2026 at 09:55:48AM +0100, Sebastian Andrzej Siewior wrote:
> > > On 2026-03-18 11:48:56 [-0700], Paul E. McKenney wrote:
> > > > We would need a lockless enqueue, which we have in llist.h.
> > >
> > > Only if CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG. Otherwise you must not
> > > provide call_rcu_nmi().
> >
> > I *think* that BPF is provided only in such architectures, so agreed.
>
> Plus srcu_read_lock_fast() uses atomic_long_inc(), which is supposed to
> be NMI-safe anyway, correct?
I am not aware of any NMI restrictions for the atomic ops, just cmpxchg.
> Thanx, Paul
Sebastian
next prev parent reply other threads:[~2026-03-19 10:51 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-17 13:34 Next-level bug in SRCU implementation of RCU Tasks Trace + PREEMPT_RT Paul E. McKenney
2026-03-18 10:50 ` Sebastian Andrzej Siewior
2026-03-18 11:49 ` Paul E. McKenney
2026-03-18 14:43 ` Sebastian Andrzej Siewior
2026-03-18 15:43 ` Paul E. McKenney
2026-03-18 16:04 ` Sebastian Andrzej Siewior
2026-03-18 16:32 ` Paul E. McKenney
2026-03-18 16:42 ` Boqun Feng
2026-03-18 18:45 ` Paul E. McKenney
2026-03-18 16:47 ` Sebastian Andrzej Siewior
2026-03-18 18:48 ` Paul E. McKenney
2026-03-19 8:55 ` Sebastian Andrzej Siewior
2026-03-19 10:05 ` Paul E. McKenney
2026-03-19 10:43 ` Paul E. McKenney
2026-03-19 10:51 ` Sebastian Andrzej Siewior [this message]
2026-03-18 15:51 ` Boqun Feng
2026-03-18 18:42 ` Paul E. McKenney
2026-03-18 20:04 ` Joel Fernandes
2026-03-18 20:11 ` Kumar Kartikeya Dwivedi
2026-03-18 20:25 ` Joel Fernandes
2026-03-18 21:52 ` Boqun Feng
2026-03-18 21:55 ` Boqun Feng
2026-03-18 22:15 ` Boqun Feng
2026-03-18 22:52 ` Joel Fernandes
2026-03-18 23:27 ` Boqun Feng
2026-03-19 1:08 ` Boqun Feng
2026-03-19 9:03 ` Sebastian Andrzej Siewior
2026-03-19 16:27 ` Boqun Feng
2026-03-19 16:33 ` Sebastian Andrzej Siewior
2026-03-19 16:48 ` Boqun Feng
2026-03-19 16:59 ` Kumar Kartikeya Dwivedi
2026-03-19 17:27 ` Boqun Feng
2026-03-19 18:41 ` Kumar Kartikeya Dwivedi
2026-03-19 20:14 ` Boqun Feng
2026-03-19 20:21 ` Joel Fernandes
2026-03-19 20:39 ` Boqun Feng
2026-03-20 15:34 ` Paul E. McKenney
2026-03-20 15:59 ` Boqun Feng
2026-03-20 16:24 ` Paul E. McKenney
2026-03-20 16:57 ` Boqun Feng
2026-03-20 17:54 ` Joel Fernandes
2026-03-20 18:14 ` [PATCH] rcu: Use an intermediate irq_work to start process_srcu() Boqun Feng
2026-03-20 19:18 ` Joel Fernandes
2026-03-20 20:47 ` Andrea Righi
2026-03-20 20:54 ` Boqun Feng
2026-03-20 21:00 ` Andrea Righi
2026-03-20 21:02 ` Andrea Righi
2026-03-20 21:06 ` Boqun Feng
2026-03-20 22:29 ` [PATCH v2] " Boqun Feng
2026-03-23 21:09 ` Joel Fernandes
2026-03-23 22:18 ` Boqun Feng
2026-03-23 22:50 ` Joel Fernandes
2026-03-24 11:27 ` Frederic Weisbecker
2026-03-24 14:56 ` Joel Fernandes
2026-03-24 14:56 ` Alexei Starovoitov
2026-03-24 17:36 ` Boqun Feng
2026-03-24 18:40 ` Joel Fernandes
2026-03-24 19:23 ` Paul E. McKenney
2026-03-26 19:12 ` patchwork-bot+netdevbpf
2026-03-21 4:27 ` [PATCH] " Zqiang
2026-03-21 18:15 ` Boqun Feng
2026-03-21 10:10 ` Paul E. McKenney
2026-03-21 17:15 ` Boqun Feng
2026-03-21 17:41 ` Paul E. McKenney
2026-03-21 18:06 ` Boqun Feng
2026-03-21 19:31 ` Paul E. McKenney
2026-03-21 19:45 ` Boqun Feng
2026-03-21 20:07 ` Paul E. McKenney
2026-03-21 20:08 ` Boqun Feng
2026-03-22 10:09 ` Paul E. McKenney
2026-03-22 16:16 ` Boqun Feng
2026-03-22 17:09 ` Paul E. McKenney
2026-03-22 17:31 ` Boqun Feng
2026-03-22 17:44 ` Paul E. McKenney
2026-03-22 18:17 ` Boqun Feng
2026-03-22 19:47 ` Paul E. McKenney
2026-03-22 20:26 ` Boqun Feng
2026-03-23 7:50 ` Paul E. McKenney
2026-03-20 18:20 ` Next-level bug in SRCU implementation of RCU Tasks Trace + PREEMPT_RT Boqun Feng
2026-03-20 23:11 ` Paul E. McKenney
2026-03-21 3:29 ` Paul E. McKenney
2026-03-21 17:03 ` [RFC PATCH] rcu-tasks: Avoid using mod_timer() in call_rcu_tasks_generic() Boqun Feng
2026-03-23 15:17 ` Boqun Feng
2026-03-23 20:37 ` Joel Fernandes
2026-03-23 21:50 ` Kumar Kartikeya Dwivedi
2026-03-23 22:13 ` Boqun Feng
2026-03-20 16:15 ` Next-level bug in SRCU implementation of RCU Tasks Trace + PREEMPT_RT Boqun Feng
2026-03-20 16:24 ` Paul E. McKenney
2026-03-19 17:02 ` Sebastian Andrzej Siewior
2026-03-19 17:44 ` Boqun Feng
2026-03-19 18:42 ` Joel Fernandes
2026-03-19 20:20 ` Boqun Feng
2026-03-19 20:26 ` Joel Fernandes
2026-03-19 20:45 ` Joel Fernandes
2026-03-19 10:02 ` Paul E. McKenney
2026-03-19 14:34 ` Boqun Feng
2026-03-19 16:10 ` Paul E. McKenney
2026-03-18 23:56 ` Kumar Kartikeya Dwivedi
2026-03-19 0:26 ` Zqiang
2026-03-19 1:13 ` Boqun Feng
2026-03-19 2:47 ` Joel Fernandes
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