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From: John Ogness <john.ogness@linutronix.de>
To: paulmck@kernel.org
Cc: Frederic Weisbecker <frederic@kernel.org>,
	rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@fb.com, rostedt@goodmis.org, tglx@linutronix.de,
	pmladek@suse.com
Subject: Re: [PATCH v2 rcu 0/8] NMI-safe SRCU reader API
Date: Thu, 27 Oct 2022 11:37:46 +0206	[thread overview]
Message-ID: <874jvpehod.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <20221024134727.GV5600@paulmck-ThinkPad-P17-Gen-1>

Hi Paul,

I am running some tests using srcunmisafe.2022.10.21a and I am hitting
the WARN_ONCE in srcu_check_nmi_safety():

[    1.836703][    T1] rcu: Hierarchical SRCU implementation.
[    1.836707][    T1] rcu:     Max phase no-delay instances is 1000.
[    1.836844][   T15] ------------[ cut here ]------------
[    1.836846][   T15] CPU 0 old state 1 new state 2
[    1.836885][   T15] WARNING: CPU: 0 PID: 15 at kernel/rcu/srcutree.c:652 srcu_check_nmi_safety+0x79/0x90
[    1.836897][   T15] Modules linked in:
[    1.836903][   T15] CPU: 0 PID: 15 Comm: pr/bkl Not tainted 6.1.0-rc1+ #9
[    1.836909][   T15] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
[    1.836912][   T15] RIP: 0010:srcu_check_nmi_safety+0x79/0x90
[    1.836919][   T15] Code: d3 80 3d 9f 76 d3 01 00 75 e5 55 8b b0 c8 01 00 00 44 89 c1 48 c7 c7 d0 1f 87 82 c6 05 850
[    1.836923][   T15] RSP: 0000:ffffc90000083e98 EFLAGS: 00010282
[    1.836929][   T15] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[    1.836933][   T15] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000ffffffff
[    1.836936][   T15] RBP: ffffc90000083e98 R08: 0000000000000000 R09: 0000000000000001
[    1.836940][   T15] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
[    1.836943][   T15] R13: ffffc90000013d70 R14: ffff888004073900 R15: 0000000000000000
[    1.836946][   T15] FS:  0000000000000000(0000) GS:ffff888019600000(0000) knlGS:0000000000000000
[    1.836951][   T15] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    1.836954][   T15] CR2: ffff888003c01000 CR3: 0000000002c22001 CR4: 0000000000370ef0
[    1.836962][   T15] Call Trace:
[    1.836964][   T15]  <TASK>
[    1.836970][   T15]  console_bkl_kthread_func+0x27a/0x590
[    1.836981][   T15]  ? _raw_spin_unlock_irqrestore+0x3c/0x60
[    1.836998][   T15]  ? console_fill_outbuf+0x210/0x210
[    1.837003][   T15]  kthread+0x108/0x130
[    1.837012][   T15]  ? kthread_complete_and_exit+0x20/0x20
[    1.837025][   T15]  ret_from_fork+0x1f/0x30
[    1.837059][   T15]  </TASK>
[    1.837062][   T15] irq event stamp: 71
[    1.837065][   T15] hardirqs last  enabled at (73): [<ffffffff81106f99>] vprintk_store+0x1b9/0x5e0
[    1.837070][   T15] hardirqs last disabled at (74): [<ffffffff811071fb>] vprintk_store+0x41b/0x5e0
[    1.837075][   T15] softirqs last  enabled at (0): [<ffffffff8107ce22>] copy_process+0x952/0x1dd0
[    1.837081][   T15] softirqs last disabled at (0): [<0000000000000000>] 0x0
[    1.837085][   T15] ---[ end trace 0000000000000000 ]---
[    1.945054][   T12] Callback from call_rcu_tasks_rude() invoked.

My code is calling srcu_read_lock_nmisafe() from task context, in a
dedicated kthread. I am using DEFINE_STATIC_SRCU() to define/initialize
the srcu struct.

What does the warning imply?

John Ogness

  reply	other threads:[~2022-10-27  9:33 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-21 14:46 [PATCH rcu 0/4] NMI-safe SRCU reader API Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 1/4] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 2/4] srcu: Create and srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 3/4] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-09-21 14:46 ` [PATCH RFC rcu 4/4] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07 ` [PATCH v2 rcu 0/8] NMI-safe SRCU reader API Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 1/8] srcu: Convert ->srcu_lock_count and ->srcu_unlock_count to atomic Paul E. McKenney
2022-09-30 15:02     ` John Ogness
2022-09-30 15:35       ` Paul E. McKenney
2022-09-30 20:37         ` John Ogness
2022-10-01 16:51           ` Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 2/8] srcu: Create an srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() Paul E. McKenney
2022-10-02 15:55     ` Frederic Weisbecker
2022-10-02 15:57       ` Frederic Weisbecker
2022-10-02 16:10         ` Paul E. McKenney
2022-10-02 16:09       ` Paul E. McKenney
2022-10-02 21:47         ` Frederic Weisbecker
2022-10-02 23:46           ` Paul E. McKenney
2022-10-03  9:55             ` Frederic Weisbecker
2022-10-03 11:52               ` Paul E. McKenney
2022-10-18 14:31     ` John Ogness
2022-10-18 15:18       ` Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 3/8] srcu: Check for consistent per-CPU per-srcu_struct NMI safety Paul E. McKenney
2022-10-02 22:06     ` Frederic Weisbecker
2022-10-02 23:51       ` Paul E. McKenney
2022-10-03 10:13         ` Frederic Weisbecker
2022-10-03 11:57           ` Paul E. McKenney
2022-10-03 12:37             ` Frederic Weisbecker
2022-10-03 13:32               ` Paul E. McKenney
2022-10-03 13:36                 ` Frederic Weisbecker
2022-09-29 18:07   ` [PATCH RFC v2 rcu 4/8] srcu: Check for consistent global " Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 5/8] arch/x86: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 6/8] arch/arm64: " Paul E. McKenney
2022-10-05 11:12     ` Mark Rutland
2022-09-29 18:07   ` [PATCH RFC v2 rcu 7/8] arch/loongarch: " Paul E. McKenney
2022-09-29 18:07   ` [PATCH RFC v2 rcu 8/8] arch/s390: " Paul E. McKenney
2022-10-03 14:11   ` [PATCH v2 rcu 0/8] NMI-safe SRCU reader API Frederic Weisbecker
2022-10-03 16:38     ` Paul E. McKenney
2022-10-14 22:47   ` Joel Fernandes
2022-10-14 22:52     ` Joel Fernandes
2022-10-18 10:33   ` John Ogness
2022-10-18 15:24     ` Paul E. McKenney
2022-10-18 18:44       ` John Ogness
2022-10-18 18:59         ` Paul E. McKenney
2022-10-18 21:57           ` Paul E. McKenney
2022-10-19 11:13             ` John Ogness
2022-10-19 19:14               ` Paul E. McKenney
2022-10-19 21:38                 ` John Ogness
2022-10-19 22:05                 ` Frederic Weisbecker
2022-10-20 22:27                   ` Paul E. McKenney
2022-10-20 22:41                     ` Paul E. McKenney
2022-10-21 12:27                     ` John Ogness
2022-10-21 13:59                       ` Paul E. McKenney
2022-10-21 18:41                       ` Paul E. McKenney
2022-10-24  6:15                         ` John Ogness
2022-10-24 13:47                           ` Paul E. McKenney
2022-10-27  9:31                             ` John Ogness [this message]
2022-10-27 14:10                               ` Paul E. McKenney
2022-10-27 14:39                                 ` John Ogness
2022-10-27 16:01                                   ` Paul E. McKenney

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