On Wed, Oct 07, 2026 at 03:09:27AM -0400, Mathieu Desnoyers wrote:
> On 2026-10-06 19:40, Paul E. McKenney wrote:
> > Hello!
> >
> > This is all new code, so the bug could be anywhere. So you all need
> > to know. ;-)
> >
> > I got this from the NOPREEMPT variant of hazptr during a nominal
> > "--duration 60" run of torture.sh on x86 with the guest OS split across
> > two NUMA nodes:
> >
> > [ 137.765104] WARNING: kernel/rcu/hazptrtorture.c:658 at
> > hazptr_torture_stats_print+0x25b/0x4f0, CPU#1: hazptr_torture_/136
> > [ 137.768647] Modules linked in:
> > [ 137.768891] CPU: 1 UID: 0 PID: 136 Comm: hazptr_torture_ Not tainted
> > 7.3.0-rc5-00661-ga1f1e4890d1d-dirty #193 PREEMPTLAZY
> > [ 137.769683] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
> > 1.16.3-6.el9 11/05/2023
> > [ 137.770319] RIP: 0010:hazptr_torture_stats_print+0x25b/0x4f0
> > [ 137.770735] Code: 48 83 c4 20 e8 86 44 fe ff 41 83 fd 01 7e 23 48 c7 c6
> > 6e 85 17 b0 48 c7 c7 db 27 17 b0 e8 6d 44 fe ff f0 ff 05 76 6e 0a 02 90
> > <0f> 0b 90 4c 8b 64 24 70 48 c7 c7 73 85 17 b0 e8 51 44 fe ff 48 8b
> > [ 137.772061] RSP: 0018:ffffa738004ffdf0 EFLAGS: 00010202
> > [ 137.772435] RAX: 0000000000000004 RBX: ffffa738004ffe08 RCX:
> > 0000000000000027
> > [ 137.772950] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
> > 0000000000000001
> > [ 137.773455] RBP: ffffa738004ffe60 R08: 4000000000001236 R09:
> > ffffffffb01727df
> > [ 137.773980] R10: 0000000020212121 R11: 0000000020212121 R12:
> > 0000000000000000
> > [ 137.774479] R13: 0000000000000002 R14: 000000000002ffd6 R15:
> > 0000000000034f03
> > [ 137.775000] FS: 0000000000000000(0000) GS:ffff999c2e502000(0000)
> > knlGS:0000000000000000
> > [ 137.775578] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 137.776001] CR2: 0000000000000000 CR3: 0000000008830000 CR4:
> > 00000000000006f0
> > [ 137.776512] Call Trace:
> > [ 137.776700] <TASK>
> > [ 137.776863] ? __pfx_hazptr_torture_stats+0x10/0x10
> > [ 137.777207] hazptr_torture_stats+0x25/0x70
> > [ 137.777508] kthread+0xd9/0x110
> > [ 137.777751] ? __pfx_kthread+0x10/0x10
> > [ 137.778017] ret_from_fork+0x1bd/0x220
> > [ 137.778285] ? __pfx_kthread+0x10/0x10
> > [ 137.778560] ret_from_fork_asm+0x1a/0x30
> > [ 137.778849] </TASK>
> > [ 137.779007] ---[ end trace 0000000000000000 ]---
> >
> > I have not yet seen this during a PREEMPT run. Line 658 of
> > hazptrtorture.c is the WARN_ON_ONCE() below:
> >
> > if (i > 1) {
> > pr_cont("%s", "!!! ");
> > atomic_inc(&n_hazptr_torture_error);
> > WARN_ON_ONCE(i > 1); // Too-short grace period
> > }
> >
> > Any thoughts on what might be causing this?
>
> Hi Paul!
>
> Can you share which tree and branch (commit) this is running ?
>
> Does it include my fix from this series ? That would be patch 1 of:
>
> https://lore.kernel.org/lkml/[email protected]/
Ah, no, I somehow got the impression that this series was going to be
updated, so did not apply it. Apologies!
I will pull these in.
> Does it run the additional series from Kunwu Chan found at
> https://lore.kernel.org/lkml/[email protected]/ ?
No, but if you are good with it I will pull it in.
May I add your Acked-by or Reviewed-by?
Thanx, Paul
> Thanks,
>
> Mathieu
>
> >
> > For that matter, can anyone else reproduce this?
> >
> > Thanx, Paul
>
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> https://www.efficios.com
