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McKenney wrote: > 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] >>> [ 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] >>> [ 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/20260927155134.4740-1-mathieu.desnoyers@efficios.com/ > > 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. About the patches introducing ptr_eq(), I plan to handle Linus' feedback perhaps in an additional patch and have the "generic" ptr_eq() implemented under asm-generic, and a x86-specific implementation of it in assembly. Are you OK with this being a follow up or would you prefer I fold this in the original patch ? > >> Does it run the additional series from Kunwu Chan found at >> https://lore.kernel.org/lkml/20261002170847.3653663-1-kunwu.chan@gmail.com/ ? > > No, but if you are good with it I will pull it in. > > May I add your Acked-by or Reviewed-by? With LPC going on, I did not have time to review it, sorry. Not yet please. Thanks, Mathieu > > Thanx, Paul > >> Thanks, >> >> Mathieu >> >>> >>> For that matter, can anyone else reproduce this? >>> >>> Thanx, Paul >> >> >> -- >> Mathieu Desnoyers >> EfficiOS Inc. >> https://www.efficios.com -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com