From: Breno Leitao <leitao@debian.org>
To: Stian Halseth <stian@itx.no>
Cc: Frederic Weisbecker <frederic@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Paul Menzel <pmenzel@molgen.mpg.de>,
Thomas Gleixner <tglx@kernel.org>,
Anna-Maria Behnsen <anna-maria@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Shrikanth Hegde <sshegde@linux.ibm.com>,
regressions@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/cputime: Don't warn when the tick period starts after idle exit
Date: Fri, 30 Oct 2026 09:14:27 -0700 [thread overview]
Message-ID: <auTCQauaU733PY5z@gmail.com> (raw)
In-Reply-To: <20261025100202.2584654-1-stian@itx.no>
On Sun, Oct 25, 2026 at 11:02:02AM +0100, Stian Halseth wrote:
> I could not hit the window in a KVM guest, but instrumented, the guest
> showed the sched timer armed 5.9 ms after now at HZ=250 right after a
> jiffies -> hpet switch, and tick stops saving a ts->last_tick more than
> a tick ahead. The fix boots without warnings there.
I am seeing this on my testing real hosts:
clocksource: Switched to clocksource tsc-early
------------[ cut here ]------------
WARNING: kernel/sched/cputime.c:481 at kcpustat_dyntick_stop+0x15e/0x1d0, CPU#2: swapper/2/0 [warn]
Modules linked in:
CPU: 2 UID: 0 PID: 0 Comm: swapper/2 Tainted: G S 7.3.0-0_fbk701_debugnightly_rc0_upstream_17997_gc339f4010dea #1 PREEMPTLAZ
Tainted: [S]=CPU_OUT_OF_SPEC
Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A23 12/08/2020
RIP: 0010:kcpustat_dyntick_stop+0x15e/0x1d0
Code: de e8 96 00 00 00 42 0f b6 44 2d 00 84 c0 75 4d 41 c6 07 00 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b e9 2e ff ff ff <0f> 0b eb
RSP: 0000:ffff88828a22fe38 EFLAGS: 00010087
RAX: 0000000b9aef1500 RBX: 0000000b9aeb7036 RCX: 0000000000000001
RDX: 00092e9200000000 RSI: ffffffff851ec9c0 RDI: ffffffff851ccaa0
RBP: 1ffff111c3e65a3b R08: ffffffff8152bd65 R09: 0000000000000001
R10: dffffc0000000000 R11: fffffbfff0f78a9a R12: fffffffffffc5b36
R13: dffffc0000000000 R14: 0000000b9aef1500 R15: ffff888e1f32d1d8
FS: 0000000000000000(0000) GS:ffff888e9684e000(0000) knlGS:0000000000000000
CR2: 0000000000000000 CR3: 000000107162a001 CR4: 00000000007706f0
PKRU: 55555554
Call Trace:
<TASK>
tick_nohz_idle_exit+0x1d5/0x2d0
do_idle+0x3b7/0x4a0
cpu_startup_entry+0x45/0x60
start_secondary+0x1b3/0x200
common_startup_64+0x13e/0x140
</TASK>
irq event stamp: 406130
hardirqs last enabled at (406129): [<ffffffff849e90cf>] cpuidle_enter_state+0x13f/0x465
hardirqs last disabled at (406130): [<ffffffff81557bc2>] tick_nohz_idle_exit+0x62/0x2d0
softirqs last enabled at (406118): [<ffffffff8126dc76>] __irq_exit_rcu+0xc6/0x230
softirqs last disabled at (406111): [<ffffffff8126dc76>] __irq_exit_rcu+0xc6/0x230
---[ end trace 0000000000000000 ]---
next prev parent reply other threads:[~2026-10-30 16:14 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-07 14:29 [PATCH v3] sched/cputime: Don't account idle time twice after dyntick-idle Stian Halseth
2026-10-14 12:17 ` Frederic Weisbecker
2026-10-16 8:01 ` [tip: sched/core] " tip-bot2 for Stian Halseth
2026-10-25 7:27 ` WARNING: kernel/sched/cputime.c:481 at kcpustat_dyntick_stop+0x8b/0xa0, CPU#0: swapper/0/0 (was: [PATCH v3] sched/cputime: Don't account idle time twice after dyntick-idle) Paul Menzel
2026-10-25 8:13 ` Stian Halseth
2026-10-25 10:02 ` [PATCH] sched/cputime: Don't warn when the tick period starts after idle exit Stian Halseth
2026-10-26 16:42 ` Frederic Weisbecker
2026-10-26 17:28 ` Stian Halseth
2026-10-27 17:06 ` Frederic Weisbecker
2026-10-27 19:05 ` Stian Halseth
2026-10-28 14:14 ` Frederic Weisbecker
2026-10-28 17:37 ` Stian Halseth
2026-10-30 16:14 ` Breno Leitao [this message]
2026-10-30 20:48 ` Stian Halseth
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