From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=82.195.75.108 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793376890; b=JCQS60jh85SVxYDpY0GrE0D8WGKMhKCUBwZP/pjWZ/WeMJw6eJfnimsH3qhCgll56Tpk 1s3ot9e/6e8zOT+TPmj5cca4DSm70CHhHbY5eTQF6s8wTjJoXwknmp9NJg3U68eJZ/I/K kll/5Zz8lChqLpeVSkqmKX/xLRWRlk7QWGezV+V7xvIgjV63is3+ELgygTmEWt/uqxx/m rAfzx1xUjVkbt9k0NIDcRZAEr1xuxpCns/EL2nIR1ABWc8x2qsyaRICNVPU6BcA+CRLf0 GezUqSEy0e50Wkm46LYfV8ZKwi5kn2LAKGjrUnHXZB/Uxillx5mb+ZSWr0D7y4Rf9Yw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793376890; h=DMARC-Filter:DKIM-Signature:Received:Date:From:To:Cc:Subject: Message-ID:References:MIME-Version:Content-Type:Content-Disposition: In-Reply-To:X-Debian-User; bh=6VFcCQ8+hkv/Z0Ast47jgNhih51hX02Kw8npjw5+umQ=; b=lDUvvvMUZuX+X/TW1LMDfplhzaBztR51SkzIlpyO3SQhN8J2kQkauw49eBFtzAEdpmJs g+sLFoCDVzrSjXfdyowXL14hy2ub8KFJOv/p0k7zNaKgVsg+ruc9hbncLKX2wyQ0OsQJq kTZ3vKUiPYbt3d8UeScIaSO7nqDnSDDLiy2rrk+3Zpd1w84SSwtkuaxfLnp+6ka9qrWFi +E2Pfe4PxI7ccyZ7ts7QgcNRMF6bW640EJGBHRTR8HKAmKeBG4u9Mbzm7lsd74/vJHi7I jR9uYn7lnn7gsp9nL26F7KhLj8KNMsE/AvzukGdKDB7LXfadKEOdl1MS7RWZMdEv0LA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=debian.org; spf=pass smtp.mailfrom=debian.org; dkim=pass header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=DmPE+J6r; arc=none smtp.remote-ip=82.195.75.108 Received: from stravinsky.debian.org (stravinsky.debian.org [82.195.75.108]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E60C606A31A; Fri, 30 Oct 2026 16:14:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2E60C606A31A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=debian.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=debian.org header.i=@debian.org header.a=rsa-sha256 header.s=smtpauto.stravinsky header.b=DmPE+J6r DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=debian.org; s=smtpauto.stravinsky; h=X-Debian-User:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6VFcCQ8+hkv/Z0Ast47jgNhih51hX02Kw8npjw5+umQ=; b=DmPE+J6rcLlWvdvEniU5xjHTMg H+d/de0QEzHOXUJBPiPynAt/Er7KQmwKTorPs0E8sNua1hxr1/mBuwFqsHvhM4yG/ePe0vDver6E2 0pj2N8OQtUbAt5fzO5DER1IC3Nzcc2Suf+pl6yECGnLl93zJRbnyEmisQW6fQ8AVmM5Ef7bBHOKg7 1rB7PdX0zxqRzcRYRhY0oAawJL0UbspiHi7fVF5Ekqu6sCVjtsIYgm7x0gZnWgKFKSnhVazuJGmdt 0h9S/lzqu7p5F9sfk9eFNolYHXMK6bWwDAKKchRywhK/ontbW2lh9Ojjfzi6ZCjnR5RRfnR/+G3QX jtOMl+Wg==; Received: from authenticated-user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.96) (envelope-from ) id 1xMpFQ-003wWM-2I; Fri, 30 Oct 2026 16:14:33 +0000 Date: Fri, 30 Oct 2026 09:14:27 -0700 From: Breno Leitao To: Stian Halseth Cc: Frederic Weisbecker , Peter Zijlstra , Paul Menzel , Thomas Gleixner , Anna-Maria Behnsen , Ingo Molnar , Shrikanth Hegde , 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 Message-ID: References: <20261025100202.2584654-1-stian@itx.no> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261025100202.2584654-1-stian@itx.no> X-Debian-User: leitao 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: tick_nohz_idle_exit+0x1d5/0x2d0 do_idle+0x3b7/0x4a0 cpu_startup_entry+0x45/0x60 start_secondary+0x1b3/0x200 common_startup_64+0x13e/0x140 irq event stamp: 406130 hardirqs last enabled at (406129): [] cpuidle_enter_state+0x13f/0x465 hardirqs last disabled at (406130): [] tick_nohz_idle_exit+0x62/0x2d0 softirqs last enabled at (406118): [] __irq_exit_rcu+0xc6/0x230 softirqs last disabled at (406111): [] __irq_exit_rcu+0xc6/0x230 ---[ end trace 0000000000000000 ]---