From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D4E02236E3 for ; Mon, 11 May 2026 05:21:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778476893; cv=none; b=P0xQQARGcy6v+dPAQh9YkxghinuVzqNMARane0x5Vfi+Ouciy2ofhRWkIWA9QWqnYVKFSBFA0x7avvpnoaCURMVkwsu/9IHhqDpbWBTUZSxPS35G9YXvYg2AZ8z+hBQ02hhtogokdvcZGgvaruKme2VmfloPsigID6HSQIwdzJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778476893; c=relaxed/simple; bh=BQsHiHWAddULiL/h2opbrrEfePQRiDl4Unc2OrlIgxo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eRORgUMPAr91KjjXwJSJV77E2Vch1+M3Gloeu6UEp9tRY92ICQiC42Ty6qama7fFjdyfQgFFGQOvDHvzDB4bIrDlXborj2lZP17MUMFf7yB1Vr8L7hxPmETnsJYYQQcapcl585838TPhaalNaf8QKoLmUMAdcmmq3eaV+SsEBuI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Q+/lRezC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Q+/lRezC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B397C2BCB0; Mon, 11 May 2026 05:21:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778476892; bh=BQsHiHWAddULiL/h2opbrrEfePQRiDl4Unc2OrlIgxo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Q+/lRezCvXqi3nFrpNWWMFrxrofzdjY/hYtgTEzZpbSibRxQ9IeLGnYK6Zt/IqP+p nzD3p9A/PD3AUyG4aQiB91wFUp0yNOiAxD12jLkALr+DOk7D+1plUiinsHh6NqsdCi OwPlM9gA/S8lmeL2TA0BzP3Q15YRD4A/7B6NJOliJPE/oRf7xPhGJei1uO+BVAp60f IH2WAluqPvAx69RhWdIDxSRj+k2WeATiBMKFQ0LFfQjXukIbxcDJ0AhQ2piFLgEIKS P5YIJcn+SEmdwnpbfRC6K8i02jFMMVp0zBLdYR9h2AoKBQ7rArjc5IgjQa1ah2H5jf gOvNHs7W5J8Sg== Message-ID: <671a7905-f6b3-4bd4-bb08-130a5cc340e4@kernel.org> Date: Mon, 11 May 2026 07:21:28 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/5] workqueue: Show all busy workers in stall diagnostics To: Breno Leitao Cc: Tejun Heo , Lai Jiangshan , Andrew Morton , linux-kernel@vger.kernel.org, Omar Sandoval , Song Liu , Danielle Costantino , kasan-dev@googlegroups.com, Petr Mladek , kernel-team@meta.com References: <20260305-wqstall_start-at-v2-0-b60863ee0899@debian.org> <20260305-wqstall_start-at-v2-4-b60863ee0899@debian.org> <4ed2b000-2306-49fe-87b8-8bfd7f6b6d43@kernel.org> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, we currently have several reports of this. On s390, ppc64, and x86_64. On 07. 05. 26, 15:11, Breno Leitao wrote: > Hi Jiri, > > On Thu, May 07, 2026 at 12:20:33PM +0200, Jiri Slaby wrote: >> On 05. 03. 26, 17:15, Breno Leitao wrote: >> >> BUG: workqueue lockup - pool cpus=144 node=0 flags=0x4 nice=0 stuck for >> 168224s! > > That's an extremely long stall (~1.95 days). > >> ... >> Showing busy workqueues and worker pools: >> workqueue rcu_gp: flags=0x108 >> pwq 578: cpus=144 node=0 flags=0x4 nice=0 active=3 refcnt=4 >> in: >> https://bugzilla.suse.com/show_bug.cgi?id=1263947 >> ? >> >> Can this (or other patch from the series) cause this? Should there be >> something like cpu_online() instead of task_is_running() somewhere? > > This series only affects stall reporting, not detection. The changes run > after the watchdog has identified a stall, so the detection logic itself > remains unchanged. > > To help diagnose this issue, could you provide some additional information: > > 1) Was CPU 144 online at any point? If so, when was it taken offline? It was not, it's non-present. > 2) Does this message appear repeatedly? If you bring CPU 144 online, does > the issue resolve? Yes, look at this new x86_64 report's dmesg (I believe it is related to the above report): BUG: workqueue lockup - pool cpus=2 node=0 flags=0x4 nice=0 stuck for 50s! in: https://bugzilla.suse.com/attachment.cgi?id=890229 $ grep -c BUG sl.txt 504 $ grep -c pwq sl.txt 509 It comes from: https://bugzilla.suse.com/show_bug.cgi?id=1264554 > 3) Have you run similar tests on earlier kernel versions without seeing > this behavior, or is this a clear regression? It's new in 7.0. Going back to 6.19.12 makes it disappear. thanks, -- js suse labs