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 3128C48AE03 for ; Mon, 18 May 2026 16:13:50 +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=1779120830; cv=none; b=gnXWwk2E7MyoESQxS6ZtvOFdUaSBWmSOPBxxTXlIdaaKj9H4nBAfon0gbDt/OMLcWJqW68Mj93DA0Fy09GndVoEBWexD2VmwKGsz23cXYzaEt45OySoXQ96mZNlB/avxr7qpCkG7Qb3c8OX2q/G6Any4KMIjlq969VEh+je49sY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779120830; c=relaxed/simple; bh=1aPTzS8AxZw6WiwbV8gLyRuVvCej87lMpx6XhMRA5KA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MiAvwNm9mVafsN7xzLlodbx26Q2CzoFGHzREVnWVBUkhLPqlnDaV4GmLEpCZxAgjaVSyZWQEm4EPkJS3Tia6Q63EkfhSCiI2O4nWpZpwBh2IJ4aI2ooHQFFRFKS3nT3CJIH6A2K1i56jCIgEONjHoV+d0GXnwVUmUGynTPBtaGU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O3GQxRXu; 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="O3GQxRXu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E7196C2BCB7; Mon, 18 May 2026 16:13:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1779120829; bh=1aPTzS8AxZw6WiwbV8gLyRuVvCej87lMpx6XhMRA5KA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=O3GQxRXufEXYYUsy8a3Lk4kijg2TASegSHnSLIsWqxYpyCbuPcvISXcwXyJcRoddT G2EfYWpk0g0prJ1IK++pokWCdSEHgYBHA4vk5R19zmgK0/8N6JkV4yqH21FO0Ivef8 Tg4QMx35lmT2UkU5+4LXA9hNzWJN7VQxE/SYvN1gkJ58+/sT0wDNU7VIS0Fk4eVULT 6guoWh5QybDcBC+tqIeS8nik6fDKPLDqaTJW41QBJCJ35E1YpZsIDxomGByy0vzlYO wKpBh0KJkxYZST+n6pn3ViUkuW6J0Lz+DkNzFb4yrjf269Wtyw6Ik5M5FTrlSSWVLT atZpPk0W6H3ig== Received: from phl-compute-01.internal (phl-compute-01.internal [10.202.2.41]) by mailfauth.phl.internal (Postfix) with ESMTP id 42AD9F40089; Mon, 18 May 2026 12:13:48 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-01.internal (MEProxy); Mon, 18 May 2026 12:13:48 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgddufeelfedvucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunheskhgvrhhnvghlrdhorhhgqeenucggtffrrghtthgvrhhnpe elueehtefhtddtgfejvdejueehhfekteevueeuueekgeetieeggeehvdffhefhhfenucff ohhmrghinhepkhgvrhhnvghlrdhorhhgnecuvehluhhsthgvrhfuihiivgeptdenucfrrg hrrghmpehmrghilhhfrhhomhepsghoqhhunhdomhgvshhmthhprghuthhhphgvrhhsohhn rghlihhthidqudeijedtleekgeejuddqudejjeekheehhedvqdgsohhquhhnpeepkhgvrh hnvghlrdhorhhgsehfihigmhgvrdhnrghmvgdpnhgspghrtghpthhtohepudehpdhmohgu vgepshhmthhpohhuthdprhgtphhtthhopehrvghgrhgvshhsihhonhhssehlvggvmhhhuh hishdrihhnfhhopdhrtghpthhtohepphgruhhlmhgtkheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepuhhrvgiikhhisehgmhgrihhlrdgtohhmpdhrtghpthhtohepsghoqhhunh drfhgvnhhgsehgmhgrihhlrdgtohhmpdhrtghpthhtohepjhhovghlrghgnhgvlhhfsehn vhhiughirgdrtghomhdprhgtphhtthhopehrtghusehvghgvrhdrkhgvrhhnvghlrdhorh hgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdho rhhgpdhrtghpthhtohepghhorheslhhinhhugidrihgsmhdrtghomhdprhgtphhtthhope hfrhgvuggvrhhitgeskhgvrhhnvghlrdhorhhg X-ME-Proxy: Feedback-ID: i8dbe485b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 18 May 2026 12:13:47 -0400 (EDT) Date: Mon, 18 May 2026 09:13:46 -0700 From: Boqun Feng To: Thorsten Leemhuis Cc: paulmck@kernel.org, Uladzislau Rezki , Boqun Feng , Joel Fernandes , RCU , LKML , Vasily Gorbik , Frederic Weisbecker , Samir , Shrikanth Hegde , Tejun Heo , Linux kernel regressions list , Jiri Slaby Subject: Re: [PATCH -next v1 05/12] srcu: Don't queue workqueue handlers to never-online CPUs Message-ID: References: <20260511175448.153326-1-urezki@gmail.com> <20260511175448.153326-6-urezki@gmail.com> <3dd5cce0-51f9-4cf1-81b8-246e6c6a633a@paulmck-laptop> <53d546e4-8db0-4e14-a79d-270212081be7@leemhuis.info> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53d546e4-8db0-4e14-a79d-270212081be7@leemhuis.info> On Sun, May 17, 2026 at 09:11:10PM +0200, Thorsten Leemhuis wrote: > On 5/17/26 20:03, Paul E. McKenney wrote: > > On Sun, May 17, 2026 at 02:47:55PM +0200, Uladzislau Rezki wrote: > >> On Wed, May 13, 2026 at 12:38:01PM +0200, Thorsten Leemhuis wrote: > >>> On 5/11/26 19:54, Uladzislau Rezki (Sony) wrote: > >>>> From: "Paul E. McKenney" > >>>> > >>>> While an srcu_struct structure is in the midst of switching from CPU-0 > >>>> to all-CPUs state, it can attempt to invoke callbacks for CPUs that > >>>> have never been online. Worse yet, it can attempt in invoke callbacks > >>>> for CPUs that never will be online, even including imaginary CPUs not in > >>>> cpu_possible_mask. This can cause hangs on s390, > >>> > >>> Uladzislau, Paul, according to the fixes tag below this change fixes a > >>> change that went into 7.0-rc6 -- and apparently causes a "hang" on some > >>> architectures. So shouldn't this be heading to mainline instead of > >>> -next? Ideally with a stable tag to ensure backporting to 7.0.y, but > >>> that is a separate decision? > >>> FWIW, I'm happy to create an urgent PR to Linus with this fix. Since it fixes a commit in the previous urgent fix PR from me. Ulad, let me know if you want me to do it. Regards, Boqun > >> I assume it will be picked to stable > > Thx for the reply. This answered the second aspect I raised. What about > the first: shouldn't this be heading to mainline this cycle, ideally > quite soon? Or is this the plan and I misinterpreted the "-next" in the > subject? > > Sadly Jiri (now CCed) afaics didn't yet report if this fix helped to fix > the issues they were seeing, but it sounded a lot like it was likely: > https://lore.kernel.org/all/f0351414-41af-4f74-899c-87fb5bb45621@kernel.org/ > > >> since there is a "Fixes:" tag. From > >> the other hand i can explicitly update commit message with Cc: stable@vger.kernel.org > >> > >> Paul, any thoughts? > > > > The "Fixes" tag should cover it. > > Often it does, yes, but it might be silently dropped for one reason or > another. So in the end only a stable tag will guarantee backporting > attempt by the stable team. > > Site note: I recently also tried to persuade Greg to also take those > with a stable tag first in case there is a huge backlog. > > Ciao, Thorsten