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[2604:1380:45d1:ec00::1]) by mx.google.com with ESMTPS id q3-20020a05620a038300b00783f6ed69ccsi8239113qkm.172.2024.01.31.11.28.07 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Jan 2024 11:28:08 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-47016-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=Tgp9VHrN; arc=pass (i=1 dkim=pass dkdomain=kernel.org); spf=pass (google.com: domain of linux-kernel+bounces-47016-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) smtp.mailfrom="linux-kernel+bounces-47016-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ny.mirrors.kernel.org (Postfix) with ESMTPS id D14E71C20F9D for ; Wed, 31 Jan 2024 19:28:07 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id D055E3F8F4; Wed, 31 Jan 2024 19:27:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Tgp9VHrN" 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 1AB993E479; Wed, 31 Jan 2024 19:27:50 +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=1706729271; cv=none; b=c/6w+2pkn7kTwyjhVu6DaEMlNrAifovv4xl0ud6Dgaac8seVStfVsQRBCxbKbOeUXx4NjRwsNuBeoaDuY1fS/9+D5/mtI1juqb0HJUPYXzdUMrNQ5dn8bQFQHruxymSvorXa+Ft8LMedgZXQJ+vJZ+WZAj7WoGz/ITSxhmx0zxk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706729271; c=relaxed/simple; bh=EDuhmI0O4HKI+Hk/K0xvaXTNhoWVCeKb8bazGFeIsrY=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=gEklQJjlivsHoGsC0wMJwLPJa0cXOXqq9PMOPpUIQlh23bp5blouCaR1iFSFMIP7yBAQMZplWL9m68ft04crCqU2xgj1KzPmc6Zq9gAtZaTXKujFsrvvKw4tBvfrkJQozuKWP+y6NE+TV0d1ewz1iZVFpi74+TdW8Qb/dQDTivQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Tgp9VHrN; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A79EC433C7; Wed, 31 Jan 2024 19:27:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706729270; bh=EDuhmI0O4HKI+Hk/K0xvaXTNhoWVCeKb8bazGFeIsrY=; h=Date:From:To:Cc:Subject:From; b=Tgp9VHrN6LKM6GvEZrSPRBC5wxJOsF44BKQXS9XNqEyNVExa/V/sWlaSefi4zgaKF /2EYpLfhhJa55VjDveZo115kYH88qxKQ/99YksNHlBu8x4JMglVMJtcKj9w4zsOexr v88Rw3FofYDLWUdqypvpfTUfW18SHVGDvTLqYZcPL1duhxzAYqjn/CTfT21URs8e+E veGPTUP8ZKoJqMHtuiz5nFyIOmZQFHvDQIjpYQTIAR3LEf/E165f5UMuOvAPy3tXlP uHaa3baCaDVrzlIrl2zzwH0fFYn4jy35LGGBQo4P6VKgIgOhMUfkxQvqihJRx7AITI a08kKj7htY7oA== Date: Wed, 31 Jan 2024 20:27:45 +0100 From: Helge Deller To: Tejun Heo , Lai Jiangshan , linux-kernel@vger.kernel.org Cc: linux-parisc@vger.kernel.org Subject: [PATCH][RFC] workqueue: Fix kernel panic on CPU hot-unplug Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789635369618276168 X-GMAIL-MSGID: 1789635369618276168 When hot-unplugging a 32-bit CPU on the parisc platform with "chcpu -d 1", I get the following kernel panic. Adding a check for !pwq prevents the panic. Kernel Fault: Code=26 (Data memory access rights trap) at addr 00000000 CPU: 1 PID: 21 Comm: cpuhp/1 Not tainted 6.8.0-rc1-32bit+ #1291 Hardware name: 9000/778/B160L IASQ: 00000000 00000000 IAOQ: 10446db4 10446db8 IIR: 0f80109c ISR: 00000000 IOR: 00000000 CPU: 1 CR30: 11dd1710 CR31: 00000000 IAOQ[0]: wq_update_pod+0x98/0x14c IAOQ[1]: wq_update_pod+0x9c/0x14c RP(r2): wq_update_pod+0x80/0x14c Backtrace: [<10448744>] workqueue_offline_cpu+0x1d4/0x1dc [<10429db4>] cpuhp_invoke_callback+0xf8/0x200 [<1042a1d0>] cpuhp_thread_fun+0xb8/0x164 [<10452970>] smpboot_thread_fn+0x284/0x288 [<1044d8f4>] kthread+0x12c/0x13c [<1040201c>] ret_from_kernel_thread+0x1c/0x24 Kernel panic - not syncing: Kernel Fault Signed-off-by: Helge Deller diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 76e60faed892..dfeee7b7322c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -4521,6 +4521,8 @@ static void wq_update_pod(struct workqueue_struct *wq, int cpu, wq_calc_pod_cpumask(target_attrs, cpu, off_cpu); pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu), lockdep_is_held(&wq_pool_mutex)); + if (!pwq) + return; if (wqattrs_equal(target_attrs, pwq->pool->attrs)) return;