From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13F2AC76188 for ; Fri, 19 Jul 2019 13:53:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D40D921851 for ; Fri, 19 Jul 2019 13:53:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563544434; bh=PWY0uoVGOh2PIWiAEFdra9jU7XP0LdTkL6CqbiecmhI=; h=Date:From:To:Cc:Subject:List-ID:From; b=wCLqyJtg+59Uke7B1PrLsxuQNV52BtNHNIjXfbgPxOLNh1hhcDQVpcTElCiQrujnC oDoXNonvcidpmCBfYhpy23Q5lmAyx3xzovu2vUH2Ts+OZ5A8PQSYoXHxhHbA2/8eWE aczqm4TrfHPf0aIn4LENxkR1X31F8zIHZbVaLY/U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728643AbfGSNxy (ORCPT ); Fri, 19 Jul 2019 09:53:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726239AbfGSNxy (ORCPT ); Fri, 19 Jul 2019 09:53:54 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2373220873; Fri, 19 Jul 2019 13:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1563544433; bh=PWY0uoVGOh2PIWiAEFdra9jU7XP0LdTkL6CqbiecmhI=; h=Date:From:To:Cc:Subject:From; b=JgHCo4v2VcpkMOr8kI0jFODeODS1YOtg9AsqQnJyqBNCHNCTlFh5NFtHqcs1vxwpx qQyCpne+/nfzZ34ku+t1vzhuDvt6A54gDCZrOViO30B6wcPFaTuEiRE7CUfMulmqBA F08wF7Cj2BPP37/60P6QY8I77v78jM+kWN3bJ7gs= Date: Fri, 19 Jul 2019 09:53:52 -0400 From: Sasha Levin To: tglx@linutronix.de, bigeasy@linutronix.de, peterz@infradead.org, mingo@kernel.org, tj@kernel.org, jiangshanlai@gmail.com Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: NULL ptr deref in wq_worker_sleeping on 4.19 Message-ID: <20190719135352.GF4240@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hi folks, We're seeing a rare panic on boot in wq_worker_sleeping() on boot in 4.19 kernels. I wasn't able to reproduce this with 5.2, but I'm not sure whether it's because the issue is fixed, or I was just unlucky. The panic looks like this: [ 0.852791] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 [ 0.853260] PGD 0 P4D 0 [ 0.853260] Oops: 0000 [#1] SMP PTI [ 0.853260] CPU: 7 PID: 49 Comm: Not tainted 4.19.52-9858d02fd940 #1 [ 0.853260] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090007 06/02/2017 [ 0.853260] RIP: 0010:kthread_data+0x12/0x30 [ 0.853260] Code: 83 7f 58 00 74 02 0f 0b e9 bb 2d 19 00 0f 0b eb e2 0f 1f 80 00 00 00 00 0f 1f 44 00 00 f6 47 26 20 74 0c 48 8b 87 98 05 00 00 <48> 8b 40 10 c3 0f 0b 48 8b 87 98 05 00 00 48 8b 40 10 c3 90 66 2e [ 0.853260] RSP: 0000:ffffc900036abe38 EFLAGS: 00010002 [ 0.853260] RAX: 0000000000000000 RBX: ffff8887bfbe17c0 RCX: 0000000000000000 [ 0.853260] RDX: 0000000000000001 RSI: 000000000000000a RDI: ffff8887bbb4bb00 [ 0.853260] RBP: ffffc900036abea0 R08: 0000000000000000 R09: 0000000000000000 [ 0.853260] R10: ffffc9000368bd90 R11: 0000000000000000 R12: ffff8887bbb4bb00 [ 0.853260] R13: 0000000000000000 R14: ffffc900036abe60 R15: 0000000000000000 [ 0.853260] FS: 0000000000000000(0000) GS:ffff8887bfbc0000(0000) knlGS:0000000000000000 [ 0.853260] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.853260] CR2: 0000000000000068 CR3: 00000007df40a000 CR4: 00000000001406e0 [ 0.853260] Call Trace: [ 0.853260] wq_worker_sleeping+0xa/0x60 [ 0.853260] __schedule+0x571/0x8c0 [ 0.853260] schedule+0x32/0x80 [ 0.853260] worker_thread+0xc7/0x440 [ 0.853260] kthread+0xf8/0x130 [ 0.853260] ret_from_fork+0x35/0x40 [ 0.853260] Modules linked in: [ 0.853260] CR2: 0000000000000010 [ 0.853260] ---[ end trace 160fda44361ab977 ]--- I see that this area was recently touched by 6d25be5782e4 ("sched/core, workqueues: Distangle worker accounting from rq lock") but I'm not sure if it's related. -- Thanks, Sasha