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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 9EC2DC43381 for ; Tue, 19 Feb 2019 12:38:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7209F2146F for ; Tue, 19 Feb 2019 12:38:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727998AbfBSMiA (ORCPT ); Tue, 19 Feb 2019 07:38:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36436 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725772AbfBSMiA (ORCPT ); Tue, 19 Feb 2019 07:38:00 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B24828667B; Tue, 19 Feb 2019 12:37:59 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.152]) by smtp.corp.redhat.com (Postfix) with SMTP id 1C493610F8; Tue, 19 Feb 2019 12:37:57 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 19 Feb 2019 13:37:59 +0100 (CET) Date: Tue, 19 Feb 2019 13:37:57 +0100 From: Oleg Nesterov To: Guenter Roeck Cc: Andrew Morton , Ben Woodard , "Eric W. Biederman" , Kees Cook , Michal Hocko , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] exec: increase BINPRM_BUF_SIZE to 256 Message-ID: <20190219123756.GA9210@redhat.com> References: <20181112160931.GA28463@redhat.com> <20181112160956.GA28472@redhat.com> <20190218193734.GA29983@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190218193734.GA29983@roeck-us.net> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 19 Feb 2019 12:38:00 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18, Guenter Roeck wrote: > > Unfortunately, this patch causes one of my qemu emulations to crash. > The crash is not always seen, but at least with every other boot attempt. Hmm. I can't imagine how this change can cause the null-ptr-deref in blk_mq_run_hw_queue(). > Reverting the patch fixes the problem. Crash log and bisect results > are attached below. Do you mean that you applied the "revert" patch on top of linux-next ? Or did you rely on git-bisect ? > [ 10.681671] BUG: Kernel NULL pointer dereference at 0x00000040 > [ 10.681826] Faulting instruction address: 0xc0431480 > [ 10.682072] Oops: Kernel access of bad area, sig: 11 [#1] > [ 10.682251] BE PAGE_SIZE=4K PREEMPT Xilinx Virtex440 > [ 10.682387] Modules linked in: > [ 10.682528] CPU: 0 PID: 1 Comm: swapper Tainted: G W 5.0.0-rc6-next-20190218+ #2 > [ 10.682733] NIP: c0431480 LR: c043147c CTR: c0422ad8 > [ 10.682863] REGS: cf82fbe0 TRAP: 0300 Tainted: G W (5.0.0-rc6-next-20190218+) > [ 10.683065] MSR: 00029000 CR: 22000222 XER: 00000000 > [ 10.683236] DEAR: 00000040 ESR: 00000000 > [ 10.683236] GPR00: c043147c cf82fc90 cf82ccc0 00000000 00000000 00000000 00000002 00000000 > [ 10.683236] GPR08: 00000000 00000000 c04310bc 00000000 22000222 00000000 c0002c54 00000000 > [ 10.683236] GPR16: 00000000 00000001 c09aa39c c09021b0 c09021dc 00000007 c0a68c08 00000000 > [ 10.683236] GPR24: 00000001 ced6d400 ced6dcf0 c0815d9c 00000000 00000000 00000000 cedf0800 > [ 10.684331] NIP [c0431480] blk_mq_run_hw_queue+0x28/0x114 > [ 10.684473] LR [c043147c] blk_mq_run_hw_queue+0x24/0x114 > [ 10.684602] Call Trace: > [ 10.684671] [cf82fc90] [c043147c] blk_mq_run_hw_queue+0x24/0x114 (unreliable) > [ 10.684854] [cf82fcc0] [c04315bc] blk_mq_run_hw_queues+0x50/0x7c > [ 10.685002] [cf82fce0] [c0422b24] blk_set_queue_dying+0x30/0x68 > [ 10.685154] [cf82fcf0] [c0423ec0] blk_cleanup_queue+0x34/0x14c > [ 10.685306] [cf82fd10] [c054d73c] ace_probe+0x3dc/0x508 > [ 10.685445] [cf82fd50] [c052d740] platform_drv_probe+0x4c/0xb8 > [ 10.685592] [cf82fd70] [c052abb0] really_probe+0x20c/0x32c > [ 10.685728] [cf82fda0] [c052ae58] driver_probe_device+0x68/0x464 > [ 10.685877] [cf82fdc0] [c052b500] device_driver_attach+0xb4/0xe4 > [ 10.686024] [cf82fde0] [c052b5dc] __driver_attach+0xac/0xfc > [ 10.686161] [cf82fe00] [c0528428] bus_for_each_dev+0x80/0xc0 > [ 10.686314] [cf82fe30] [c0529b3c] bus_add_driver+0x144/0x234 > [ 10.686457] [cf82fe50] [c052c46c] driver_register+0x88/0x15c > [ 10.686610] [cf82fe60] [c09de288] ace_init+0x4c/0xac > [ 10.686742] [cf82fe80] [c0002730] do_one_initcall+0xac/0x330 > [ 10.686888] [cf82fee0] [c09aafd0] kernel_init_freeable+0x34c/0x478 > [ 10.687043] [cf82ff30] [c0002c6c] kernel_init+0x18/0x114 looks unrelated... Oleg.