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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 8FDF6C33C99 for ; Wed, 8 Jan 2020 01:55:53 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5D33D20678 for ; Wed, 8 Jan 2020 01:55:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D33D20678 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:58910 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip0Zc-0006jr-FM for qemu-devel@archiver.kernel.org; Tue, 07 Jan 2020 20:55:52 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33416) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ip0Yz-00063X-TK for qemu-devel@nongnu.org; Tue, 07 Jan 2020 20:55:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ip0Yr-00083u-Rc for qemu-devel@nongnu.org; Tue, 07 Jan 2020 20:55:07 -0500 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:16112) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ip0Yr-00080Y-Gz for qemu-devel@nongnu.org; Tue, 07 Jan 2020 20:55:05 -0500 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R161e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e07486; MF=eguan@linux.alibaba.com; NM=1; PH=DS; RN=4; SR=0; TI=SMTPD_---0Tn7WaD1_1578448483; Received: from localhost(mailfrom:eguan@linux.alibaba.com fp:SMTPD_---0Tn7WaD1_1578448483) by smtp.aliyun-inc.com(127.0.0.1); Wed, 08 Jan 2020 09:54:44 +0800 Date: Wed, 8 Jan 2020 09:54:43 +0800 From: Eryu Guan To: Julia Suvorova Subject: Re: [BUG qemu 4.0] segfault when unplugging virtio-blk-pci device Message-ID: <20200108015443.GI41863@e18g06458.et15sqa> References: <20191231103434.GA41863@e18g06458.et15sqa> <20191231115136.7b967604@Igors-MacBook-Pro> <20200102020850.GB41863@e18g06458.et15sqa> <20200107130649.GH41863@e18g06458.et15sqa> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 47.88.44.36 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Igor Mammedov , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, Jan 07, 2020 at 03:01:01PM +0100, Julia Suvorova wrote: > On Tue, Jan 7, 2020 at 2:06 PM Eryu Guan wrote: > > > > On Thu, Jan 02, 2020 at 10:08:50AM +0800, Eryu Guan wrote: > > > On Tue, Dec 31, 2019 at 11:51:35AM +0100, Igor Mammedov wrote: > > > > On Tue, 31 Dec 2019 18:34:34 +0800 > > > > Eryu Guan wrote: > > > > > > > > > Hi, > > > > > > > > > > I'm using qemu 4.0 and hit segfault when tearing down kata sandbox, I > > > > > think it's because io completion hits use-after-free when device is > > > > > already gone. Is this a known bug that has been fixed? (I went through > > > > > the git log but didn't find anything obvious). > > > > > > > > > > gdb backtrace is: > > > > > > > > > > Core was generated by `/usr/local/libexec/qemu-kvm -name sandbox-5b8df8c6c6901c3c0a9b02879be10fe8d69d6'. > > > > > Program terminated with signal 11, Segmentation fault. > > > > > #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903 > > > > > 903 return obj->class; > > > > > (gdb) bt > > > > > #0 object_get_class (obj=obj@entry=0x0) at /usr/src/debug/qemu-4.0/qom/object.c:903 > > > > > #1 0x0000558a2c009e9b in virtio_notify_vector (vdev=0x558a2e7751d0, > > > > > vector=) at /usr/src/debug/qemu-4.0/hw/virtio/virtio.c:1118 > > > > > #2 0x0000558a2bfdcb1e in virtio_blk_discard_write_zeroes_complete ( > > > > > opaque=0x558a2f2fd420, ret=0) > > > > > at /usr/src/debug/qemu-4.0/hw/block/virtio-blk.c:186 > > > > > #3 0x0000558a2c261c7e in blk_aio_complete (acb=0x558a2eed7420) > > > > > at /usr/src/debug/qemu-4.0/block/block-backend.c:1305 > > > > > #4 0x0000558a2c3031db in coroutine_trampoline (i0=, > > > > > i1=) at /usr/src/debug/qemu-4.0/util/coroutine-ucontext.c:116 > > > > > #5 0x00007f45b2f8b080 in ?? () from /lib64/libc.so.6 > > > > > #6 0x00007fff9ed75780 in ?? () > > > > > #7 0x0000000000000000 in ?? () > > > > > > > > > > It seems like qemu was completing a discard/write_zero request, but > > > > > parent BusState was already freed & set to NULL. > > > > > > > > > > Do we need to drain all pending request before unrealizing virtio-blk > > > > > device? Like the following patch proposed? > > > > > > > > > > https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg02945.html > > > > > > > > > > If more info is needed, please let me know. > > > > > > > > may be this will help: https://patchwork.kernel.org/patch/11213047/ > > > > > > Yeah, this looks promising! I'll try it out (though it's a one-time > > > crash for me). Thanks! > > > > After applying this patch, I don't see the original segfaut and > > backtrace, but I see this crash > > > > [Thread debugging using libthread_db enabled] > > Using host libthread_db library "/lib64/libthread_db.so.1". > > Core was generated by `/usr/local/libexec/qemu-kvm -name sandbox-a2f34a11a7e1449496503bbc4050ae040c0d3'. > > Program terminated with signal 11, Segmentation fault. > > #0 0x0000561216a57609 in virtio_pci_notify_write (opaque=0x5612184747e0, addr=0, val=, size=) at /usr/src/debug/qemu-4.0/hw/virtio/virtio-pci.c:1324 > > 1324 VirtIOPCIProxy *proxy = VIRTIO_PCI(DEVICE(vdev)->parent_bus->parent); > > Missing separate debuginfos, use: debuginfo-install glib2-2.42.2-5.1.alios7.x86_64 glibc-2.17-260.alios7.x86_64 libgcc-4.8.5-28.alios7.1.x86_64 libseccomp-2.3.1-3.alios7.x86_64 libstdc++-4.8.5-28.alios7.1.x86_64 numactl-libs-2.0.9-5.1.alios7.x86_64 pixman-0.32.6-3.1.alios7.x86_64 zlib-1.2.7-16.2.alios7.x86_64 > > (gdb) bt > > #0 0x0000561216a57609 in virtio_pci_notify_write (opaque=0x5612184747e0, addr=0, val=, size=) at /usr/src/debug/qemu-4.0/hw/virtio/virtio-pci.c:1324 > > #1 0x0000561216835b22 in memory_region_write_accessor (mr=, addr=, value=, size=, shift=, mask=, attrs=...) at /usr/src/debug/qemu-4.0/memory.c:502 > > #2 0x0000561216833c5d in access_with_adjusted_size (addr=addr@entry=0, value=value@entry=0x7fcdeab1b8a8, size=size@entry=2, access_size_min=, access_size_max=, access_fn=0x561216835ac0 , mr=0x56121846d340, attrs=...) > > at /usr/src/debug/qemu-4.0/memory.c:568 > > #3 0x0000561216837c66 in memory_region_dispatch_write (mr=mr@entry=0x56121846d340, addr=0, data=, size=2, attrs=attrs@entry=...) at /usr/src/debug/qemu-4.0/memory.c:1503 > > #4 0x00005612167e036f in flatview_write_continue (fv=fv@entry=0x56121852edd0, addr=addr@entry=841813602304, attrs=..., buf=buf@entry=0x7fce7dd97028
, len=len@entry=2, addr1=, l=, mr=0x56121846d340) > > at /usr/src/debug/qemu-4.0/exec.c:3279 > > #5 0x00005612167e0506 in flatview_write (fv=0x56121852edd0, addr=841813602304, attrs=..., buf=0x7fce7dd97028
, len=2) at /usr/src/debug/qemu-4.0/exec.c:3318 > > #6 0x00005612167e4a1b in address_space_write (as=, addr=, attrs=..., buf=, len=) at /usr/src/debug/qemu-4.0/exec.c:3408 > > #7 0x00005612167e4aa5 in address_space_rw (as=, addr=, attrs=..., attrs@entry=..., buf=buf@entry=0x7fce7dd97028
, len=, is_write=) at /usr/src/debug/qemu-4.0/exec.c:3419 > > #8 0x0000561216849da1 in kvm_cpu_exec (cpu=cpu@entry=0x56121849aa00) at /usr/src/debug/qemu-4.0/accel/kvm/kvm-all.c:2034 > > #9 0x000056121682255e in qemu_kvm_cpu_thread_fn (arg=arg@entry=0x56121849aa00) at /usr/src/debug/qemu-4.0/cpus.c:1281 > > #10 0x0000561216b794d6 in qemu_thread_start (args=) at /usr/src/debug/qemu-4.0/util/qemu-thread-posix.c:502 > > #11 0x00007fce7bef6e25 in start_thread () from /lib64/libpthread.so.0 > > #12 0x00007fce7bc1ef1d in clone () from /lib64/libc.so.6 > > > > And I searched and found > > https://bugzilla.redhat.com/show_bug.cgi?id=1706759 , which has the same > > backtrace as above, and it seems commit 7bfde688fb1b ("virtio-blk: Add > > blk_drain() to virtio_blk_device_unrealize()") is to fix this particular > > bug. > > > > But I can still hit the bug even after applying the commit. Do I miss > > anything? > > Hi Eryu, > This backtrace seems to be caused by this bug (there were two bugs in > 1706759): https://bugzilla.redhat.com/show_bug.cgi?id=1708480 > Although the solution hasn't been tested on virtio-blk yet, you may > want to apply this patch: > https://lists.nongnu.org/archive/html/qemu-devel/2019-12/msg05197.html > Let me know if this works. Will try it out, thanks a lot! Eryu