From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47430) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1drlOd-0002tH-Uc for qemu-devel@nongnu.org; Tue, 12 Sep 2017 09:38:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1drlOZ-0005tk-B6 for qemu-devel@nongnu.org; Tue, 12 Sep 2017 09:38:35 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:2318) by eggs.gnu.org with esmtps (TLS1.0:RSA_ARCFOUR_SHA1:16) (Exim 4.71) (envelope-from ) id 1drlOS-0005hR-SA for qemu-devel@nongnu.org; Tue, 12 Sep 2017 09:38:31 -0400 References: <59B7C252.1070004@huawei.com> From: "WangJie (Captain)" Message-ID: <59B7E305.6080302@huawei.com> Date: Tue, 12 Sep 2017 21:37:09 +0800 MIME-Version: 1.0 In-Reply-To: <59B7C252.1070004@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] =?utf-8?q?question=EF=BC=9A_I_found_a_bug_which_wil?= =?utf-8?q?l_lead_to_qemu_crash?= List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf , eblake@redhat.com Cc: berto@igalia.com, stefanha@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com Hi, Eric I used git-bisect and fount the patch you commited（throttle: Remove block from group on hot-unplug） fixed the bug which I presented to Kevin the patch which fixed the bug is： https://github.com/qemu/qemu/commit/1606e4cf8a976513ecac70ad6642a7ec45744cf5#diff-7cb66df56045598b75a219eebc27efb6 But the condition which I made to causes crash is differ in the condition you described in patch info, is it the same reason? I feel very confused, please tell me, thank you :> On 2017/9/12 19:17, WangJie (Captain) wrote: > Hi, Kevin. > > I found a bug about qemu-kvm(version 2.7.0-rc0 adn 2.8.1). but qemu 2.6.0 and current master is OK. > So I git-bisect the master branch，and I found the patch you commited (block: Decouple throttling from BlockDriverState) lead the bug into qemu. > > The patch which lead the bug into qemu: (https://github.com/qemu/qemu/commit/7ca7f0f6db1fedd28d490795d778cf23979a2aa7#diff-ea36ba0f79150cc299732696a069caba) > > Because the current master is OK. So I think you had fixed it , can you tell me which patch fixed the bug? Thank you :> > > > the bug is that: qemu will crash when loop to attach and detach a disk which configured qos to a VM for a while. > > > *Segmentation fault info(qemu 2.7.0-rc0):* > Using host libthread_db library "/lib64/libthread_db.so.1". > Core was generated by `/usr/bin/qemu-kvm -name guest=wangjie-i-clone203_rhel_7.3_64_guestosdev,debug-t'. > Program terminated with signal 11, Segmentation fault. > #0 0x00007fe960413e3c in throttle_group_next_blk (blk=0x11) at block/throttle-groups.c:160 > 160 ThrottleState *ts = blkp->throttle_state; > Missing separate debuginfos, use: debuginfo-install glib2-2.40.0-4.x86_64 glibc-2.17-157.h5.x86_64 libaio-0.3.109-13.x86_64 libgcc-4.8.3-10.h1.x86_64 nettle-2.7.1-4.h1.x86_64 numactl-libs-2.0.9-4.x86_64 pixman-0.32.4-3.x86_64 zlib-1.2.7-14.x86_64 > (gdb) bt > #0 0x00007fe960413e3c in throttle_group_next_blk (blk=0x11) at block/throttle-groups.c:160 > #1 0x00007fe960413eff in next_throttle_token (blk=0x7fe963f5c400, is_write=false) at block/throttle-groups.c:192 > #2 0x00007fe9604141a8 in throttle_group_co_io_limits_intercept (blk=0x7fe963f5c400, bytes=512, is_write=false) > at block/throttle-groups.c:303 > #3 0x00007fe960400048 in blk_co_preadv (blk=0x7fe963f5c400, offset=0, bytes=512, qiov=0x7ffc37ee8aa0, flags=(unknown: 0)) > at block/block-backend.c:728 > #4 0x00007fe960400159 in blk_read_entry (opaque=0x7ffc37ee8ac0) at block/block-backend.c:769 > #5 0x00007fe96048f4d7 in coroutine_trampoline (i0=1678853408, i1=32745) at util/coroutine-ucontext.c:78 > #6 0x00007fe95dfdacf0 in ?? () from /lib64/libc.so.6 > #7 0x00007ffc37ee9c00 in ?? () > #8 0x0000000000000000 in ?? () > > > > *Segmentation fault info(qemu 2.8.1):* > Program received signal SIGSEGV, Segmentation fault. > 0x00007f5469220607 in blk_has_pending_reqs (blk=0x7f54672a0032, is_write=false) at block/throttle-groups.c:184 > 184 return blkp->pending_reqs[is_write]; > (gdb) bt > #0 0x00007f5469220607 in blk_has_pending_reqs (blk=0x7f54672a0032, is_write=false) at block/throttle-groups.c:184 > #1 0x00007f54692206a8 in next_throttle_token (blk=0x7f546b6cd120, is_write=false) at block/throttle-groups.c:207 > #2 0x00007f5469220984 in throttle_group_co_io_limits_intercept (blk=0x7f546b6cd120, bytes=512, is_write=false) > at block/throttle-groups.c:322 > #3 0x00007f546920bc79 in blk_co_preadv (blk=0x7f546b6cd120, offset=0, bytes=512, qiov=0x7ffcc7355060, flags=0) > at block/block-backend.c:815 > #4 0x00007f546920bddf in blk_read_entry (opaque=0x7ffcc7355080) at block/block-backend.c:865 > #5 0x00007f54692a00f0 in coroutine_trampoline (i0=-588050448, i1=32595) at util/coroutine-ucontext.c:79 > #6 0x00007f5466f34cf0 in ?? () from /lib64/libc.so.6 > #7 0x00007f53f27fa9e0 in ?? () > #8 0x0000000000000000 in ?? () > > > *The way how to find the bug as follows:* > *1、start a VM* > > > *2、attach and detach a disk for a while，the configure of the disk (add-1.xml) as follows* > > > > > > 3000 > 3000 > 120000000 > 120000000 > > > > > *3、run below script for a while，the qemu process of VM will crash* > ret=1 > while [ $ret -ne 0 ]; do > virsh attach-device i-clone203_rhel_7.3_64_guestosdev add-1.xml > sleep 2 > virsh detach-device i-clone203_rhel_7.3_64_guestosdev add-1.xml > done >