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* > <disk device="disk" type="file"> > <driver cache="none" io="native" name="qemu" type="raw" /> > <source file="/mnt/sdb/wangjie-kvm/core/fk8b42zr-oz" /> > <target bus="virtio" dev="vdb" /> > <iotune> > <read_iops_sec>3000</read_iops_sec> > <write_iops_sec>3000</write_iops_sec> > <read_bytes_sec>120000000</read_bytes_sec> > <write_bytes_sec>120000000</write_bytes_sec> > </iotune> > </disk> > > > *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 >
