The following steps will cause qemu assertion failure:
- pause vm by executing 'virsh suspend'
- create external snapshot of memory and disk using 'virsh snapshot-create-as'
- doing the above operation again will cause qemu crash
The backtrace looks like:
#0 0x00007fbf958c5c37 in raise () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007fbf958c9028 in abort () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x00007fbf958bebf6 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3 0x00007fbf958beca2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
#4 0x000055ca8decd39d in bdrv_inactivate_recurse (bs=0x55ca90c80400) at
/build/qemu-5.0/block.c:5724
#5 0x000055ca8dece967 in bdrv_inactivate_all () at
/build//qemu-5.0/block.c:5792
#6 0x000055ca8de5539d in qemu_savevm_state_complete_precopy_non_iterable
(inactivate_disks=true, in_postcopy=false, f=0x55ca907044b0)
at /build/qemu-5.0/migration/savevm.c:1401
#7 qemu_savevm_state_complete_precopy (f=0x55ca907044b0,
iterable_only=iterable_only@entry=false,
inactivate_disks=inactivate_disks@entry=true)
at /build/qemu-5.0/migration/savevm.c:1453
#8 0x000055ca8de4f581 in migration_completion (s=0x55ca8f64d9f0) at
/build/qemu-5.0/migration/migration.c:2941
#9 migration_iteration_run (s=0x55ca8f64d9f0) at
/build/qemu-5.0/migration/migration.c:3295
#10 migration_thread (opaque=opaque@entry=0x55ca8f64d9f0) at
/build/qemu-5.0/migration/migration.c:3459
#11 0x000055ca8dfc6716 in qemu_thread_start (args=<optimized out>) at
/build/qemu-5.0/util/qemu-thread-posix.c:519
#12 0x00007fbf95c5f184 in start_thread () from
/lib/x86_64-linux-gnu/libpthread.so.0
#13 0x00007fbf9598cbed in clone () from /lib/x86_64-linux-gnu/libc.so.6
When the first migration completes, bs->open_flags will set BDRV_O_INACTIVE
flag by bdrv_inactivate_all(), and during the second migration the
bdrv_inactivate_recurse assert that the bs->open_flags is already
BDRV_O_INACTIVE enabled which cause crash.
As Vladimir suggested, this patch makes migrate_prepare check the state of vm
and
return error if it is in RUN_STATE_POSTMIGRATE state.
Signed-off-by: Tuguoyi<tu.guoyi@h3c.com>