On 9/11/19 4:33 PM, Eric Blake wrote: > I tried to test this patch, but even with it applied, I still got an > aio-context crasher by attempting an nbd-server-start, nbd-server-add, > nbd-server-stop (intentionally skipping the nbd-server-remove step) on a > domain using iothreads, with a backtrace of:
The crash also reproduces with nbd-server-remove instead of nbd-server-stop. Both QMP commands eventually call into the blk_remove_bs() that calls the fatal blk_drain(). So libvirt can't work around the bug merely by adding an nbd-server-remove step. > > #0 0x00007ff09d070e35 in raise () from target:/lib64/libc.so.6 > #1 0x00007ff09d05b895 in abort () from target:/lib64/libc.so.6 > #2 0x000055dd03b9ab86 in error_exit (err=1, msg=0x55dd03d59fb0 > <__func__.15769> "qemu_mutex_unlock_impl") > at util/qemu-thread-posix.c:36 > #3 0x000055dd03b9adcf in qemu_mutex_unlock_impl (mutex=0x55dd062d5090, > file=0x55dd03d59041 "util/async.c", > line=523) at util/qemu-thread-posix.c:96 > #4 0x000055dd03b93433 in aio_context_release (ctx=0x55dd062d5030) at > util/async.c:523 > #5 0x000055dd03ac421b in bdrv_do_drained_begin (bs=0x55dd0673a2d0, > recursive=false, parent=0x0, > ignore_bds_parents=false, poll=true) at block/io.c:428 > #6 0x000055dd03ac4299 in bdrv_drained_begin (bs=0x55dd0673a2d0) at > block/io.c:434 > #7 0x000055dd03aafb54 in blk_drain (blk=0x55dd06a3ec40) at > block/block-backend.c:1605 > #8 0x000055dd03aae054 in blk_remove_bs (blk=0x55dd06a3ec40) at > block/block-backend.c:800 -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
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