Re: [Qemu-devel] Aborts in iotest 169

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Vladimir Sementsov-Ogievskiy (vsementsov@virtuozzo.com) wrote:
> 24.01.2019 12:29, Vladimir Sementsov-Ogievskiy wrote:
> > 23.01.2019 18:48, Max Reitz wrote:
> >> Hi,
> >>
> >> When running 169 in parallel (e.g. like so:
> >>
> >> $ while TEST_DIR=/tmp/t0 ./check -T -qcow2 169; do; done
> >> $ while TEST_DIR=/tmp/t1 ./check -T -qcow2 169; do; done
> >> $ while TEST_DIR=/tmp/t2 ./check -T -qcow2 169; do; done
> >> $ while TEST_DIR=/tmp/t3 ./check -T -qcow2 169; do; done
> >>
> >> in four different shells), I get aborts:
> >>
> >> (Often I get segfaults, but that's because of
> >> http://lists.nongnu.org/archive/html/qemu-devel/2018-12/msg05579.html --
> >> feel free to apply the attached patch to make them go away)
> >>
> >>
> >> WARNING:qemu:qemu received signal 6:
> >> build/tests/qemu-iotests/../../x86_64-softmmu/qemu-system-x86_64
> >> -chardev socket,id=mon,path=/tmp/t0/tmpbX30XU/qemua-25745-monitor.sock
> >> -mon chardev=mon,mode=control -display none -vga none -qtest
> >> unix:path=/tmp/t0/qemua-25745-qtest.sock -machine accel=qtest
> >> -nodefaults -machine accel=qtest -drive
> >> if=virtio,id=drive0,file=/tmp/t0/disk_a,format=qcow2,cache=writeback
> >> .................E..
> >> ======================================================================
> >> ERROR:
> >> test_do_test_migration_resume_source_not_persistent__not_migbitmap
> >> (__main__.TestDirtyBitmapMigration)
> >> ----------------------------------------------------------------------
> >> Traceback (most recent call last):
> >>    File "169", line 206, in <lambda>
> >>      setattr(klass, 'test_' + method + name, lambda self: mc(self))
> >>    File "169", line 113, in do_test_migration_resume_source
> >>      self.check_bitmap(self.vm_a, sha256)
> >>    File "169", line 72, in check_bitmap
> >>      node='drive0', name='bitmap0')
> >>    File "tests/qemu-iotests/../../scripts/qemu.py", line 369, in qmp
> >>      return self._qmp.cmd(cmd, args=qmp_args)
> >>    File "tests/qemu-iotests/../../scripts/qmp/qmp.py", line 191, in cmd
> >>      return self.cmd_obj(qmp_cmd)
> >>    File "tests/qemu-iotests/../../scripts/qmp/qmp.py", line 174, in cmd_obj
> >>      resp = self.__json_read()
> >>    File "tests/qemu-iotests/../../scripts/qmp/qmp.py", line 82, in
> >> __json_read
> >>      data = self.__sockfile.readline()
> >>    File "/usr/lib64/python2.7/socket.py", line 451, in readline
> >>      data = self._sock.recv(self._rbufsize)
> >> error: [Errno 104] Connection reset by peer
> >>
> >> ----------------------------------------------------------------------
> >> Ran 20 tests
> >>
> >> FAILED (errors=1)
> >>
> >>
> >> Or:
> >>
> >> WARNING:qemu:qemu received signal 6:
> >> build/tests/qemu-iotests/../../x86_64-softmmu/qemu-system-x86_64
> >> -chardev socket,id=mon,path=/tmp/t3/tmp0pllWD/qemua-3445-monitor.sock
> >> -mon chardev=mon,mode=control -display none -vga none -qtest
> >> unix:path=/tmp/t3/qemua-3445-qtest.sock -machine accel=qtest -nodefaults
> >> -machine accel=qtest -drive
> >> if=virtio,id=drive0,file=/tmp/t3/disk_a,format=qcow2,cache=writeback
> >> WARNING:qemu:qemu received signal 6:
> >> build/tests/qemu-iotests/../../x86_64-softmmu/qemu-system-x86_64
> >> -chardev socket,id=mon,path=/tmp/t3/tmp0pllWD/qemua-3445-monitor.sock
> >> -mon chardev=mon,mode=control -display none -vga none -qtest
> >> unix:path=/tmp/t3/qemua-3445-qtest.sock -machine accel=qtest -nodefaults
> >> -machine accel=qtest -drive
> >> if=virtio,id=drive0,file=/tmp/t3/disk_a,format=qcow2,cache=writeback
> >>
> >> ...................F
> >> ======================================================================
> >> FAIL: test_do_test_migration_resume_source_persistent__not_migbitmap
> >> (__main__.TestDirtyBitmapMigration)
> >> ----------------------------------------------------------------------
> >> Traceback (most recent call last):
> >>    File "169", line 206, in <lambda>
> >>      setattr(klass, 'test_' + method + name, lambda self: mc(self))
> >>    File "169", line 125, in do_test_migration_resume_source
> >>      self.assertEqual(log, '')
> >> AssertionError: "qemu-system-x86_64: invalid runstate transition:
> >> 'running' -> 'postmigrate'\n" != ''
> >>
> >> ----------------------------------------------------------------------
> >> Ran 20 tests
> >>
> >> FAILED (failures=1)
> >>
> >>
> >> The backtrace always goes like this:
> >>
> >> (gdb) bt
> >> #0  0x00007f0acf5cc53f in raise () at /lib64/libc.so.6
> >> #1  0x00007f0acf5b6895 in abort () at /lib64/libc.so.6
> >> #2  0x000055a46ebbb1a6 in runstate_set (new_state=RUN_STATE_POSTMIGRATE)
> >> at vl.c:742
> >> #3  0x000055a46ebbb1a6 in runstate_set
> >> (new_state=new_state@entry=RUN_STATE_POSTMIGRATE) at vl.c:730
> >> #4  0x000055a46ed39129 in migration_iteration_finish (s=0x55a4708be000)
> >> at migration/migration.c:2972
> >> #5  0x000055a46ed39129 in migration_thread
> >> (opaque=opaque@entry=0x55a4708be000) at migration/migration.c:3130
> >> #6  0x000055a46eea665a in qemu_thread_start (args=<optimized out>) at
> >> util/qemu-thread-posix.c:502
> >>
> >>
> >> #7  0x00007f0acf76258e in start_thread () at /lib64/libpthread.so.0
> >> #8  0x00007f0acf6916a3 in clone () at /lib64/libc.so.6
> >> (gdb) frame 2
> >> #2  0x000055a46ebbb1a6 in runstate_set (new_state=RUN_STATE_POSTMIGRATE)
> >> at vl.c:742
> >> 742             abort();
> >> (gdb) print current_run_state
> >> $1 = RUN_STATE_RUNNING
> >>
> >>
> >> Neither of migration or runstates are my strong suite, so I thought I'd
> >> report it before diving into it.
> >>
> >> Max
> >>
> > 
> > [...]
> > 450556@1548321072.888979:migrate_set_state new state active
> > 450556@1548321072.889022:migration_thread_setup_complete
> > 450556@1548321072.988275:migrate_transferred transferred 985298 time_spent 100 bandwidth 9852 max_size 2955894
> > 450556@1548321072.988283:migration_bitmap_sync_start
> > 450556@1548321072.988293:migration_bitmap_sync_end dirty_pages 32898
> > 450556@1548321072.988495:migration_thread_low_pending 2048
> > migration_completion
> > 450556@1548321072.988541:runstate_set current_state 9 new_state 7
> > 450556@1548321072.988780:migration_bitmap_sync_start
> > 450556@1548321072.988790:migration_bitmap_sync_end dirty_pages 32898
> > 450556@1548321072.993112:migrate_global_state_pre_save saved state: running
> > [1] 450556@1548321072.993237:migrate_set_state new state completed
> > 450549@1548321072.993668:handle_qmp_command mon 0x55aebef99830 req: {"execute": "x-debug-block-dirty-bitmap-sha256", "arguments": {"name": "bitmap0", "node": "drive0"}}
> > 450556@1548321072.993697:migration_thread_after_loop
> > [2] 450549@1548321072.993917:handle_qmp_command mon 0x55aebef99830 req: {"execute": "cont"}
> > 450476@1548321072.994461:runstate_set current_state 7 new_state 9
> > qemu-system-x86_64: invalid runstate transition: 'running' -> 'postmigrate'
> > 
> > 
> > Aha, so, in test we wait for MIGRATION COMPLETED [1] and run qmp_cont [2] and go to RUNNING.
> > then in migration thread we go to migration_iteration_finish() and fail to go to POSTMIGRATE.
> > (note, that this testcase is about resuming source after migration)
> > 
> > So, fix for test may be additionally wait for POSTMIGRATE, not only for MIGRATION COMPLETION.
> > 
> > But how to fix Qemu not to crash? May be, forbid some transitions (FINISH_MIGRATE -> RUNNING),
> >   or at least error-out qmp_cont if runstate is  FINISH_MIGRATE?
> > 
> > 
> > 
> 
> 
> Ok, this seems to fix test for me:
> 
> diff --git a/tests/qemu-iotests/169 b/tests/qemu-iotests/169
> index 527aebd0cb..dd98168c8d 100755
> --- a/tests/qemu-iotests/169
> +++ b/tests/qemu-iotests/169
> @@ -102,6 +102,10 @@ class TestDirtyBitmapMigration(iotests.QMPTestCase):
>               event = self.vm_a.event_wait('MIGRATION')
>               if event['data']['status'] == 'completed':
>                   break
> +        while True:
> +            result = self.vm_a.qmp('query-status')
> +            if (result['return']['status'] == 'postmigrate'):
> +                break

Hmm; I can see that it might help; although I still can't quite see
how the bad transition that was reported can have happened.

Dave

>           # test that bitmap is still here
>           removed = (not migrate_bitmaps) and persistent
> 
> -
> 
> 
> And this is the full diff of the test I used, to skip checking log (as I enabled traces) and to skip all other test-cases:
> 
> (hmm, we definitely need simple way to run one test case from test, without editing it)
> 
> diff --git a/tests/qemu-iotests/169 b/tests/qemu-iotests/169
> index 527aebd0cb..dd98168c8d 100755
> --- a/tests/qemu-iotests/169
> +++ b/tests/qemu-iotests/169
> @@ -102,6 +102,10 @@ class TestDirtyBitmapMigration(iotests.QMPTestCase):
>               event = self.vm_a.event_wait('MIGRATION')
>               if event['data']['status'] == 'completed':
>                   break
> +        while True:
> +            result = self.vm_a.qmp('query-status')
> +            if (result['return']['status'] == 'postmigrate'):
> +                break
> 
>           # test that bitmap is still here
>           removed = (not migrate_bitmaps) and persistent
> @@ -117,12 +121,12 @@ class TestDirtyBitmapMigration(iotests.QMPTestCase):
> 
>           # catch 'Could not reopen qcow2 layer: Bitmap already exists'
>           # possible error
> -        log = self.vm_a.get_log()
> -        log = re.sub(r'^\[I \d+\.\d+\] OPENED\n', '', log)
> -        log = re.sub(r'^(wrote .* bytes at offset .*\n.*KiB.*ops.*sec.*\n){3}',
> -                     '', log)
> -        log = re.sub(r'\[I \+\d+\.\d+\] CLOSED\n?$', '', log)
> -        self.assertEqual(log, '')
> +        #log = self.vm_a.get_log()
> +        #log = re.sub(r'^\[I \d+\.\d+\] OPENED\n', '', log)
> +        #log = re.sub(r'^(wrote .* bytes at offset .*\n.*KiB.*ops.*sec.*\n){3}',
> +                     #'', log)
> +        #log = re.sub(r'\[I \+\d+\.\d+\] CLOSED\n?$', '', log)
> +        #self.assertEqual(log, '')
> 
>           # test that bitmap is still persistent
>           self.vm_a.launch()
> @@ -211,14 +215,16 @@ for cmb in list(itertools.product((True, False), repeat=4)):
>       name += '_online' if cmb[2] else '_offline'
>       name += '_shared' if cmb[3] else '_nonshared'
> 
> -    inject_test_case(TestDirtyBitmapMigration, name, 'do_test_migration',
> +    if False:
> +        inject_test_case(TestDirtyBitmapMigration, name, 'do_test_migration',
>                        *list(cmb))
> 
>   for cmb in list(itertools.product((True, False), repeat=2)):
>       name = ('_' if cmb[0] else '_not_') + 'persistent_'
>       name += ('_' if cmb[1] else '_not_') + 'migbitmap'
> 
> -    inject_test_case(TestDirtyBitmapMigration, name,
> +    if name == '_persistent__migbitmap':
> +        inject_test_case(TestDirtyBitmapMigration, name,
>                        'do_test_migration_resume_source', *list(cmb))
> 
>   if __name__ == '__main__':
> diff --git a/tests/qemu-iotests/169.out b/tests/qemu-iotests/169.out
> index 3a89159833..ae1213e6f8 100644
> --- a/tests/qemu-iotests/169.out
> +++ b/tests/qemu-iotests/169.out
> @@ -1,5 +1,5 @@
> -....................
> +.
>   ----------------------------------------------------------------------
> -Ran 20 tests
> +Ran 1 tests
> 
>   OK
> 
> 
> 
> -- 
> Best regards,
> Vladimir
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK