8.1-STABLE: problem with unmounting ZFS snapshots
mm at FreeBSD.org
Sat Nov 13 02:27:12 UTC 2010
Yes, this is indeed a leak introduced by importing onnv revision 9214
and it exists in perforce as well - very easy to reproduce.
# mount -t zfs test at t1 /mnt
# umount /mnt (-> hang)
This is not compatible with mounting snapshots outside mounted ZFS and I
was not able to reproduce the errors defined in 6604992 and 6810367
(they are Solaris-specific). I suggest we comment out this code (from
head, later MFC and p4 as well).
Patch (should work with HEAD and 8-STABLE):
Dňa 12.11.2010 15:27, Andriy Gapon wrote / napísal(a):
> on 12/11/2010 16:00 Alexander Zagrebin said the following:
>> Thanks for your reply!
>>>> 2. the umount is waiting for disk
>>>> #ps | egrep 'PID|umount'
>>>> PID TT STAT TIME COMMAND
>>>> 958 0 D+ 0:00,04 umount /mnt
>>>> # procstat -t 958
>>>> PID TID COMM TDNAME CPU PRI
>>> STATE WCHAN
>>>> 958 100731 umount - 3 133
>>> sleep mntref
>>> procstat -kk <pid>
>> $ ps a | grep umount
>> 86874 2- D 0:00,06 umount /mnt
>> 90433 3 S+ 0:00,01 grep umount
>> $ sudo procstat -kk 86874
>> PID TID COMM TDNAME KSTACK
>> 86874 100731 umount - mi_switch+0x176
>> sleepq_wait+0x42 _sleep+0x317 vfs_mount_destroy+0x5a dounmount+0x4d4
>> unmount+0x38b syscall+0x1cf Xfast_syscall+0xe2
> Looks like possible mnt_ref leak.
> I think that something like that was fixed some not long time ago.
> Perhaps you either don't have the fix or there is another leak.
> What revision do you have?
> Perhaps Martin has an insight here.
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