[ClusterLabs] Antw: [EXT] Re: Antw: Hanging OCFS2 Filesystem any one else?

[Ulrich Windl]

>>> Gang He <GHe at suse.com> schrieb am 02.06.2021 um 08:34 in Nachricht
<AM6PR04MB6488DE7D2DA906BAD73FA3A1CF3D9 at AM6PR04MB6488.eurprd04.prod.outlook.com>

> Hi Ulrich,
> 
> The hang problem looks like a fix (90bd070aae6c4fb5d302f9c4b9c88be60c8197ec

> ocfs2: fix deadlock between setattr and dio_end_io_write), but it is not
100% 
> sure.
> If possible, could you help to report a bug to SUSE, then we can work on 
> that further.

Hi!

Actually a service request for the issue is open at SUSE. However I don't know
which L3 engineer is working on it.
I have some "funny" effects, like these:
On one node "ls" hangs, but can be interrupted with ^C; on another node "ls"
also hangs, but cannot be stopped with ^C or ^Z
(Most processes cannot even be killed with "kill -9")
"ls" on the directory also hangs, just as an "rm" for a non-existent file

What I really wonder is what triggered the effect, and more importantly  how
to recover from it.
Initially I had suspected a rather full (95%) flesystem, but that means there
are still 24GB available.
The other suspect was concurrent creation of reflink snapshots while the file
being snapshot did change (e.g. allocate a hole in a sparse file)

Regards,
Ulrich

> 
> Thanks
> Gang
> 
> ________________________________________
> From: Users <users‑bounces at clusterlabs.org> on behalf of Ulrich Windl 
> <Ulrich.Windl at rz.uni‑regensburg.de>
> Sent: Tuesday, June 1, 2021 15:14
> To: users at clusterlabs.org 
> Subject: [ClusterLabs] Antw: Hanging OCFS2 Filesystem any one else?
> 
>>>> Ulrich Windl schrieb am 31.05.2021 um 12:11 in Nachricht <60B4B65A.A8F :
161 
> :
> 60728>:
>> Hi!
>>
>> We have an OCFS2 filesystem shared between three cluster nodes (SLES 15
SP2,
>> Kernel 5.3.18‑24.64‑default). The filesystem is filled up to about 95%,
and
>> we have an odd effect:
>> A stat() systemcall to some of the files hangs indefinitely (state "D").
>> ("ls ‑l" and "rm" also hang, but I suspect those are calling state()
>> internally, too).
>> My only suspect is that the effect might be related to the 95% being used.
>> The other suspect is that concurrent reflink calls may trigger the effect.
>>
>> Did anyone else experience something similar?
> 
> Hi!
> 
> I have some details:
> It seems there is a reader/writer deadlock trying to allocate additional 
> blocks for a file.
> The stacktrace looks like this:
> Jun 01 07:56:31 h16 kernel:  rwsem_down_write_slowpath+0x251/0x620
> Jun 01 07:56:31 h16 kernel:  ? __ocfs2_change_file_space+0xb3/0x620 [ocfs2]
> Jun 01 07:56:31 h16 kernel:  __ocfs2_change_file_space+0xb3/0x620 [ocfs2]
> Jun 01 07:56:31 h16 kernel:  ocfs2_fallocate+0x82/0xa0 [ocfs2]
> Jun 01 07:56:31 h16 kernel:  vfs_fallocate+0x13f/0x2a0
> Jun 01 07:56:31 h16 kernel:  ksys_fallocate+0x3c/0x70
> Jun 01 07:56:31 h16 kernel:  __x64_sys_fallocate+0x1a/0x20
> Jun 01 07:56:31 h16 kernel:  do_syscall_64+0x5b/0x1e0
> 
> That is the only writer (on that host), bit there are multiple readers like

> this:
> Jun 01 07:56:31 h16 kernel:  rwsem_down_read_slowpath+0x172/0x300
> Jun 01 07:56:31 h16 kernel:  ? dput+0x2c/0x2f0
> Jun 01 07:56:31 h16 kernel:  ? lookup_slow+0x27/0x50
> Jun 01 07:56:31 h16 kernel:  lookup_slow+0x27/0x50
> Jun 01 07:56:31 h16 kernel:  walk_component+0x1c4/0x300
> Jun 01 07:56:31 h16 kernel:  ? path_init+0x192/0x320
> Jun 01 07:56:31 h16 kernel:  path_lookupat+0x6e/0x210
> Jun 01 07:56:31 h16 kernel:  ? __put_lkb+0x45/0xd0 [dlm]
> Jun 01 07:56:31 h16 kernel:  filename_lookup+0xb6/0x190
> Jun 01 07:56:31 h16 kernel:  ? kmem_cache_alloc+0x3d/0x250
> Jun 01 07:56:31 h16 kernel:  ? getname_flags+0x66/0x1d0
> Jun 01 07:56:31 h16 kernel:  ? vfs_statx+0x73/0xe0
> Jun 01 07:56:31 h16 kernel:  vfs_statx+0x73/0xe0
> Jun 01 07:56:31 h16 kernel:  ? fsnotify_grab_connector+0x46/0x80
> Jun 01 07:56:31 h16 kernel:  __do_sys_newstat+0x39/0x70
> Jun 01 07:56:31 h16 kernel:  ? do_unlinkat+0x92/0x320
> Jun 01 07:56:31 h16 kernel:  do_syscall_64+0x5b/0x1e0
> 
> So that will match the hanging stat() quite nicely!
> 
> However the PID displayed as holding the writer does not exist in the system

> (on that node).
> 
> Regards,
> Ulrich
> 
> 
>>
>> Regards,
>> Ulrich
>>
>>
>>
>>
> 
> 
> 
> 
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