[Ocfs2-devel] [Question] deadlock on chmod when running discontigous block group multiple node testing

[Eric Ren]

Hi,

When backporting those patches, I find that they are already in our product kernel, maybe
via "stable kernel" policy, although our product kernel is 4.4 while the patches were merged
into 4.6.

Seems it's another deadlock that happens when doing `chmod -R 777 /mnt/ocfs2`
among mutilple nodes at the same time.

Thanks,
Eric
On 10/12/2016 09:23 AM, Eric Ren wrote:
> Hi Junxiao,
>
>> Hi Eric,
>>
>> On 10/11/2016 10:42 AM, Eric Ren wrote:
>>> Hi Junxiao,
>>>
>>> As the subject, the testing hung there on a kernel without your patches:
>>>
>>> "ocfs2: revert using ocfs2_acl_chmod to avoid inode cluster lock hang"
>>> and
>>> "ocfs2: fix posix_acl_create deadlock"
>>>
>>> The stack trace is:
>>> ```
>>> ocfs2cts1:~ # pstree -pl 24133
>>> discontig_runne(24133)───activate_discon(21156)───mpirun(15146)─┬─fillup_contig_b(15149)───sudo(15231)───chmod(15232)
>>>
>>> ocfs2cts1:~ # pgrep -a chmod
>>> 15232 /bin/chmod -R 777 /mnt/ocfs2
>>>
>>> ocfs2cts1:~ # cat /proc/15232/stack
>>> [<ffffffffa05377ef>] __ocfs2_cluster_lock.isra.39+0x1bf/0x620 [ocfs2]
>>> [<ffffffffa053856d>] ocfs2_inode_lock_full_nested+0x12d/0x840 [ocfs2]
>>> [<ffffffffa0538dbb>] ocfs2_inode_lock_atime+0xcb/0x170 [ocfs2]
>>> [<ffffffffa0531e61>] ocfs2_readdir+0x41/0x1b0 [ocfs2]
>>> [<ffffffff8120d03c>] iterate_dir+0x9c/0x110
>>> [<ffffffff8120d453>] SyS_getdents+0x83/0xf0
>>> [<ffffffff815e126e>] entry_SYSCALL_64_fastpath+0x12/0x6d
>>> [<ffffffffffffffff>] 0xffffffffffffffff
>>> ```
>>>
>>> Do you think this issue can be fixed by your patches?
>> Looks not. Those two patches are to fix recursive locking deadlock. But
>> from above call trace, there is no recursive lock.
> Sorry, the call trace on another node was missing.  Here it is:
>
> ocfs2cts2:~ # pstree -lp
> sshd(4292)─┬─sshd(4745)───sshd(4753)───bash(4754)───orted(4781)───fillup_contig_b(4782)───sudo(4864)───chmod(4865)
>
> ocfs2cts2:~ # cat /proc/4865/stack
> [<ffffffffa053e7ef>] __ocfs2_cluster_lock.isra.39+0x1bf/0x620 [ocfs2]
> [<ffffffffa053f56d>] ocfs2_inode_lock_full_nested+0x12d/0x840 [ocfs2]
> [<ffffffffa059c860>] ocfs2_iop_get_acl+0x40/0xf0 [ocfs2]
> [<ffffffff812044e6>] generic_permission+0x166/0x1c0
> [<ffffffffa0542aca>] ocfs2_permission+0xaa/0xd0 [ocfs2]
> [<ffffffff81204596>] __inode_permission+0x56/0xb0
> [<ffffffff812068fa>] link_path_walk+0x29a/0x560
> [<ffffffff81206cbf>] path_lookupat+0x7f/0x110
> [<ffffffff8120929c>] filename_lookup+0x9c/0x150
> [<ffffffff811f96c3>] SyS_fchmodat+0x33/0x90
> [<ffffffff815e126e>] entry_SYSCALL_64_fastpath+0x12/0x6d
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Thanks,
> Eric
>
>
>> Thanks,
>> Junxiao.
>>> I will try your patches later, but I am little worried the possibility
>>> of reproduction may not be 100%.
>>> So ask you to confirm;-)
>>>
>>> Eric
>
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