Re: smbd blocks for 120 secs and then hangs in D state

[Suresh Jayaraman <sjayaraman@suse.de>]

On 08/28/2010 09:48 AM, Vijai Baskar wrote:
> The server and the client are different.. Server is the board and
> client is my PC.
> 

> 
> On Mon, Aug 23, 2010 at 4:47 PM, Jeff Layton <jlayton@redhat.com> wrote:
>> On Mon, 23 Aug 2010 10:40:34 +0530
>> Vijai Baskar <cristalmaze@gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> I am running a samba copy of a 4GB file from my local hard disk to a
>>> remote hard disk and then find md5sum of the same file in the remote
>>> hard disk through samba read. I do the following to accomplish this:
>>>
>>> 1. mount -t cifs //ip-addr/data /mnt
>>> 2. cp /home/4g /mnt
>>> 3. md5sum /mnt/4g
>>>
>>> After a few iterations of the above operation I get the following
>>> warning on the board:
>>>
>>> echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>> [ 6122.450000] smbd � � � � �D c0204908 � � 0 �9712 � �372 0x00000000
>>> [ 6122.480000] [<c0204908>] (schedule+0x2dc/0x328) from [<c0204980>]
>>> (io_schedule+0x2c/0x48)
>>> [ 6122.500000] [<c0204980>] (io_schedule+0x2c/0x48) from [<c0072064>]
>>> (sync_page+0x44/0x50)
>>> [ 6122.530000] [<c0072064>] (sync_page+0x44/0x50) from [<c0204dd4>]
>>> (__wait_on_bit_lock+0x5c/0xa8)
>>> [ 6122.560000] [<c0204dd4>] (__wait_on_bit_lock+0x5c/0xa8) from
>>> [<c0071ff0>] (__lock_page+0x88/0xa0)
>>> [ 6122.590000] [<c0071ff0>] (__lock_page+0x88/0xa0) from [<c007b530>]
>>> (truncate_inode_pages_range+0x2e4/0x38c)
>>> [ 6122.620000] [<c007b530>] (truncate_inode_pages_range+0x2e4/0x38c)
>>> from [<c007b5f0>] (truncate_inode_pages+0x18/0x20)
>>> [ 6122.640000] [<c007b5f0>] (truncate_inode_pages+0x18/0x20) from
>>> [<c0085acc>] (vmtruncate+0xe4/0x14c)
>>> [ 6122.670000] [<c0085acc>] (vmtruncate+0xe4/0x14c) from [<c00a43a8>]
>>> (inode_setattr+0x48/0x148)
>>> [ 6122.700000] [<c00a43a8>] (inode_setattr+0x48/0x148) from
>>> [<c00a4630>] (notify_change+0x188/0x1dc)
>>> [ 6122.730000] [<c00a4630>] (notify_change+0x188/0x1dc) from
>>> [<c0091440>] (do_truncate+0x6c/0x88)
>>> [ 6122.760000] [<c0091440>] (do_truncate+0x6c/0x88) from [<c00915c0>]
>>> (do_sys_ftruncate+0x164/0x170)
>>> [ 6122.800000] [<c00915c0>] (do_sys_ftruncate+0x164/0x170) from
>>> [<c00915e0>] (sys_ftruncate64+0x14/0x1c)
>>> [ 6122.830000] [<c00915e0>] (sys_ftruncate64+0x14/0x1c) from
>>> [<c0027fa0>] (ret_fast_syscall+0x0/0x2c)
>>>
>>> After this samba daemon hangs in the D state. I changed the values of
>>> /proc/sys/vm/dirty_writeback_centisecs to 250 (default 500) and
>>> /proc/sys/vm/dirty_expire_centisecs to 1000 (default 3000). But this
>>> only delays the problem. ps-ax shows smbd in D state. This problem
>>> seems to occur only during samba read.
>>>
>>> Can someone please provide me a solution for the above problem?
>>>
>>> regards,
>>> vijai
>>>
>>
>> (cc'ing linux-fsdevel and samba-technical as this problem is probably
>> better reported there)
>>
>> The stack trace above is for smbd, so I doubt this has much to do with
>> cifs per-se. Just to make sure though -- are the server and client the
>> same host? Hint: if so, that configuration is prone to deadlock under
>> heavy I/O.
>>
>> When reporting kernel bugs, it's also a good idea to mention the kernel
>> version. It might also be helpful to know what the underlying
>> filesystem is that's being served out.

Care to provide the kernel version and filesystem info requested above?

>>
>> It looks like the process is hung trying to lock a page. Most likely
>> that means that something else is holding that lock and not releasing
>> it for some reason. Debugging this will probably mean figuring out
>> what's holding that lock and why it's not releasing it.
>>

Do you have a reliable way of reproducing the problem?


Thanks,

-- 
Suresh Jayaraman