38-rc1: umount+rmmod cause ext4 error.

38-rc1: umount+rmmod cause ext4 error.

[Tao Ma]

Hi Nick and Ted,
	I ran some very basic test with 38-rc1 and my box run into error with 
the message like:

slab error in kmem_cache_destroy(): cache `ext4_inode_cache': Can't free 
all objects
Pid: 4395, comm: rmmod Not tainted 2.6.38-rc1 #1
Call Trace:
  [<ffffffff820d61dc>] ? kmem_cache_destroy+0x83/0xc7
  [<ffffffffa0574025>] ? destroy_inodecache+0x15/0x17 [ext4]
  [<ffffffffa05923d1>] ? ext4_exit_fs+0x109/0x143 [ext4]
  [<ffffffff8203d194>] ? put_online_cpus+0x56/0x58
  [<ffffffff8206735a>] ? module_refcount+0x85/0x9d
  [<ffffffff82067b22>] ? sys_delete_module+0x1b5/0x218
  [<ffffffff82074fc3>] ? audit_syscall_entry+0x187/0x1ba
  [<ffffffff82002a6b>] ? system_call_fastpath+0x16/0x1b
SLAB: cache with size 888 has lost its name
SLAB: cache with size 888 has lost its name
SLAB: cache with size 888 has lost its name
SLAB: cache with size 888 has lost its name

The reproduce process is simple:just rmmod ext4 immediately after umount 
an ext4 volume.

I have done some very simple investigation and it seems that with Nick's 
new ext4_i_callback, even after we do ext4_destroy_inode, it isn't 
freed. So after we destroy the ext_inode_cache, and when freeing the 
inode, it errors. Hope it helps. If you have any fixes, I can test it.

Regards,
Tao

Re: 38-rc1: umount+rmmod cause ext4 error.

[Maciej Rutecki]

I created a Bugzilla entry at 
https://bugzilla.kernel.org/show_bug.cgi?id=27652
for your bug report, please add your address to the CC list in there, thanks!

On środa, 19 stycznia 2011 o 07:53:36 Tao Ma wrote:
> Hi Nick and Ted,
> 	I ran some very basic test with 38-rc1 and my box run into error with
> the message like:
> 
> slab error in kmem_cache_destroy(): cache `ext4_inode_cache': Can't free
> all objects
> Pid: 4395, comm: rmmod Not tainted 2.6.38-rc1 #1
> Call Trace:
>   [<ffffffff820d61dc>] ? kmem_cache_destroy+0x83/0xc7
>   [<ffffffffa0574025>] ? destroy_inodecache+0x15/0x17 [ext4]
>   [<ffffffffa05923d1>] ? ext4_exit_fs+0x109/0x143 [ext4]
>   [<ffffffff8203d194>] ? put_online_cpus+0x56/0x58
>   [<ffffffff8206735a>] ? module_refcount+0x85/0x9d
>   [<ffffffff82067b22>] ? sys_delete_module+0x1b5/0x218
>   [<ffffffff82074fc3>] ? audit_syscall_entry+0x187/0x1ba
>   [<ffffffff82002a6b>] ? system_call_fastpath+0x16/0x1b
> SLAB: cache with size 888 has lost its name
> SLAB: cache with size 888 has lost its name
> SLAB: cache with size 888 has lost its name
> SLAB: cache with size 888 has lost its name
> 
> The reproduce process is simple:just rmmod ext4 immediately after umount
> an ext4 volume.
> 
> I have done some very simple investigation and it seems that with Nick's
> new ext4_i_callback, even after we do ext4_destroy_inode, it isn't
> freed. So after we destroy the ext_inode_cache, and when freeing the
> inode, it errors. Hope it helps. If you have any fixes, I can test it.
> 
> Regards,
> Tao
> --
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-- 
Maciej Rutecki
http://www.maciek.unixy.pl
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Re: 38-rc1: umount+rmmod cause ext4 error.

[Eric Sandeen]

On 1/26/11 2:28 PM, Maciej Rutecki wrote:
> I created a Bugzilla entry at 
> https://bugzilla.kernel.org/show_bug.cgi?id=27652
> for your bug report, please add your address to the CC list in there, thanks!

I believe patches have been sent that should fix this; there were
2 module unloading regressions in .37, both fixed.

If you can test with:

http://marc.info/?l=linux-ext4&m=129546975702198&w=2
and
http://marc.info/?l=linux-ext4&m=129527644524410&w=2

that'd be great.

Thanks,
-Eric

> On środa, 19 stycznia 2011 o 07:53:36 Tao Ma wrote:
>> Hi Nick and Ted,
>> 	I ran some very basic test with 38-rc1 and my box run into error with
>> the message like:
>>
>> slab error in kmem_cache_destroy(): cache `ext4_inode_cache': Can't free
>> all objects
>> Pid: 4395, comm: rmmod Not tainted 2.6.38-rc1 #1
>> Call Trace:
>>   [<ffffffff820d61dc>] ? kmem_cache_destroy+0x83/0xc7
>>   [<ffffffffa0574025>] ? destroy_inodecache+0x15/0x17 [ext4]
>>   [<ffffffffa05923d1>] ? ext4_exit_fs+0x109/0x143 [ext4]
>>   [<ffffffff8203d194>] ? put_online_cpus+0x56/0x58
>>   [<ffffffff8206735a>] ? module_refcount+0x85/0x9d
>>   [<ffffffff82067b22>] ? sys_delete_module+0x1b5/0x218
>>   [<ffffffff82074fc3>] ? audit_syscall_entry+0x187/0x1ba
>>   [<ffffffff82002a6b>] ? system_call_fastpath+0x16/0x1b
>> SLAB: cache with size 888 has lost its name
>> SLAB: cache with size 888 has lost its name
>> SLAB: cache with size 888 has lost its name
>> SLAB: cache with size 888 has lost its name
>>
>> The reproduce process is simple:just rmmod ext4 immediately after umount
>> an ext4 volume.
>>
>> I have done some very simple investigation and it seems that with Nick's
>> new ext4_i_callback, even after we do ext4_destroy_inode, it isn't
>> freed. So after we destroy the ext_inode_cache, and when freeing the
>> inode, it errors. Hope it helps. If you have any fixes, I can test it.
>>
>> Regards,
>> Tao
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/
> 

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