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

Eric Sandeen
2011-01-26T20:40:52Z

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
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