From: Eric Sandeen <sandeen@redhat.com>
Subject: Re: 38-rc1: umount+rmmod cause ext4 error.
Date: Wed, 26 Jan 2011 14:40:44 -0600
Message-ID: <4D4086CC.5050309@redhat.com>
References: <4D368A70.5030103@tao.ma> <201101262128.25528.maciej.rutecki@gmail.com>
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Cc: Tao Ma <tm@tao.ma>, npiggin@gmail.com,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	linux-ext4@vger.kernel.org, Theodore Tso <tytso@mit.edu>
To: maciej.rutecki@gmail.com
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On 1/26/11 2:28 PM, Maciej Rutecki wrote:
> I created a Bugzilla entry at=20
> https://bugzilla.kernel.org/show_bug.cgi?id=3D27652
> 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=3Dlinux-ext4&m=3D129546975702198&w=3D2
and
http://marc.info/?l=3Dlinux-ext4&m=3D129527644524410&w=3D2

that'd be great.

Thanks,
-Eric

> On =C5=9Broda, 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 wi=
th
>> 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 um=
ount
>> an ext4 volume.
>>
>> I have done some very simple investigation and it seems that with Ni=
ck'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 i=
t.
>>
>> Regards,
>> Tao
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>=20

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