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

Maciej Rutecki
2011-01-26T20:31:55Z

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