MTD : Kernel oops when remounting ubifs as read/write

[Mark Jackson]

On 12/03/13 11:25, Artem Bityutskiy wrote:
> On Mon, 2013-03-04 at 16:42 +0000, Mark Jackson wrote:
>> I'm encountering an oops when remounting my ubifs volume as read/write.
>>
>> # mount -o remount,rw /
>> [   89.434974] UBIFS assert failed in ubifs_write_node at 869 (pid 628)
>> [   89.442122] [<c001b124>] (unwind_backtrace+0x0/0xf0) from [<c01ad7d4>] (ubifs_write_node+0x180/0x1c4)
>> [   89.451896] [<c01ad7d4>] (ubifs_write_node+0x180/0x1c4) from [<c01b3878>] (ubifs_write_master+0x9c/0x134)
>> [   89.462018] [<c01b3878>] (ubifs_write_master+0x9c/0x134) from [<c01a79a4>] (ubifs_remount_fs+0x5d4/0x7f8)
>> [   89.472133] [<c01a79a4>] (ubifs_remount_fs+0x5d4/0x7f8) from [<c010dbf4>] (do_remount_sb+0x98/0x16c)
>> [   89.481790] [<c010dbf4>] (do_remount_sb+0x98/0x16c) from [<c0128268>] (do_mount+0x830/0x888)
>> [   89.490708] [<c0128268>] (do_mount+0x830/0x888) from [<c0128344>] (sys_mount+0x84/0xb8)
>> [   89.499178] [<c0128344>] (sys_mount+0x84/0xb8) from [<c0013800>] (ret_fast_syscall+0x0/0x3c)
>> [   89.510997] UBIFS assert failed in ubifs_write_node at 869 (pid 628)
>> [   89.517884] [<c001b124>] (unwind_backtrace+0x0/0xf0) from [<c01ad7d4>] (ubifs_write_node+0x180/0x1c4)
>> [   89.527641] [<c01ad7d4>] (ubifs_write_node+0x180/0x1c4) from [<c01b38b4>] (ubifs_write_master+0xd8/0x134)
>> [   89.537760] [<c01b38b4>] (ubifs_write_master+0xd8/0x134) from [<c01a79a4>] (ubifs_remount_fs+0x5d4/0x7f8)
>> [   89.547869] [<c01a79a4>] (ubifs_remount_fs+0x5d4/0x7f8) from [<c010dbf4>] (do_remount_sb+0x98/0x16c)
>> [   89.557526] [<c010dbf4>] (do_remount_sb+0x98/0x16c) from [<c0128268>] (do_mount+0x830/0x888)
>> [   89.566435] [<c0128268>] (do_mount+0x830/0x888) from [<c0128344>] (sys_mount+0x84/0xb8)
>> [   89.574905] [<c0128344>] (sys_mount+0x84/0xb8) from [<c0013800>] (ret_fast_syscall+0x0/0x3c)
>> [   89.585939] UBIFS: start fixing up free space
>> [   89.592237] UBIFS: background thread "ubifs_bgt0_0" started, PID 629
>> [   91.419951] UBIFS: free space fixup complete
>> #
>>
>> If it's any help, if the remount is put into my inittab, I don't get any oops.
> 
> Would you please try this patch (also attached):
> 
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index ac838b8..9791b3c 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -1568,6 +1568,12 @@ static int ubifs_remount_rw(struct ubifs_info *c)
>  	c->remounting_rw = 1;
>  	c->ro_mount = 0;
>  
> +	if (c->space_fixup) {
> +		err = ubifs_fixup_free_space(c);
> +		if (err)
> +			goto out;
> +	}
> +
>  	err = check_free_space(c);
>  	if (err)
>  		goto out;
> @@ -1684,12 +1690,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
>  		err = dbg_check_space_info(c);
>  	}
>  
> -	if (c->space_fixup) {
> -		err = ubifs_fixup_free_space(c);
> -		if (err)
> -			goto out;
> -	}
> -
>  	mutex_unlock(&c->umount_mutex);
>  	return err;
> 

Sorry ... this just locks up the unit.

Mark J.