Re: UBI leb_write_unlock NULL pointer Oops (continuation)

[Richard Weinberger <richard@nod.at>]

Am 05.02.2014 22:45, schrieb Bill Pringlemeir:
> 
>> Am 04.02.2014 18:01, schrieb Wiedemer, Thorsten (Lawo AG):
> 
>>> I made a "hardcore test" with:
>>> $ while [ 1 ]; do cp <8kByte_file> tmp/<8kByte_file.1>; sync; done &
>>> $ while [ 1 ]; do cp <8kByte_file> tmp/<8kByte_file.2>; sync; done &
>>> $ while [ 1 ]; do cp <8kByte_file> tmp/<8kByte_file.3>; sync; done &
> 
>>> It took about 2-3 hours until I had an error (two times):
> 
> On  5 Feb 2014, richard@nod.at wrote:
> 
>> This test ran the over night without any error on my imx51 board. :-\
> 
>> Bill's great analysis showed that it may be a linked list corruption
>> in rw_semaphore.  Thorsten, can you please enable CONFIG_DEBUG_LIST?
>> Also try whether you can trigger the issue with lock debugging
>> enabled.
> 
> I am trying to run the same test.  I have 'fastmap' enabled and
> 'kmemleak'.  I have various occurrences of these two,

Did you backport all UBI/Fastmap fixes?
Fastmap saw some memory leak fixes.

> unreferenced object 0xc2c06e50 (size 24):
>   comm "sync", pid 2941, jiffies 855335 (age 6354.950s)
>   hex dump (first 24 bytes):
>     5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 79 00 00 00  ZZZZZZZZZZZZy...
>     07 00 00 00 5a 5a 5a a5                          ....ZZZ.
>   backtrace:
>     [<c019a544>] kmem_cache_alloc+0x10c/0x1a0

Can you please decode the line number?

>     [<c02b2b6c>] ubi_update_fastmap+0xdc/0x14f4
>     [<c02ac204>] ubi_wl_get_peb+0x28/0xbc
>     [<c02a64c0>] ubi_eba_write_leb+0x23c/0x884
>     [<c02a51a4>] ubi_leb_write+0xc4/0xe0
>     [<c0200f38>] ubifs_leb_write+0x9c/0x130
>     [<c020b28c>] ubifs_log_start_commit+0x230/0x3f4
>     [<c020c368>] do_commit+0x134/0x870
>     [<c01fbfa0>] ubifs_sync_fs+0x88/0x9c
>     [<c01c30bc>] __sync_filesystem+0x74/0x98
>     [<c01a2860>] iterate_supers+0x9c/0x104
>     [<c01c31f4>] sys_sync+0x3c/0x68
>     [<c0129300>] ret_fast_syscall+0x0/0x1c
>     [<ffffffff>] 0xffffffff
> unreferenced object 0xc2c06df0 (size 24):
>   comm "flush-ubifs_0_3", pid 260, jiffies 867487 (age 6233.430s)
>   hex dump (first 24 bytes):
>     5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 7a 00 00 00  ZZZZZZZZZZZZz...
>     1e 00 00 00 5a 5a 5a a5                          ....ZZZ.
>   backtrace:
>     [<c019a544>] kmem_cache_alloc+0x10c/0x1a0

Here too.

>     [<c02b2b6c>] ubi_update_fastmap+0xdc/0x14f4
>     [<c02ac204>] ubi_wl_get_peb+0x28/0xbc
>     [<c02a64c0>] ubi_eba_write_leb+0x23c/0x884
>     [<c02a50c0>] ubi_leb_map+0x70/0x90
>     [<c020125c>] ubifs_leb_map+0x74/0x100
>     [<c020af44>] ubifs_add_bud_to_log+0x1f4/0x30c
>     [<c01f4830>] make_reservation+0x2e0/0x3e0
>     [<c01f53e8>] ubifs_jnl_write_data+0xfc/0x25c
>     [<c01f838c>] do_writepage+0x88/0x260
>     [<c017b368>] __writepage+0x18/0x84
>     [<c017b98c>] write_cache_pages+0x1b4/0x3ac
>     [<c01bead4>] writeback_single_inode+0x9c/0x258
>     [<c01befac>] writeback_sb_inodes+0xbc/0x180
>     [<c01bf6c0>] writeback_inodes_wb+0x7c/0x178
>     [<c01bfa00>] wb_writeback+0x244/0x2ac
> 
> It is a 'cache' so I am suspicious of the kmemleak (also my Linux is old
> [kmemleak] with the Ubi/UbiFs/Mtd patches).  However, I just wondered if
> Thorsten has posted a .config somewhere?  I am testing on an IMX25
> system as well and trying to replicate with his test.  The Linux version
> is different as well.  I suspect Richard will have tried with 'fastmap'
> as well?  Are you running without 'fastmap' Thorsten?  I will let my
> system run over night.  Maybe just,
> 
>  $ grep -E 'MTD|UBI' .config | grep -v '^#'

I think the issue is not related to fastmap because we have reports for kernels older
than 3.7.
Fastmap got merged in 3.7.

Thanks,
//richard