BUG in JFFS2 kernel 2.6.27

[joakim.tjernlund at transmode.se]

Anders Grafström <grfstrm at users.sourceforge.net> wrote on 13/01/2009 
15:36:43:

> From:
> 
> Anders Grafström <grfstrm at users.sourceforge.net>
> 
> To:
> 
> joakim.tjernlund at transmode.se
> 
> Cc:
> 
> linux-mtd at lists.infradead.org
> 
> Date:
> 
> 13/01/2009 15:37
> 
> Subject:
> 
> Re: BUG in JFFS2 kernel 2.6.27
> 
> joakim.tjernlund at transmode.se wrote:
> > Just got this BUG:
> > 
> > Data CRC 22c90447 != calculated CRC cbf47f8b for node at 07d2aadc
> > ------------[ cut here ]------------
> > kernel               BUG               at fs/jffs2/file.c:251!
> > Oops:      Exception      in      kernel      mode,     sig:     5 
[#1]
> > TMCUTU
> > NIP:        c00eb5d0        LR:        c004ab34        CTR: c00eb57c
> > REGS:      ce217bf0      TRAP:     0700       Not     tainted (2.6.27)
> > MSR:     00029032    <EE,ME,IR,DR>     CR:    24022422     XER: 
00000000
> > TASK       =       ce1d6800[424]      'ne_swumd'      THREAD: ce216000
> > GPR00:  00000001  ce217ca0  ce1d6800  ce296520  cf51b708  00000000 
002a6000
> > 00001000
> > GPR08:  00001000  00000000  c016bac4  cf86f600  00400000  10069018 
10060000
> > 00000000
> > GPR16:  002a6000  00000000  00000000  c021010c  00000000  ce296520 
cf86f400
> > cf51b648
> > GPR24:  00000000  00001000  00000000  002a6000  00000000  cf51b670 
ce216000
> > c0441820
> > NIP                  [c00eb5d0] jffs2_write_end+0x54/0x228
> > LR            [c004ab34] generic_file_buffered_write+0x178/0x634
> > Call Trace:
> > [ce217ca0]       [c016aa94]       release_sock+0x94/0xa8 (unreliable)
> > [ce217ce0]        [c004ab34] generic_file_buffered_write+0x178/0x634
> > [ce217d70]      [c004b394] __generic_file_aio_write_nolock+0x3a4/0x568
> > [ce217df0]           [c004b6b0] generic_file_aio_write+0x68/0x120
> > [ce217e20]                [c006a1a4] do_sync_write+0xc8/0x13c
> > [ce217ef0]                  [c006a2b4] vfs_write+0x9c/0x174
> > [ce217f10]                  [c006a468] sys_write+0x4c/0x90
> > [ce217f40]               [c000f3ec] ret_from_syscall+0x0/0x38
> > --- Exception: c01 at 0xf9c1744
> >     LR = 0x1003ce20
> > Instruction dump:
> > 83a40000 7f384214 54dc053a 817d008c 82cb019c 92e10008 3afdffd8 
80090000
> > 70090008  41820004  7c000026 54001ffe <0f000000> 6b291000 7d2bfe70 
7d604a78
> > ---[ end trace 79c27f7a1b03cf81 ]---
> > 
> > Anyone seen something similar?
> 
> I think it's this one again:
> http://lists.infradead.org/pipermail/linux-mtd/2008-April/021473.html
> 
> The patch in the above post avoids this BUG_ON by aborting early 
> when the dnode
> read fails and propagates an error code back to userspace and thus 
> avoids this path to be taken.

This seems like the right thing to do. Why test the return value from 
jffs2_do_readpage_nolock()
if it always returns 0? If this is enough though is unclear to me.

David?

> 
> I didn't pursue it since I was unsure whether it would remove some
> self-healing properties of the design in non-debug builds.
>