On Tuesday 26 September 2006 12:06, Gennady Dagman wrote:
> Thanks, Charles,
>
> I also tend to think that applying of your latest checkins
> could be the right thing to do.
>
> Could you please only confirm that writing of not erased chunk
> could really cause troubles ? (fs corruptions etc ?)

It is likely to fix #2, but it could fix #1 too.

Of course we shouldn't oops no matter what is on the flash :-).


>
> Regards,
>
> Gennady Dagman.
>
> On Tue, 2006-09-26 at 11:31 +1200, Charles Manning wrote:
> > On Tuesday 26 September 2006 06:11, Gennady Dagman wrote:
> > > Hello,
> > >
> > > We ran into this linux kernel crash during mounting yaffs2 partition
> > > (please find full Oops file attached below)
> > > and from the trace-back and register analysis I conclude that:
> > >
> > > The trace-back function call chain:
> > > get_sb_bdev ->
> > > yaffs_internal_read_super ->
> > > yaffs_GutsInitialise ->
> > > yaffs_CheckpointRestore ->
> > > yaffs_ReadCheckpointData ->
> > > yaffs_ReadCheckpointObjects ->
> > > yaffs_ReadCheckpointTnodes ->
> > > yaffs_AddOrFindLevel0Tnode -> memcpy
> > >
> > > >From the looking into yaffs_AddOrFindLevel0Tnode code it's pretty
> > > > clear
> > >
> > > that the only reason for memcpy
> > > (at the end of yaffs_AddOrFindLevel0Tnode) to crash is having both
> > > fStruct->topLevel = 0 and fStruct->top = 0.
> > >
> > > Looks like this problem is not reproducible easily - we saw it only
> > > ones so far and I suspect
> > > the root cause of it (as well as few others odd problems we run into
> > > from time to time - see, for example,
> > > http://aleph1.co.uk/lurker/message/20060914.181435.951c1454.en.html) is
> > > a flash file system corruption.
> > >
> > > Questions:
> > > ---------------
> > >
> > > 1) Can you imagine what could be the reason (other than flash fs
> > > corruption) for this Oops crash ?
> >
> > I'll have a look at that oops to see what hapopened.
> >
> > > 2) I see that currently in our yaffs code we have defined:
> > >
> > > #define CONFIG_YAFFS_DISABLE_CHUNK_ERASED_CHECK
> > >
> > > means that erasure check of NAND chunks is NOT performed before
> > > write, but I know for sure that from time to time we do encounter
> > > not erased chunks as result of power-off during block erasure.
> > > What could be the consequences of using not erased chunks for
> > > yaffs_WriteChunkWithTagsToNAND ? Could it cause fs corruptions ?
> > > problems like
> > > http://aleph1.co.uk/lurker/message/20060914.181435.951c1454.en.html ??
> > > or this current crash ???
> >
> > Try out the new code I recently checked in for handling the retirement
> > better. Amongst other things this handles the erased checking far better
> > and I hunch it will fix the problem you describe here without burdening
> > you with lots of erase checks.
> >
> > See http://aleph1.co.uk/lurker/message/20060921.084052.7a405cd0.en.html
>
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