Potential issue on UBIFS for Kernel 3.4.7

[Artem Bityutskiy]

On Thu, 2012-08-02 at 14:35 +0200, Fabien Comte wrote:
> Hello,
> 
> I migrated some products (embedded devices with 256 Mbytes NAND flash, about
> 5 products broken by the transition) from a kernel 3.4.4 (they had previous
> versions before 3.4.4) to a 3.4.7. And after a clean shutdown (no power
> cut), I got these messages and some files corrupted (random, not always the
> same).

The only UBIFS change between 3.4.4 and 3.4.7 is:

commit 863c806617059e412ade0b1bbb6d215106be14c1
Author: Artem Bityutskiy <Artem.Bityutskiy at linux.intel.com>
Date:   Sat Jul 14 14:33:09 2012 +0300

    UBIFS: fix a bug in empty space fix-up
    
    commit c6727932cfdb13501108b16c38463c09d5ec7a74 upstream.

I very much doubt it is guilty, but you can check.

But first you need to make sure you have a reliable setup prove that the
upgrade cause the issue.

I'd got this way.

1. Save flash dump of a working device before the upgrade. Make sure you
can always flash this flash image back and the system works fine.
2. Make sure you really have no problems with 3.4.4.
3. Upgrade to 3.4.7, reproduce the issue.
4. Put the saved image back.
5. Try to upgrade to 3.4.5, and see if it is reproducible.
6. Continue bisecting and find the guilty commit. 

-- 
Best Regards,
Artem Bityutskiy
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