UBIFS failure & stable page writes

[Prins Anton (ST-CO/ENG1.1)]

Another weekend of tests, including the patches showed no more logging of writing orphan node 0.
Also the 0xdead4ead did not appear; so the patches certainly do their job!

We do not have hard evidence the missing root node is caused by this 'writing of free-ed memory'.
But at least it seems a good suspect! Because the occurrence is very low we will continue testing...
(And go back mounting synchronous to get some higher occurrence...)

I'll keep you up-to-date.

Anton


-----Original Message-----
From: Adrian Hunter [mailto:adrian.hunter at intel.com] 
Sent: dinsdag 18 juni 2013 9:01
To: Prins Anton (ST-CO/ENG1.1)
Cc: Mats Kärrman; linux-mtd at lists.infradead.org; dedekind1 at gmail.com
Subject: Re: UBIFS failure & stable page writes

On 18/06/13 09:31, Prins Anton (ST-CO/ENG1.1) wrote:
> Last night I did do additional tests with create/remove of files in a
> while loop on a synchronous mounted UBIFS. I did NOT get any node 0 or 1
> written over this night, but obvious enough I saw some strange node id in
> the orphan area: 0xdead4ead
> 
> 0xdead4ead Is known to me as SPINLOCK_MAGIC; but no glue why It is in the
> orphan area if node number... Is something known about 0xdead4ead?

I am afraid I have not had time to analyze the effects of the double-free
but it is reasonable to assume that UBIFS may be writing an orphan from a
structure that has been freed and therefore re-used by, for example in this
case, a spinlock.