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Re: JFFS2 Garbage Collection Error?


Scott Wilkinson said:
> Hi All,
>
> I have been running JFFS2 tests on both the Linux Synthetic Target (with
> synthetic flash driver) and on a PPC embedded system.  I have a simple
> test which loops forever doing the following:
>
> for (N=0;;N++)
> {
>   a) Create File(N), fill with known pattern
>   if (N>0)
>   {
>     b) Open File(N-1), verify known pattern
>     c) Delete File(N-1)
>   }
> }
>
> What I see is that on both the synthetic and real target the exact same
> behavior happens.  Everything works fine until the first time that
> jffs2_garbage_collect_dnode() gets called.  A few more calls down the
> stack and I take and exception caused by rb_remove_color dereferencing a
> null pointer.
>
> Has anyone seen anything like this?  If you are successfully using
> JFFS2, have you ever seen jffs2_garbage_collect_dnode() get called?
>
> I have attached the test code I'm using.  For the synthetic target I
> have the flash configured to be 8 sectors of 65536 bytes each.  In this
> case it fails when N = 2797.
>
> I am not really sure where to start looking.  I have actually merged the
> latest jffs2 code from www.intradead.org and it runs(!) but didn't fix
> the problem :(.
>

The JFFS2 garbage collection is a known issue - for example,
the timer which is supposed to kick off things (based on the
Linux 'jiffies') is not well defined, etc.

Have you asked the JFFS2 folks (David Woodhouse in particular)
about these problems?  He might have more insight.

.--------------------------------------------------------.
|       Mind: Embedded Linux and eCos Development        |
|--------------------------------------------------------|
| Gary Thomas              email:  gary.thomas@mind.be   |
| Mind ( http://mind.be )  tel:    +1 (970) 229-1963     |
| gpg: http://www.chez-thomas.org/gary/gpg_key.asc       |
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