Re: 2.6.14-rc1-git-now still dying in mm/slab - this time line 1849

[Petr Vandrovec <vandrove@vc.cvut.cz>]

Christoph Lameter wrote:
> On Thu, 22 Sep 2005, Andrew Morton wrote:
>
>
> > Great, thanks.   Christoph, was that patch the final official version?
>
>
> This should deal with the node ownership issue. So yes.
>
> I still have some open question on how pages ended up on the wrong node.
> This should only happen if a zone / node has run out of memory. If pages 
> ended up on the wrong node without that then there may be a different 
> issue still to be fixed.
>
> Maybe Petr can give us some more details on when the problem occurs?

Problem seems to happen immediately, and just first run of cache_reap
(2 seconds after eventd initializes if I understand it correctly) already
finds problem.

But I'm confused.  I've just added code which is supposed to verify all
additions to the cache entry[] (http://platan.vc.cvut.cz/verify-all-entry-add.diff)
on the top of Christoph patch to catch one which later causes problem in cache_reap,
and it logs nothing at the time crash was happening :-(  Only incident it logs is
"while (batchcount > 0)" loop in cache_alloc_refill, saying that

objp ffff81007ffd9430 belonging to the slab ffff81007ffd9000 which belongs
   to node 1 was added to array_cache belonging to node 0 (called from
   ffffffff8016e4a9)  (mm/slab.c ~ line 2430)
... cache avc_node

This repeats couple of times, for avc_node, mnt_cache, proc_inode_cache
and bdev_cache.  Nothing else.

So I've reverted your fix, and still I did not catch offender, so I'm probably
missing some place which populates array_cache entry[] :-(

Only if after I added logging to free_block() I was able to find that offender is
proc_inode_cache.  But I have no idea how this object appeared in the incorrect
node cache...
								Petr

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