Re: 2.6.18-rc3-mm2: rcu radix tree patches break page migration

[Nick Piggin <nickpiggin@yahoo.com.au>]

Christoph Lameter wrote:
> If I take the following patches out then page migration works reliably 
> again. Otherwise page migration may result in weird values in the
> page struct. Reproduce by trying to migrate the executable pages
> of a running process. This usually creates enough races to break things.
> AFAIK the current radix tree rcu patches do not change the behavior
> of the tree_lock at all.
> 
> radix-tree-rcu-lockless-readside.patch
> redo-radix-tree-fixes.patch
> adix-tree-rcu-lockless-readside-update.patch
> radix-tree-rcu-lockless-readside-semicolon.patch
> adix-tree-rcu-lockless-readside-update-tidy.patch
> adix-tree-rcu-lockless-readside-fix-2.patch
> 
> Output in one failure scenario (after migrating the memory of cron back 
> and forth between nodes):

Yeah Lee noticed this as well...

Question: can you replace the lookup_slot with a regular lookup, then
replace the pointer switch with a radix_tree_delete + radix_tree_insert
and see if that works?

Thanks,
Nick

-- 
SUSE Labs, Novell Inc.
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