[patch] mm: fix lockless pagecache reordering bug (was Re: BUG: soft lockup - is this XFS problem?)

[Roman Kononov]

On 2009-01-05 20:05 Nick Piggin said the following:
> Subject: mm lockless pagecache barrier fix
>  static inline void *radix_tree_deref_slot(void **pslot)
>  {
> -	void *ret = *pslot;
> +	void *ret = rcu_dereference(*pslot);
>  	if (unlikely(radix_tree_is_indirect_ptr(ret)))
>  		ret = RADIX_TREE_RETRY;
>  	return ret;

3 systems are working fine for a few hours with the patch. They would 
fail within 20 minutes without it.

Thanks.