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

From: Roman Kononov
Date: Tue Jan 06 2009 - 11:17:19 EST


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.

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