There is an ifdef in page_cache_get_speculative() that checks for !SMP
and TREE_RCU, which has been an impossible combination since the advent
of TINY_RCU. The ifdef enables a fastpath that is valid when preemption
is disabled by rcu_read_lock() in UP systems, which is the case when
TINY_RCU is enabled. This commit therefore adjusts the ifdef to generate
the fastpath when TINY_RCU is enabled.
Reported-by: Andi Kleen <a...@firstfloor.org>
Signed-off-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0e38e13..e3dea75 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -149,7 +149,7 @@ static inline int page_cache_get_speculative(struct page
*page)
{
VM_BUG_ON(in_interrupt());
-#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
+#ifdef CONFIG_TINY_RCU
# ifdef CONFIG_PREEMPT_COUNT
VM_BUG_ON(!in_atomic());
# endif
--
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