ACCESS_ONCE does not work reliably on non-scalar types. For
example gcc 4.6 and 4.7 might remove the volatile tag for such
accesses during the SRA (scalar replacement of aggregates) step
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145)
Change the gup code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
Acked-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
---
arch/x86/mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 207d9aef..d754782 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -15,7 +15,7 @@
static inline pte_t gup_get_pte(pte_t *ptep)
{
#ifndef CONFIG_X86_PAE
- return ACCESS_ONCE(*ptep);
+ return READ_ONCE(*ptep);
#else
/*
* With get_user_pages_fast, we walk down the pagetables without taking
--
1.9.3
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