From 38c5ce936a0862a6ce2c8d1c72689a3aba301425 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Tue, 6 Jan 2015 22:54:46 +0100
Subject: [PATCH] mm/gup: Replace ACCESS_ONCE with READ_ONCE
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)
Fixup gup_pmd_range.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
mm/gup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index a900759cc807..bed30efad77c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -926,7 +926,7 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
pmdp = pmd_offset(&pud, addr);
do {
- pmd_t pmd = ACCESS_ONCE(*pmdp);
+ pmd_t pmd = READ_ONCE(*pmdp);
next = pmd_addr_end(addr, end);
if (pmd_none(pmd) || pmd_trans_splitting(pmd))
--
2.42.0