]> git.hungrycats.org Git - linux/commitdiff
mm/gup: Replace ACCESS_ONCE with READ_ONCE
authorChristian Borntraeger <borntraeger@de.ibm.com>
Tue, 6 Jan 2015 21:54:46 +0000 (22:54 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 6 Mar 2015 22:57:43 +0000 (14:57 -0800)
commit 38c5ce936a0862a6ce2c8d1c72689a3aba301425 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
mm/gup.c

index 8dd50ce6326fd50540b24fe6e93d12546b20594a..9b2afbfe67e3905da6d7413621c01e8674a4d759 100644 (file)
--- 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))