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 <borntraeger@xxxxxxxxxx> --- 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
