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mm/gup: Replace ACCESS_ONCE with READ_ONCE

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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>
This commit is contained in:
Christian Borntraeger 2015-01-06 22:54:46 +01:00
commit 38c5ce936a
1 changed files with 1 additions and 1 deletions
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2
mm/gup.c
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@ -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))