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authorAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2014-08-13 12:32:02 +0530
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-08-13 18:20:41 +1000
commit7e467245bf5226db34c4b12d3cbacfa2f7a15a8b (patch)
tree943f6aa4fe6c82e64372cbac2f5e2f94dc015419 /arch/powerpc
parent969b7b208f7408712a3526856e4ae60ad13f6928 (diff)
downloadop-kernel-dev-7e467245bf5226db34c4b12d3cbacfa2f7a15a8b.zip
op-kernel-dev-7e467245bf5226db34c4b12d3cbacfa2f7a15a8b.tar.gz
powerpc/thp: Use ACCESS_ONCE when loading pmdp
We would get wrong results in compiler recomputed old_pmd. Avoid that by using ACCESS_ONCE CC: <stable@vger.kernel.org> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/mm/hugepage-hash64.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/powerpc/mm/hugepage-hash64.c b/arch/powerpc/mm/hugepage-hash64.c
index 1fb609d..5f5e632 100644
--- a/arch/powerpc/mm/hugepage-hash64.c
+++ b/arch/powerpc/mm/hugepage-hash64.c
@@ -84,7 +84,9 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
* atomically mark the linux large page PMD busy and dirty
*/
do {
- old_pmd = pmd_val(*pmdp);
+ pmd_t pmd = ACCESS_ONCE(*pmdp);
+
+ old_pmd = pmd_val(pmd);
/* If PMD busy, retry the access */
if (unlikely(old_pmd & _PAGE_BUSY))
return 0;
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