Commit 7e467245 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Benjamin Herrenschmidt

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: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 969b7b20
...@@ -84,7 +84,9 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, ...@@ -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 * atomically mark the linux large page PMD busy and dirty
*/ */
do { do {
old_pmd = pmd_val(*pmdp); pmd_t pmd = ACCESS_ONCE(*pmdp);
old_pmd = pmd_val(pmd);
/* If PMD busy, retry the access */ /* If PMD busy, retry the access */
if (unlikely(old_pmd & _PAGE_BUSY)) if (unlikely(old_pmd & _PAGE_BUSY))
return 0; return 0;
......
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