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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-20 16:48:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-20 16:48:59 -0800
commit60815cf2e05057db5b78e398d9734c493560b11e (patch)
tree23d7f55df13cc5a0c072cc8a6f361f8e7050b825 /mm/rmap.c
parentbfc7249cc293deac8f2678b7ec3d2407b68c0a33 (diff)
parent5de72a2247ac05bde7c89039631b3d0c6186fafb (diff)
downloadlinux-60815cf2e05057db5b78e398d9734c493560b11e.tar.bz2
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux
Pull ACCESS_ONCE cleanup preparation from Christian Borntraeger: "kernel: Provide READ_ONCE and ASSIGN_ONCE As discussed on LKML http://marc.info/?i=54611D86.4040306%40de.ibm.com ACCESS_ONCE might fail with specific compilers for non-scalar accesses. Here is a set of patches to tackle that problem. The first patch introduce READ_ONCE and ASSIGN_ONCE. If the data structure is larger than the machine word size memcpy is used and a warning is emitted. The next patches fix up several in-tree users of ACCESS_ONCE on non-scalar types. This does not yet contain a patch that forces ACCESS_ONCE to work only on scalar types. This is targetted for the next merge window as Linux next already contains new offenders regarding ACCESS_ONCE vs. non-scalar types" * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/borntraeger/linux: s390/kvm: REPLACE barrier fixup with READ_ONCE arm/spinlock: Replace ACCESS_ONCE with READ_ONCE arm64/spinlock: Replace ACCESS_ONCE READ_ONCE mips/gup: Replace ACCESS_ONCE with READ_ONCE x86/gup: Replace ACCESS_ONCE with READ_ONCE x86/spinlock: Replace ACCESS_ONCE with READ_ONCE mm: replace ACCESS_ONCE with READ_ONCE or barriers kernel: Provide READ_ONCE and ASSIGN_ONCE
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 45ba250babd8..c5bc241127b2 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -583,7 +583,8 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
* without holding anon_vma lock for write. So when looking for a
* genuine pmde (in which to find pte), test present and !THP together.
*/
- pmde = ACCESS_ONCE(*pmd);
+ pmde = *pmd;
+ barrier();
if (!pmd_present(pmde) || pmd_trans_huge(pmde))
pmd = NULL;
out: