This is a note to let you know that I've just added the patch titled
ppc/hugetlbfs: Replace ACCESS_ONCE with READ_ONCE
to the 3.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ppc-hugetlbfs-replace-access_once-with-read_once.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From da1a288d8562739aa8ba0273d4fb6b73b856c0d3 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Date: Tue, 6 Jan 2015 22:47:41 +0100
Subject: ppc/hugetlbfs: Replace ACCESS_ONCE with READ_ONCE
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
commit da1a288d8562739aa8ba0273d4fb6b73b856c0d3 upstream.
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 ppc/hugetlbfs code to replace ACCESS_ONCE with READ_ONCE.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/hugetlbpage.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -978,7 +978,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *
*/
pdshift = PUD_SHIFT;
pudp = pud_offset(&pgd, ea);
- pud = ACCESS_ONCE(*pudp);
+ pud = READ_ONCE(*pudp);
if (pud_none(pud))
return NULL;
@@ -990,7 +990,7 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *
else {
pdshift = PMD_SHIFT;
pmdp = pmd_offset(&pud, ea);
- pmd = ACCESS_ONCE(*pmdp);
+ pmd = READ_ONCE(*pmdp);
/*
* A hugepage collapse is captured by pmd_none, because
* it mark the pmd none and do a hpte invalidate.
Patches currently in stable-queue which might be from borntraeger@xxxxxxxxxx are
queue-3.19/x86-spinlocks-paravirt-fix-memory-corruption-on-unlock.patch
queue-3.19/ppc-hugetlbfs-replace-access_once-with-read_once.patch
queue-3.19/mm-gup-replace-access_once-with-read_once.patch
queue-3.19/kernel-make-read_once-valid-on-const-arguments.patch
queue-3.19/kvm-s390-base-hrtimer-on-a-monotonic-clock.patch
queue-3.19/kernel-tighten-rules-for-access-once.patch
queue-3.19/next-sh-fix-compile-error.patch
queue-3.19/kvm-s390-floating-irqs-fix-user-triggerable-endless-loop.patch
queue-3.19/kvm-s390-forward-hrtimer-if-guest-ckc-not-pending-yet.patch
queue-3.19/ppc-kvm-replace-access_once-with-read_once.patch
queue-3.19/kernel-fix-sparse-warning-for-access_once.patch
queue-3.19/kvm-s390-avoid-memory-leaks-if-__inject_vm-fails.patch
queue-3.19/x86-xen-p2m-replace-access_once-with-read_once.patch
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