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| author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2013-06-20 11:00:23 +0200 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2013-06-21 08:01:56 +0200 |
| commit | 7888b4ddb44dccd68bc20d0dc4425707dff88c72 (patch) | |
| tree | 7d9b5d74f6f51255fe06649511bf39d1a0516356 /arch/powerpc/mm/hugetlbpage.c | |
| parent | powerpc: Make linux pagetable walk safe with THP enabled (diff) | |
| download | linux-7888b4ddb44dccd68bc20d0dc4425707dff88c72.tar.xz linux-7888b4ddb44dccd68bc20d0dc4425707dff88c72.zip | |
powerpc: Prevent gcc to re-read the pagetables
GCC is very likely to read the pagetables just once and cache them in
the local stack or in a register, but it is can also decide to re-read
the pagetables. The problem is that the pagetable in those places can
change from under gcc.
With THP/hugetlbfs the pmd (and pgd for hugetlbfs giga pages) can
change under gup_fast. The pages won't be freed untill we finish
gup fast because we have irq disabled and we free these pages via
rcu callback.
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/mm/hugetlbpage.c')
| -rw-r--r-- | arch/powerpc/mm/hugetlbpage.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index e9e6882231da..f2f01fd3ec68 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -1024,7 +1024,7 @@ int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, if (pte_end < end) end = pte_end; - pte = *ptep; + pte = ACCESS_ONCE(*ptep); mask = _PAGE_PRESENT | _PAGE_USER; if (write) mask |= _PAGE_RW; |