| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.16 040/158] powerpc/thp: Add write barrier after updating the valid bit | Date | Mon, 15 Sep 2014 12:24:39 -0700 |
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3.16-stable review patch. If anyone has any objections, please let me know.
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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
commit b0aa44a3dfae3d8f45bd1264349aa87f87b7774f upstream.
With hugepages, we store the hpte valid information in the pte page whose address is stored in the second half of the PMD. Use a write barrier to make sure clearing pmd busy bit and updating hpte valid info are ordered properly.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/powerpc/mm/hugepage-hash64.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/arch/powerpc/mm/hugepage-hash64.c +++ b/arch/powerpc/mm/hugepage-hash64.c @@ -172,8 +172,11 @@ repeat: mark_hpte_slot_valid(hpte_slot_array, index, slot); } /* - * No need to use ldarx/stdcx here + * The hpte valid is stored in the pgtable whose address is in the + * second half of the PMD. Order this against clearing of the busy bit in + * huge pmd. */ + smp_wmb(); *pmdp = __pmd(new_pmd & ~_PAGE_BUSY); return 0; }
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