This is a note to let you know that I've just added the patch titled
powerpc/thp: Add write barrier after updating the valid bit
to the 3.16-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:
powerpc-thp-add-write-barrier-after-updating-the-valid-bit.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b0aa44a3dfae3d8f45bd1264349aa87f87b7774f Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Date: Wed, 13 Aug 2014 12:31:57 +0530
Subject: powerpc/thp: Add write barrier after updating the valid bit
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from aneesh.kumar@xxxxxxxxxxxxxxxxxx are
queue-3.16/powerpc-thp-use-access_once-when-loading-pmdp.patch
queue-3.16/powerpc-thp-add-write-barrier-after-updating-the-valid-bit.patch
queue-3.16/powerpc-mm-use-read-barrier-when-creating-real_pte.patch
queue-3.16/powerpc-thp-handle-combo-pages-in-invalidate.patch
queue-3.16/powerpc-thp-invalidate-old-64k-based-hash-page-mapping-before-insert-of-4k-pte.patch
queue-3.16/powerpc-thp-invalidate-with-vpn-in-loop.patch
queue-3.16/powerpc-thp-don-t-recompute-vsid-and-ssize-in-loop-on-invalidate.patch
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