From f7b73c6b4508fe9b141a43d92be2f9dd7d3c4a58 Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Date: Thu, 24 Mar 2016 02:07:57 -0400
Subject: [PATCH 1/1] powerpc/mm: Add memory barrier in __hugepte_alloc()
__hugepte_alloc() uses kmem_cache_zalloc() to allocate a zeroed PTE
and proceeds to use the newly allocated PTE. Add a memory barrier to
make sure that the other CPUs see a properly initialized PTE.
Based on a fix suggested by James Dykman.
Reported-by: James Dykman <jdyk...@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
Tested-by: James Dykman <jdyk...@us.ibm.com>
---
Note:
The bug was encountered and fix tested on an older version
of the kernel. Forward porting to mainline.
---
arch/powerpc/mm/hugetlbpage.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index d991b9e..081f679 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -81,6 +81,13 @@ static int __hugepte_alloc(struct mm_struct *mm, hugepd_t
*hpdp,
if (! new)
return -ENOMEM;
+ /*
+ * Make sure other cpus find the hugepd set only after a
+ * properly initialized page table is visible to them.
+ * For more details look for comment in __pte_alloc().
+ */
+ smp_wmb();
+
spin_lock(&mm->page_table_lock);
#ifdef CONFIG_PPC_FSL_BOOK3E
/*
--
1.8.3.1
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