>From f7b73c6b4508fe9b141a43d92be2f9dd7d3c4a58 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu <[email protected]> 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 <[email protected]> Signed-off-by: Aneesh Kumar K.V <[email protected]> Signed-off-by: Sukadev Bhattiprolu <[email protected]> Tested-by: James Dykman <[email protected]> --- 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
