From: Joerg Roedel <jroe...@suse.de>

With huge-page ioremap areas the unmappings also need to be
synced between all page-tables. Otherwise it can cause data
corruption when a region is unmapped and later re-used.

Make the vmalloc_sync_one() function ready to sync
unmappings.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 arch/x86/mm/fault.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 4a4049f6d458..d71e167662c3 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -194,11 +194,12 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, 
unsigned long address)
 
        pmd = pmd_offset(pud, address);
        pmd_k = pmd_offset(pud_k, address);
-       if (!pmd_present(*pmd_k))
-               return NULL;
 
-       if (!pmd_present(*pmd))
+       if (pmd_present(*pmd) ^ pmd_present(*pmd_k))
                set_pmd(pmd, *pmd_k);
+
+       if (!pmd_present(*pmd_k))
+               return NULL;
        else
                BUG_ON(pmd_pfn(*pmd) != pmd_pfn(*pmd_k));
 
-- 
2.17.1

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