Merge branches 'arm/rockchip', 'arm/exynos', 'arm/smmu', 'x86/vt-d', 'x86/amd', ...

[sfrench/cifs-2.6.git] / arch / powerpc / mm / pgtable_64.c

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 59daa5eeec2526ae481a5dda586c629a985813d7..6bfadf1aa5cbbfadbd7237e5f3da8ac8653a5651 100644 (file)
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -839,6 +839,17 @@ pmd_t pmdp_get_and_clear(struct mm_struct *mm,
         * hash fault look at them.
         */
        memset(pgtable, 0, PTE_FRAG_SIZE);
+       /*
+        * Serialize against find_linux_pte_or_hugepte which does lock-less
+        * lookup in page tables with local interrupts disabled. For huge pages
+        * it casts pmd_t to pte_t. Since format of pte_t is different from
+        * pmd_t we want to prevent transit from pmd pointing to page table
+        * to pmd pointing to huge page (and back) while interrupts are disabled.
+        * We clear pmd to possibly replace it with page table pointer in
+        * different code paths. So make sure we wait for the parallel
+        * find_linux_pte_or_hugepage to finish.
+        */
+       kick_all_cpus_sync();
        return old_pmd;
 }