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authorNicholas Piggin <npiggin@gmail.com>2019-06-07 06:56:36 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2019-06-07 09:28:28 +0300
commita00196a272161338d4b1d66ec69e3d57c6b280e0 (patch)
tree8c1b21d16a2fede66919f4809292087fde2a3215 /arch
parent33258a1db165cf43a9e6382587ad06e9b7f8187c (diff)
downloadlinux-a00196a272161338d4b1d66ec69e3d57c6b280e0.tar.xz
powerpc/64s: __find_linux_pte() synchronization vs pmdp_invalidate()
The change to pmdp_invalidate() to mark the pmd with _PAGE_INVALID broke the synchronisation against lock free lookups, __find_linux_pte()'s pmd_none() check no longer returns true for such cases. Fix this by adding a check for this condition as well. Fixes: da7ad366b497 ("powerpc/mm/book3s: Update pmd_present to look at _PAGE_PRESENT bit") Cc: stable@vger.kernel.org # v4.20+ Suggested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/mm/pgtable.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index db4a6253df92..533fc6fa6726 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -372,13 +372,25 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
pdshift = PMD_SHIFT;
pmdp = pmd_offset(&pud, ea);
pmd = READ_ONCE(*pmdp);
+
/*
- * A hugepage collapse is captured by pmd_none, because
- * it mark the pmd none and do a hpte invalidate.
+ * A hugepage collapse is captured by this condition, see
+ * pmdp_collapse_flush.
*/
if (pmd_none(pmd))
return NULL;
+#ifdef CONFIG_PPC_BOOK3S_64
+ /*
+ * A hugepage split is captured by this condition, see
+ * pmdp_invalidate.
+ *
+ * Huge page modification can be caught here too.
+ */
+ if (pmd_is_serializing(pmd))
+ return NULL;
+#endif
+
if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
if (is_thp)
*is_thp = true;