powerpc: Update find_linux_pte_or_hugepte to handle transparent hugepages

Reviewed-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 26 insertions, 6 deletions

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 2865077e0159..49282045ee96 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -936,30 +936,50 @@ pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift
 
         pg = pgdir + pgd_index(ea);
 
-        if (pgd_huge(*pg)) {
+        /*
+         * we should first check for none. That takes care of a
+         * a parallel hugetlb or THP pagefault moving none entries
+         * to respective types.
+         */
+        if (pgd_none(*pg))
+                return NULL;
+        else if (pgd_huge(*pg)) {
                 ret_pte = (pte_t *) pg;
                 goto out;
         } else if (is_hugepd(pg))
                 hpdp = (hugepd_t *)pg;
-        else if (!pgd_none(*pg)) {
+        else {
                 pdshift = PUD_SHIFT;
                 pu = pud_offset(pg, ea);
 
-                if (pud_huge(*pu)) {
+                if (pud_none(*pu))
+                        return NULL;
+                else if (pud_huge(*pu)) {
                         ret_pte = (pte_t *) pu;
                         goto out;
                 } else if (is_hugepd(pu))
                         hpdp = (hugepd_t *)pu;
-                else if (!pud_none(*pu)) {
+                else {
                         pdshift = PMD_SHIFT;
                         pm = pmd_offset(pu, ea);
+                        /*
+                         * A hugepage collapse is captured by pmd_none, because
+                         * it mark the pmd none and do a hpte invalidate.
+                         *
+                         * A hugepage split is captured by pmd_trans_splitting
+                         * because we mark the pmd trans splitting and do a
+                         * hpte invalidate
+                         *
+                         */
+                        if (pmd_none(*pm) || pmd_trans_splitting(*pm))
+                                return NULL;
 
-                        if (pmd_huge(*pm)) {
+                        if (pmd_huge(*pm) || pmd_large(*pm)) {
                                 ret_pte = (pte_t *) pm;
                                 goto out;
                         } else if (is_hugepd(pm))
                                 hpdp = (hugepd_t *)pm;
-                        else if (!pmd_none(*pm))
+                        else
                                 return pte_offset_kernel(pm, ea);
                 }
         }