From 3d3cbaa572e21ab7e9dc1c9025351e05640ec044 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Date: Tue, 28 May 2019 11:06:24 +0530
Subject: [PATCH] powerpc/mm: Handle page table allocation failures

References: bsc#1065729
Patch-mainline: v5.3-rc1
Git-commit: 2230ebf6e6dd0b7751e2921b40f6cfe34f09bb16

This fixes kernel crash that arises due to not handling page table allocation
failures while allocating hugetlb page table.

Fixes: e2b3d202d1db ("powerpc: Switch 16GB and 16MB explicit hugepages to a different page table format")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/mm/hugetlbpage.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 5f7998bd6101..769e276b4840 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -171,6 +171,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
 	else {
 		pdshift = PUD_SHIFT;
 		pu = pud_alloc(mm, pg, addr);
+		if (!pu)
+			return NULL;
 		if (pshift == PUD_SHIFT)
 			return (pte_t *)pu;
 		else if (pshift > PMD_SHIFT)
@@ -178,6 +180,8 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
 		else {
 			pdshift = PMD_SHIFT;
 			pm = pmd_alloc(mm, pu, addr);
+			if (!pm)
+				return NULL;
 			if (pshift == PMD_SHIFT)
 				/* 16MB hugepage */
 				return (pte_t *)pm;
@@ -191,11 +195,16 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz
 	} else {
 		pdshift = PUD_SHIFT;
 		pu = pud_alloc(mm, pg, addr);
+		if (!pu)
+			return NULL;
 		if (pshift >= HUGEPD_PUD_SHIFT) {
 			hpdp = (hugepd_t *)pu;
 		} else {
 			pdshift = PMD_SHIFT;
 			pm = pmd_alloc(mm, pu, addr);
+			if (!pm)
+				return NULL;
+			ptl = pmd_lockptr(mm, pm);
 			hpdp = (hugepd_t *)pm;
 		}
 	}
-- 
2.22.0