Subject: [PATCH AUTOSEL 4.19 062/101] powerpc/mm: Handle page table allocation failures

From: Sasha Levin <[email-masked]>
Date: Fri, 19 Jul 2019 00:06:53 -0400

From: "Aneesh Kumar K.V" <[email-masked]>

[ Upstream 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 <[email-masked]>
Signed-off-by: Michael Ellerman <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 arch/powerpc/mm/hugetlbpage.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 7296a42eb62e..cef0b7ee1024 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -150,6 +150,8 @@ 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) {
@@ -158,6 +160,8 @@ 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;
@@ -174,12 +178,16 @@ 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 >= PUD_SHIFT) {
 			ptl = pud_lockptr(mm, pu);
 			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;
 		}
-- 
2.20.1