linux-kernel - [PATCH] mm/hugetlb.c: check the failure case for find

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Date:   Wed, 24 Jul 2019 20:39:44 -0500
From:   Navid Emamdoost <navid.emamdoost@...il.com>
To:     emamd001@....edu
Cc:     kjlu@....edu, smccaman@....edu,
        Navid Emamdoost <navid.emamdoost@...il.com>,
        Mike Kravetz <mike.kravetz@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm/hugetlb.c: check the failure case for find_vma

find_vma may fail and return NULL. The null check is added.

Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
---
 mm/hugetlb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ede7e7f5d1ab..9c5e8b7a6476 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4743,6 +4743,9 @@ void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
 {
 	struct vm_area_struct *vma = find_vma(mm, addr);
+	if (!vma)
+		return (pte_t *)pmd_alloc(mm, pud, addr);
+
 	struct address_space *mapping = vma->vm_file->f_mapping;
 	pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) +
 			vma->vm_pgoff;
-- 
2.17.1