linux-kernel - [PATCH] mm/hugetlb: Initialize page to NULL in alloc_buddy_huge_page_with

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Date:   Tue, 10 Aug 2021 13:06:32 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     feng.tang@...el.com
Cc:     aarcange@...hat.com, ak@...ux.intel.com, akpm@...ux-foundation.org,
        ben.widawsky@...el.com, dan.j.williams@...el.com,
        dave.hansen@...el.com, linux-api@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        mgorman@...hsingularity.net, mhocko@...e.com,
        mike.kravetz@...cle.com, rdunlap@...radead.org,
        rientjes@...gle.com, vbabka@...e.cz, ying.huang@...el.com,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH] mm/hugetlb: Initialize page to NULL in alloc_buddy_huge_page_with_mpol()

Clang warns:

mm/hugetlb.c:2162:6: warning: variable 'page' is used uninitialized
whenever 'if' condition is false [-Wsometimes-uninitialized]
        if (mpol_is_preferred_many(mpol)) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/hugetlb.c:2172:7: note: uninitialized use occurs here
        if (!page)
             ^~~~
mm/hugetlb.c:2162:2: note: remove the 'if' if its condition is always
true
        if (mpol_is_preferred_many(mpol)) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/hugetlb.c:2155:19: note: initialize the variable 'page' to silence
this warning
        struct page *page;
                         ^
                          = NULL
1 warning generated.

Initialize page to NULL like in dequeue_huge_page_vma() so that page is
not used uninitialized.

Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---
 mm/hugetlb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3d9cd2722ea5..604e2d6bd506 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2152,7 +2152,7 @@ static
 struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
 		struct vm_area_struct *vma, unsigned long addr)
 {
-	struct page *page;
+	struct page *page = NULL;
 	struct mempolicy *mpol;
 	gfp_t gfp_mask = htlb_alloc_mask(h);
 	int nid;

base-commit: 18f73b217b4633e27a61832e1485ce927a8ee5c1
-- 
2.33.0.rc1