linux-kernel - [PATCH] mm/debug: Fix minor issues in mm

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Message-Id: <20250312011236.262766-1-liuye@kylinos.cn>
Date: Wed, 12 Mar 2025 09:12:36 +0800
From: Liu Ye <liuye@...inos.cn>
To: akpm@...ux-foundation.org
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Liu Ye <liuye@...inos.cn>
Subject: [PATCH] mm/debug: Fix minor issues in mm

This patch includes several minor fixes:

- Fix out-of-bounds access in page_type_name().
- Simplify compound page judgment conditions.
- Missing a newline character at the end of the format string.

Each change is independent.

Signed-off-by: Liu Ye <liuye@...inos.cn>
---
 mm/debug.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/debug.c b/mm/debug.c
index 8d2acf432385..9a3092e65765 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -62,7 +62,7 @@ static const char *page_type_name(unsigned int page_type)
 {
 	unsigned i = (page_type >> 24) - 0xf0;
 
-	if (i >= ARRAY_SIZE(page_type_names))
+	if (i < 0 || i >= ARRAY_SIZE(page_type_names))
 		return "unknown";
 	return page_type_names[i];
 }
@@ -132,15 +132,15 @@ static void __dump_page(const struct page *page)
 again:
 	memcpy(&precise, page, sizeof(*page));
 	head = precise.compound_head;
-	if ((head & 1) == 0) {
+	if (head & 1) {
+		foliop = (struct folio *)(head - 1);
+		idx = folio_page_idx(foliop, page);
+	} else {
 		foliop = (struct folio *)&precise;
 		idx = 0;
 		if (!folio_test_large(foliop))
 			goto dump;
 		foliop = (struct folio *)page;
-	} else {
-		foliop = (struct folio *)(head - 1);
-		idx = folio_page_idx(foliop, page);
 	}
 
 	if (idx < MAX_FOLIO_NR_PAGES) {
@@ -165,7 +165,7 @@ static void __dump_page(const struct page *page)
 void dump_page(const struct page *page, const char *reason)
 {
 	if (PagePoisoned(page))
-		pr_warn("page:%p is uninitialized and poisoned", page);
+		pr_warn("page:%p is uninitialized and poisoned\n", page);
 	else
 		__dump_page(page);
 	if (reason)
-- 
2.25.1