linux-kernel - [PATCH v3 3/3] mm: kmemleak: check physical address when scan

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Date:   Thu,  9 Jun 2022 20:49:50 +0800
From:   Patrick Wang <patrick.wang.shcn@...il.com>
To:     catalin.marinas@....com, akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        yee.lee@...iatek.com, patrick.wang.shcn@...il.com
Subject: [PATCH v3 3/3] mm: kmemleak: check physical address when scan

Check the physical address of objects for its boundary
when scan instead of in kmemleak_*_phys().

Fixes: 23c2d497de21 ("mm: kmemleak: take a full lowmem check in kmemleak_*_phys()")
Suggested-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Patrick Wang <patrick.wang.shcn@...il.com>
---
 mm/kmemleak.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 155f50e1a604..387d6fa402c6 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1184,7 +1184,7 @@ void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, gfp_t gfp)
 {
 	pr_debug("%s(0x%pa, %zu)\n", __func__, &phys, size);
 
-	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
+	if (kmemleak_enabled)
 		/*
 		 * Create object with OBJECT_PHYS flag and
 		 * assume min_count 0.
@@ -1204,7 +1204,7 @@ void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
 {
 	pr_debug("%s(0x%pa)\n", __func__, &phys);
 
-	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
+	if (kmemleak_enabled)
 		delete_object_part((unsigned long)phys, size, true);
 }
 EXPORT_SYMBOL(kmemleak_free_part_phys);
@@ -1218,7 +1218,7 @@ void __ref kmemleak_ignore_phys(phys_addr_t phys)
 {
 	pr_debug("%s(0x%pa)\n", __func__, &phys);
 
-	if (PHYS_PFN(phys) >= min_low_pfn && PHYS_PFN(phys) < max_low_pfn)
+	if (kmemleak_enabled)
 		make_black_object((unsigned long)phys, true);
 }
 EXPORT_SYMBOL(kmemleak_ignore_phys);
@@ -1493,6 +1493,17 @@ static void kmemleak_scan(void)
 			dump_object_info(object);
 		}
 #endif
+
+		/* ignore objects outside lowmem (paint them black) */
+		if ((object->flags & OBJECT_PHYS) &&
+		   !(object->flags & OBJECT_NO_SCAN)) {
+			unsigned long phys = object->pointer;
+
+			if (PHYS_PFN(phys) < min_low_pfn ||
+			    PHYS_PFN(phys + object->size) >= max_low_pfn)
+				__paint_it(object, KMEMLEAK_BLACK);
+		}
+
 		/* reset the reference count (whiten the object) */
 		object->count = 0;
 		if (color_gray(object) && get_object(object))
-- 
2.25.1