linux-kernel - [PATCH] memblock: exclude NOMAP regions from kmemleak

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Date:   Wed, 13 Oct 2021 08:47:56 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] memblock: exclude NOMAP regions from kmemleak

From: Mike Rapoport <rppt@...ux.ibm.com>

Vladimir Zapolskiy reports:

commit a7259df76702 ("memblock: make memblock_find_in_range method private")
invokes a kernel panic while running kmemleak on OF platforms with nomaped
regions:

  Unable to handle kernel paging request at virtual address fff000021e00000
  [...]
    scan_block+0x64/0x170
    scan_gray_list+0xe8/0x17c
    kmemleak_scan+0x270/0x514
    kmemleak_write+0x34c/0x4ac

Indeed, NOMAP regions don't have linear map entries so an attempt to scan
these areas would fault.

Prevent such faults by excluding NOMAP regions from kmemleak.

Link: https://lore.kernel.org/all/8ade5174-b143-d621-8c8e-dc6a1898c6fb@linaro.org
Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private")
Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
---
 mm/memblock.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 184dcd2e5d99..5c3503c98b2f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -936,7 +936,12 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
  */
 int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
 {
-	return memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
+	int ret = memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
+
+	if (!ret)
+		kmemleak_free_part_phys(base, size);
+
+	return ret;
 }
 
 /**

base-commit: 64570fbc14f8d7cb3fe3995f20e26bc25ce4b2cc
-- 
2.28.0