memblock: exclude NOMAP regions from kmemleak

Vladimir Zapolskiy reports:

commit a7259df767 ("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: a7259df767 ("memblock: make memblock_find_in_range method private")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Tested-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>

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;
 }
 
 /**