memblock: exclude MEMBLOCK_NOMAP regions from kmemleak

Vladimir Zapolskiy reports:

Commit a7259df ("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

The memory allocated from memblock is registered with kmemleak, but if
it is marked MEMBLOCK_NOMAP it won't have linear map entries so an
attempt to scan such areas will fault.

Ideally, memblock_mark_nomap() would inform kmemleak to ignore
MEMBLOCK_NOMAP memory, but it can be called before kmemleak interfaces
operating on physical addresses can use __va() conversion.

Make sure that functions that mark allocated memory as MEMBLOCK_NOMAP
take care of informing kmemleak to ignore such memory.

Link: https://lore.kernel.org/all/[email protected]
Link: https://lore.kernel.org/all/[email protected]
Fixes: a7259df ("memblock: make memblock_find_in_range method private")
Reported-by: Vladimir Zapolskiy <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
Reviewed-by: Catalin Marinas <[email protected]>
Tested-by: Vladimir Zapolskiy <[email protected]>
Tested-by: Qian Cai <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: rppt

drivers/acpi/tables.c

@@ -21,6 +21,7 @@
 #include <linux/earlycpio.h>
 #include <linux/initrd.h>
 #include <linux/security.h>
+#include <linux/kmemleak.h>
 #include "internal.h"
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -601,6 +602,8 @@ void __init acpi_table_upgrade(void)
 	 */
 	arch_reserve_mem_area(acpi_tables_addr, all_tables_size);
 
+	kmemleak_ignore_phys(acpi_tables_addr);
+
 	/*
 	 * early_ioremap only can remap 256k one time. If we map all
 	 * tables one time, we will hit the limit. Need to map chunks

drivers/of/of_reserved_mem.c

@@ -21,6 +21,7 @@
 #include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/memblock.h>
+#include <linux/kmemleak.h>
 
 #include "of_private.h"
 
@@ -46,6 +47,7 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
 		err = memblock_mark_nomap(base, size);
 		if (err)
 			memblock_free(base, size);
+		kmemleak_ignore_phys(base);
 	}
 
 	return err;

mm/memblock.c

@@ -932,6 +932,9 @@ int __init_memblock memblock_mark_mirror(phys_addr_t base, phys_addr_t size)
  * covered by the memory map. The struct page representing NOMAP memory
  * frames in the memory map will be PageReserved()
  *
+ * Note: if the memory being marked %MEMBLOCK_NOMAP was allocated from
+ * memblock, the caller must inform kmemleak to ignore that memory
+ *
  * Return: 0 on success, -errno on failure.
  */
 int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)