[PATCH v2 2/2] memblock: exclude MEMBLOCK_NOMAP regions from kmemleak

[Mike Rapoport]

From: Mike Rapoport <rppt@xxxxxxxxxxxxx>

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

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/8ade5174-b143-d621-8c8e-dc6a1898c6fb@xxxxxxxxxx
Link: https://lore.kernel.org/all/c30ff0a2-d196-c50d-22f0-bd50696b1205@xxxxxxxxxxx
Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private")
Reported-by: Vladimir Zapolskiy <vladimir.zapolskiy@xxxxxxxxxx>
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
---
 drivers/acpi/tables.c        | 3 +++
 drivers/of/of_reserved_mem.c | 2 ++
 mm/memblock.c                | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index f9383736fa0f..71419eb16e09 100644
--- a/drivers/acpi/tables.c
+++ b/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
diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 59c1390cdf42..9da8835ba5a5 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/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;
diff --git a/mm/memblock.c b/mm/memblock.c
index 184dcd2e5d99..dab804b09d62 100644
--- a/mm/memblock.c
+++ b/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)
-- 
2.28.0