mm: use stack_depot_early_init for kmemleak

Mirsad report the below error which is caused by stack_depot_init()
failure in kvcalloc.  Solve this by having stackdepot use
stack_depot_early_init().

On 1/4/23 17:08, Mirsad Goran Todorovac wrote:
I hate to bring bad news again, but there seems to be a problem with the output of /sys/kernel/debug/kmemleak:

[root@pc-mtodorov ~]# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff951c118568b0 (size 16):
comm "kworker/u12:2", pid 56, jiffies 4294893952 (age 4356.548s)
hex dump (first 16 bytes):
    6d 65 6d 73 74 69 63 6b 30 00 00 00 00 00 00 00 memstick0.......
    backtrace:
[root@pc-mtodorov ~]#

Apparently, backtrace of called functions on the stack is no longer
printed with the list of memory leaks.  This appeared on Lenovo desktop
10TX000VCR, with AlmaLinux 8.7 and BIOS version M22KT49A (11/10/2022) and
6.2-rc1 and 6.2-rc2 builds.  This worked on 6.1 with the same
CONFIG_KMEMLEAK=y and MGLRU enabled on a vanilla mainstream kernel from
Mr.  Torvalds' tree.  I don't know if this is deliberate feature for some
reason or a bug.  Please find attached the config, lshw and kmemleak
output.

[[email protected]: remove stack_depot_init() call]
Link: https://lore.kernel.org/all/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 56a6161 ("mm: use stack_depot for recording kmemleak's backtrace")
Reported-by: Mirsad Todorovac <[email protected]>
Suggested-by: Vlastimil Babka <[email protected]>
Signed-off-by: Zhaoyang Huang <[email protected]>
Acked-by: Mike Rapoport (IBM) <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Tested-by: Borislav Petkov (AMD) <[email protected]>
Cc: ke.wang <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Zhaoyang Huang

lib/Kconfig.debug

@@ -754,6 +754,7 @@ config DEBUG_KMEMLEAK
 	select KALLSYMS
 	select CRC32
 	select STACKDEPOT
+	select STACKDEPOT_ALWAYS_INIT if !DEBUG_KMEMLEAK_DEFAULT_OFF
 	help
 	  Say Y here if you want to enable the memory leak
 	  detector. The memory allocation/freeing is traced in a way

mm/kmemleak.c

@@ -2070,8 +2070,10 @@ static int __init kmemleak_boot_config(char *str)
 		return -EINVAL;
 	if (strcmp(str, "off") == 0)
 		kmemleak_disable();
-	else if (strcmp(str, "on") == 0)
+	else if (strcmp(str, "on") == 0) {
 		kmemleak_skip_disable = 1;
+		stack_depot_want_early_init();
+	}
 	else
 		return -EINVAL;
 	return 0;
@@ -2093,7 +2095,6 @@ void __init kmemleak_init(void)
 	if (kmemleak_error)
 		return;
 
-	stack_depot_init();
 	jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
 	jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);