[PATCHv2] mm: use stack_depot_early_init for kmemleak
From: zhaoyang.huang
Date: Tue Jan 17 2023 - 03:12:38 EST
From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
Mirsad report bellow error which caused by stack_depot_init failed in kvcalloc.
Solve this by having stackdepot use stack_depot_early_init. Extra Kconfig also
done by moving kmemleak stuff to mm/Kconfig.debug.
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.
reported-by: Mirsad Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
---
v2: use stack_depot_want_early_init instead of CONFIG_STACKDEPOT_ALWAYS_INIT
---
---
lib/Kconfig.debug | 70 -------------------------------------------------------
mm/Kconfig.debug | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
mm/kmemleak.c | 4 +++-
3 files changed, 73 insertions(+), 71 deletions(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 401ad4b..62884ac 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -716,76 +716,6 @@ config SHRINKER_DEBUG
visibility into the kernel memory shrinkers subsystem.
Disable it to avoid an extra memory footprint.
-config HAVE_DEBUG_KMEMLEAK
- bool
-
-config DEBUG_KMEMLEAK
- bool "Kernel memory leak detector"
- depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
- select DEBUG_FS
- select STACKTRACE if STACKTRACE_SUPPORT
- select KALLSYMS
- select CRC32
- select STACKDEPOT
- help
- Say Y here if you want to enable the memory leak
- detector. The memory allocation/freeing is traced in a way
- similar to the Boehm's conservative garbage collector, the
- difference being that the orphan objects are not freed but
- only shown in /sys/kernel/debug/kmemleak. Enabling this
- feature will introduce an overhead to memory
- allocations. See Documentation/dev-tools/kmemleak.rst for more
- details.
-
- Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
- of finding leaks due to the slab objects poisoning.
-
- In order to access the kmemleak file, debugfs needs to be
- mounted (usually at /sys/kernel/debug).
-
-config DEBUG_KMEMLEAK_MEM_POOL_SIZE
- int "Kmemleak memory pool size"
- depends on DEBUG_KMEMLEAK
- range 200 1000000
- default 16000
- help
- Kmemleak must track all the memory allocations to avoid
- reporting false positives. Since memory may be allocated or
- freed before kmemleak is fully initialised, use a static pool
- of metadata objects to track such callbacks. After kmemleak is
- fully initialised, this memory pool acts as an emergency one
- if slab allocations fail.
-
-config DEBUG_KMEMLEAK_TEST
- tristate "Simple test for the kernel memory leak detector"
- depends on DEBUG_KMEMLEAK && m
- help
- This option enables a module that explicitly leaks memory.
-
- If unsure, say N.
-
-config DEBUG_KMEMLEAK_DEFAULT_OFF
- bool "Default kmemleak to off"
- depends on DEBUG_KMEMLEAK
- help
- Say Y here to disable kmemleak by default. It can then be enabled
- on the command line via kmemleak=on.
-
-config DEBUG_KMEMLEAK_AUTO_SCAN
- bool "Enable kmemleak auto scan thread on boot up"
- default y
- depends on DEBUG_KMEMLEAK
- help
- Depending on the cpu, kmemleak scan may be cpu intensive and can
- stall user tasks at times. This option enables/disables automatic
- kmemleak scan at boot up.
-
- Say N here to disable kmemleak auto scan thread to stop automatic
- scanning. Disabling this option disables automatic reporting of
- memory leaks.
-
- If unsure, say Y.
-
config DEBUG_STACK_USAGE
bool "Stack utilization instrumentation"
depends on DEBUG_KERNEL && !IA64
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index ce8dded..d1893ac 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -207,3 +207,73 @@ config PTDUMP_DEBUGFS
kernel.
If in doubt, say N.
+
+config HAVE_DEBUG_KMEMLEAK
+ bool
+
+config DEBUG_KMEMLEAK
+ bool "Kernel memory leak detector"
+ depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
+ select DEBUG_FS
+ select STACKTRACE if STACKTRACE_SUPPORT
+ select KALLSYMS
+ select CRC32
+ select STACKDEPOT
+ help
+ Say Y here if you want to enable the memory leak
+ detector. The memory allocation/freeing is traced in a way
+ similar to the Boehm's conservative garbage collector, the
+ difference being that the orphan objects are not freed but
+ only shown in /sys/kernel/debug/kmemleak. Enabling this
+ feature will introduce an overhead to memory
+ allocations. See Documentation/dev-tools/kmemleak.rst for more
+ details.
+
+ Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
+ of finding leaks due to the slab objects poisoning.
+
+ In order to access the kmemleak file, debugfs needs to be
+ mounted (usually at /sys/kernel/debug).
+
+config DEBUG_KMEMLEAK_MEM_POOL_SIZE
+ int "Kmemleak memory pool size"
+ depends on DEBUG_KMEMLEAK
+ range 200 1000000
+ default 16000
+ help
+ Kmemleak must track all the memory allocations to avoid
+ reporting false positives. Since memory may be allocated or
+ freed before kmemleak is fully initialised, use a static pool
+ of metadata objects to track such callbacks. After kmemleak is
+ fully initialised, this memory pool acts as an emergency one
+ if slab allocations fail.
+
+config DEBUG_KMEMLEAK_TEST
+ tristate "Simple test for the kernel memory leak detector"
+ depends on DEBUG_KMEMLEAK && m
+ help
+ This option enables a module that explicitly leaks memory.
+
+ If unsure, say N.
+
+config DEBUG_KMEMLEAK_DEFAULT_OFF
+ bool "Default kmemleak to off"
+ depends on DEBUG_KMEMLEAK
+ help
+ Say Y here to disable kmemleak by default. It can then be enabled
+ on the command line via kmemleak=on.
+
+config DEBUG_KMEMLEAK_AUTO_SCAN
+ bool "Enable kmemleak auto scan thread on boot up"
+ default y
+ depends on DEBUG_KMEMLEAK
+ help
+ Depending on the cpu, kmemleak scan may be cpu intensive and can
+ stall user tasks at times. This option enables/disables automatic
+ kmemleak scan at boot up.
+
+ Say N here to disable kmemleak auto scan thread to stop automatic
+ scanning. Disabling this option disables automatic reporting of
+ memory leaks.
+
+ If unsure, say Y.
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 762b91f..ddc1ddf 100644
--- a/mm/kmemleak.c
+++ b/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;
--
1.9.1