[PATCH v2] debugobjects: add a new Kconfig for POOL_SIZE

Qian Cai
2018-11-18T22:09:30Z

The current value of ODEBUG_POOL_SIZE is not big enough for systems with
large number of CPUs with timer or/and workqueue objects because during
the early boot, timer objects needs the size equals to

No. CPUs x 2 (worker pool)

start_kernel
workqueue_init_early
init_worker_pool
init_timer_key
debug_object_init

puls, No. CPUs (if have the hrtimer option)

start_kernel
sched_init
hrtick_rq_init
hrtimer_init
debug_object_init

Then, workqueue objects requires even more,

No. CPUs x 6 (workqueue)

start_kernel
workqueue_init_early
alloc_workqueue
__alloc_workqueue_key
alloc_and_link_pwqs
init_pwq
debug_object_init

plus, No, CPUs x 2 (worker pool) (if have the perf option)

start_kernel
perf_event_init
__init_srcu_struct
init_srcu_struct_fields
__init_work
debug_object_init

As the results, systems have 60+ CPUs with both timer and workqueue
objects enabled could trigger "ODEBUG: Out of memory. ODEBUG disabled".

Hence, add a new Kconfig option so users could adjust ODEBUG_POOL_SIZE
accordingly if either timer or workqueue objects are selected.

Signed-off-by: Qian Cai <cai@gmx.us>
---

Changes since v1:
* Fixed a few typos.
* Added missing call stacks.
* Removed implementation details from the Kconfig help.

lib/Kconfig.debug | 11 +++++++++++
lib/debugobjects.c | 4 ++++
2 files changed, 15 insertions(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1af29b8224fd..0749dc627eb5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -449,6 +449,17 @@ config DEBUG_OBJECTS
kernel to track the life time of various objects and validate
the operations on those objects.

+config DEBUG_OBJECTS_POOL_SIZE
+ int "Debug objects pool size"
+ depends on DEBUG_OBJECTS_TIMERS || DEBUG_OBJECTS_WORK
+ default 1024
+ help
+ Some debug objects are allocated during the early boot. Enabling some
+ options below like timers or workqueue objects may increase the size
+ required significantly with large number of CPUs. If the kernel
+ reports "ODEBUG: Out of memory. ODEBUG disabled", please increase
+ this value.
+
config DEBUG_OBJECTS_SELFTEST
bool "Debug objects selftest"
depends on DEBUG_OBJECTS
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 70935ed91125..b0e8e90f6ad1 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -23,7 +23,11 @@
#define ODEBUG_HASH_BITS 14
#define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)

+#ifdef CONFIG_DEBUG_OBJECTS_POOL_SIZE
+#define ODEBUG_POOL_SIZE CONFIG_DEBUG_OBJECTS_POOL_SIZE
+#else
#define ODEBUG_POOL_SIZE 1024
+#endif
#define ODEBUG_POOL_MIN_LEVEL 256

#define ODEBUG_CHUNK_SHIFT PAGE_SHIFT
--
2.17.2 (Apple Git-113)