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Commit a9d9058a authored by Catalin Marinas's avatar Catalin Marinas
Browse files

kmemleak: Allow the early log buffer to be configurable. 



(feature suggested by Sergey Senozhatsky)

Kmemleak needs to track all the memory allocations but some of these
happen before kmemleak is initialised. These are stored in an internal
buffer which may be exceeded in some kernel configurations. This patch
adds a configuration option with a default value of 400 and also removes
the stack dump when the early log buffer is exceeded.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarSergey Senozhatsky <sergey.senozhatsky@mail.by>
parent 28d0325c

Documentation/kmemleak.txt

+4 −0
Original line number Diff line number Diff line
@@ -41,6 +41,10 @@ Memory scanning parameters can be modified at run-time by writing to the 
Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on

the kernel command line.



Memory may be allocated or freed before kmemleak is initialised and

these actions are stored in an early log buffer. The size of this buffer

is configured via the CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE option.



Basic Algorithm

---------------

lib/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -359,6 +359,18 @@ config DEBUG_KMEMLEAK 
	  In order to access the kmemleak file, debugfs needs to be

	  mounted (usually at /sys/kernel/debug).



config DEBUG_KMEMLEAK_EARLY_LOG_SIZE

	int "Maximum kmemleak early log entries"

	depends on DEBUG_KMEMLEAK

	range 200 2000

	default 400

	help

	  Kmemleak must track all the memory allocations to avoid

	  reporting false positives. Since memory may be allocated or

	  freed before kmemleak is initialised, an early log buffer is

	  used to store these actions. If kmemleak reports "early log

	  buffer exceeded", please increase this value.



config DEBUG_KMEMLEAK_TEST

	tristate "Simple test for the kernel memory leak detector"

	depends on DEBUG_KMEMLEAK

mm/kmemleak.c

+3 −2
Original line number Diff line number Diff line
@@ -235,7 +235,7 @@ struct early_log { 
};



/* early logging buffer and current position */

static struct early_log early_log[200];

static struct early_log early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE];

static int crt_early_log;



static void kmemleak_disable(void);
@@ -696,7 +696,8 @@ static void log_early(int op_type, const void *ptr, size_t size, 
	struct early_log *log;



	if (crt_early_log >= ARRAY_SIZE(early_log)) {

		kmemleak_stop("Early log buffer exceeded\n");

		pr_warning("Early log buffer exceeded\n");

		kmemleak_disable();

		return;

	}