Currently this reporting seems not very impressive and not giving much
useful information :
kmemleak: Early log buffer exceeded
kmemleak: Kernel memory leak detector disabled
It should be something like this because it is an error and this will
disable Kernel memory leak detector :
[ 0.000173] ------------[ cut here ]------------
[ 0.000186] WARNING: at mm/kmemleak.c:726 log_early+0x39/0xa9()
[ 0.000189] Hardware name:
[ 0.000192] Early log buffer exceeded, please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE
[ 0.000195] Modules linked in:
[ 0.000202] Pid: 0, comm: swapper Not tainted 2.6.31-rc3 #51
[ 0.000206] Call Trace:
[ 0.000216] [<c102cf74>] warn_slowpath_common+0x60/0x90
[ 0.000222] [<c102cfd8>] warn_slowpath_fmt+0x24/0x27
[ 0.000227] [<c109614b>] log_early+0x39/0xa9
[ 0.000232] [<c109682d>] kmemleak_alloc+0x41/0x4c
[ 0.000241] [<c1093b63>] __kmalloc+0xcb/0x153
[ 0.000247] [<c1093c04>] alloc_arraycache+0x19/0x50
[ 0.000253] [<c1093e44>] do_tune_cpucache+0x209/0x35d
[ 0.000259] [<c10940ee>] enable_cpucache+0x58/0x9a
[ 0.000267] [<c14bc6e5>] kmem_cache_init_late+0x21/0xc2
[ 0.000274] [<c14a8a20>] start_kernel+0x1e5/0x2ba
[ 0.000280] [<c14a8340>] i386_start_kernel+0x6a/0x6f
[ 0.000380] ---[ end trace 4eaa2a86a8e2da22 ]---
[ 0.000384] kmemleak: Kernel memory leak detector disabled
Currently default value of DEBUG_KMEMLEAK_EARLY_LOG_SIZE is 400 which
can be easily exceed-able if debugging is on.
These issues can be fixed like this :
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 12327b2..2eaf8bc 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -362,14 +362,15 @@ config DEBUG_KMEMLEAK
config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
int "Maximum kmemleak early log entries"
depends on DEBUG_KMEMLEAK
- range 200 2000
- default 400
+ range 256 2048
+ default 512
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.
+ used to store these actions. You need to increase this value,
+ if kmemleak reports "Early log buffer exceeded, please increase
+ DEBUG_KMEMLEAK_EARLY_LOG_SIZE".
config DEBUG_KMEMLEAK_TEST
tristate "Simple test for the kernel memory leak detector"
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 5aabd41..084e927 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -722,7 +722,8 @@ 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)) {
- pr_warning("Early log buffer exceeded\n");
+ WARN_ONCE(1, KERN_ERR "Early log buffer exceeded, "
+ "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
kmemleak_disable();
return;
}
--
JSR
On Wed, 2009-07-15 at 22:47 +0530, Jaswinder Singh Rajput wrote:
> Currently this reporting seems not very impressive and not giving much
> useful information :
>
> kmemleak: Early log buffer exceeded
> kmemleak: Kernel memory leak detector disabled
>
> It should be something like this because it is an error and this will
> disable Kernel memory leak detector :
>
> [ 0.000173] ------------[ cut here ]------------
> [ 0.000186] WARNING: at mm/kmemleak.c:726 log_early+0x39/0xa9()
> [ 0.000189] Hardware name:
> [ 0.000192] Early log buffer exceeded, please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE
> [ 0.000195] Modules linked in:
> [ 0.000202] Pid: 0, comm: swapper Not tainted 2.6.31-rc3 #51
> [ 0.000206] Call Trace:
> [ 0.000216] [<c102cf74>] warn_slowpath_common+0x60/0x90
> [ 0.000222] [<c102cfd8>] warn_slowpath_fmt+0x24/0x27
> [ 0.000227] [<c109614b>] log_early+0x39/0xa9
> [ 0.000232] [<c109682d>] kmemleak_alloc+0x41/0x4c
> [ 0.000241] [<c1093b63>] __kmalloc+0xcb/0x153
> [ 0.000247] [<c1093c04>] alloc_arraycache+0x19/0x50
> [ 0.000253] [<c1093e44>] do_tune_cpucache+0x209/0x35d
> [ 0.000259] [<c10940ee>] enable_cpucache+0x58/0x9a
> [ 0.000267] [<c14bc6e5>] kmem_cache_init_late+0x21/0xc2
> [ 0.000274] [<c14a8a20>] start_kernel+0x1e5/0x2ba
> [ 0.000280] [<c14a8340>] i386_start_kernel+0x6a/0x6f
> [ 0.000380] ---[ end trace 4eaa2a86a8e2da22 ]---
> [ 0.000384] kmemleak: Kernel memory leak detector disabled
I'm OK with mentioning DEBUG_KMEMLEAK_EARLY_LOG_SIZE but the stack trace
is not relevant here, it can happen in any place which allocates some
memory.
> Currently default value of DEBUG_KMEMLEAK_EARLY_LOG_SIZE is 400 which
> can be easily exceed-able if debugging is on.
That's why I made it configurable. We can indeed set it to a higher
value but that's after 2.6.31. I have a patch in to mark this buffer as
__initdata so that it is freed.
> These issues can be fixed like this :
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 12327b2..2eaf8bc 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -362,14 +362,15 @@ config DEBUG_KMEMLEAK
> config DEBUG_KMEMLEAK_EARLY_LOG_SIZE
> int "Maximum kmemleak early log entries"
> depends on DEBUG_KMEMLEAK
> - range 200 2000
> - default 400
> + range 256 2048
> + default 512
The power of 2 boundaries is not relevant as this represents the number
of elements in an array rather than a size in bytes.
> 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.
> + used to store these actions. You need to increase this value,
> + if kmemleak reports "Early log buffer exceeded, please increase
> + DEBUG_KMEMLEAK_EARLY_LOG_SIZE".
>
> config DEBUG_KMEMLEAK_TEST
> tristate "Simple test for the kernel memory leak detector"
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 5aabd41..084e927 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -722,7 +722,8 @@ 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)) {
> - pr_warning("Early log buffer exceeded\n");
> + WARN_ONCE(1, KERN_ERR "Early log buffer exceeded, "
> + "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
> kmemleak_disable();
> return;
> }
As I said above, I wouldn't want a stack trace here. Initially, this
code called kmemleak_panic() but changed it since the stack trace isn't
relevant.
Thanks.
--
Catalin