linux-kernel - Re: [PATCH] kmemleak: record accurate early log buffer count and report when exceeded

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Date:	Wed, 15 Apr 2015 16:13:00 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Wang Kai <morgan.wang@...wei.com>
Cc:	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kmemleak: record accurate early log buffer count and
 report when exceeded

(I see you corrected the LKML address; I replied to your early patch)

On Wed, Apr 15, 2015 at 12:49:23PM +0100, Wang Kai wrote:
> In log_early function, crt_early_log should also count once when
> 'crt_early_log >= ARRAY_SIZE(early_log)'. Otherwise the reported
> count from kmemleak_init is one less than 'actual number'.
> 
> Then, in kmemleak_init, if early_log buffer size equal actual
> number, kmemleak will init sucessful, so change warning condition
> to 'crt_early_log > ARRAY_SIZE(early_log)'.
> 
> Signed-off-by: Wang Kai <morgan.wang@...wei.com>
> ---
>  mm/kmemleak.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 5405aff..49956cf 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -814,6 +814,8 @@ static void __init log_early(int op_type, const void *ptr, size_t size,
>  	}
>  
>  	if (crt_early_log >= ARRAY_SIZE(early_log)) {
> +		/* kmemleak will stop recording, just count the requests */

You could say "just count the last request" since kmemleak_disable()
would set kmemleak_error to 1 and you never get to this block again.

> +		crt_early_log++;
>  		kmemleak_disable();
>  		return;
>  	}
> @@ -1829,7 +1831,8 @@ void __init kmemleak_init(void)
>  	object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
>  	scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
>  
> -	if (crt_early_log >= ARRAY_SIZE(early_log))
> +	/* Don't warning when crt_early_log == ARRAY_SIZE(early_log) */

s/warning/warn/

But I don't think this comment is needed, just add it to the commit log.

> +	if (crt_early_log > ARRAY_SIZE(early_log))
>  		pr_warning("Early log buffer exceeded (%d), please increase "
>  			   "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);

Otherwise, my ack still stands:

Acked-by: Catalin Marinas <catalin.marinas@....com>
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