Re: [PATCH] kmemleak: add oom=<disable|ignore> runtime parameter

[Shu Wang]

Hi

please ignore this patch, I'll upload another one.

Thanks

----- Original Message -----
> From: shuwang@xxxxxxxxxx
> To: "catalin marinas" <catalin.marinas@xxxxxxx>, corbet@xxxxxxx
> Cc: linux-doc@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx, liwang@xxxxxxxxxx,
> shuwang@xxxxxxxxxx, chuhu@xxxxxxxxxx
> Sent: Friday, July 14, 2017 5:39:20 PM
> Subject: [PATCH] kmemleak: add oom=<disable|ignore> runtime parameter
> 
> From: Shu Wang <shuwang@xxxxxxxxxx>
> 
> When running memory stress tests, kmemleak could be easily disabled in
> function create_object as system is out of memory and kmemleak failed to
> alloc from object_cache. Since there's no way to enable kmemleak after
> it's off, simply ignore the object_cache alloc failure will just loses
> track of some memory objects, but could increase the usability of kmemleak
> under memory stress.
> 
> The default action for oom is still disable kmemleak,
> echo oom=ignore > /sys/kernel/debug/kmemleak can change to action to
> ignore oom.
> 
> Signed-off-by: Shu Wang <shuwang@xxxxxxxxxx>
> ---
>  Documentation/dev-tools/kmemleak.rst |  5 +++++
>  mm/kmemleak.c                        | 10 +++++++++-
>  2 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/dev-tools/kmemleak.rst
> b/Documentation/dev-tools/kmemleak.rst
> index cb88626..3013809 100644
> --- a/Documentation/dev-tools/kmemleak.rst
> +++ b/Documentation/dev-tools/kmemleak.rst
> @@ -60,6 +60,11 @@ Memory scanning parameters can be modified at run-time by
> writing to the
>      or free all kmemleak objects if kmemleak has been disabled.
>  - dump=<addr>
>      dump information about the object found at <addr>
> +- oom=disable
> +    disable kmemleak after system out of memory (default)
> +- oom=ignore
> +    do not disable kmemleak after system out of memory
> +    (useful for memory stress test, but will lose some objects)
>  
>  Kmemleak can also be disabled at boot-time by passing ``kmemleak=off`` on
>  the kernel command line.
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 7780cd8..a58080f 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -236,6 +236,9 @@ static DEFINE_MUTEX(scan_mutex);
>  static int kmemleak_skip_disable;
>  /* If there are leaks that can be reported */
>  static bool kmemleak_found_leaks;
> +/* If disable kmemleak after out of memory */
> +static bool kmemleak_oom_disable = true;
> +
>  
>  /*
>   * Early object allocation/freeing logging. Kmemleak is initialized after
>   the
> @@ -556,7 +559,8 @@ static struct kmemleak_object *create_object(unsigned
> long ptr, size_t size,
>  	object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
>  	if (!object) {
>  		pr_warn("Cannot allocate a kmemleak_object structure\n");
> -		kmemleak_disable();
> +		if (kmemleak_oom_disable)
> +			kmemleak_disable();
>  		return NULL;
>  	}
>  
> @@ -1888,6 +1892,10 @@ static ssize_t kmemleak_write(struct file *file, const
> char __user *user_buf,
>  		kmemleak_scan();
>  	else if (strncmp(buf, "dump=", 5) == 0)
>  		ret = dump_str_object_info(buf + 5);
> +	else if (strncmp(buf, "oom=ignore", 10))
> +		kmemleak_oom_disable = false;
> +	else if (strncmp(buf, "oom=disable", 11))
> +		kmemleak_oom_disable = true;
>  	else
>  		ret = -EINVAL;
>  
> --
> 2.5.0
> 
>