Re: [PATCH 08/10] cgroups: Pull up res counter charge failureinterpretation to caller

[Kirill A. Shutemov]

On Mon, Oct 03, 2011 at 09:07:10PM +0200, Frederic Weisbecker wrote:
> res_counter_charge() always returns -ENOMEM when the limit is reached
> and the charge thus can't happen.
> 
> However it's up to the caller to interpret this failure and return
> the appropriate error value. The task counter subsystem will need
> to report the user that a fork() has been cancelled because of some
> limit reached, not because we are too short on memory.
> 
> Fix this by returning -1 when res_counter_charge() fails.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>

Acked-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>

> Cc: Paul Menage <paul@xxxxxxxxxxxxxx>
> Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Aditya Kali <adityakali@xxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Kay Sievers <kay.sievers@xxxxxxxx>
> Cc: Tim Hockin <thockin@xxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
> Cc: Containers <containers@xxxxxxxxxxxxxxxxxxxxxxxxxx>
> ---
>  Documentation/cgroups/resource_counter.txt |    2 ++
>  kernel/res_counter.c                       |    2 +-
>  2 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
> index a2cd05b..24ec61c 100644
> --- a/Documentation/cgroups/resource_counter.txt
> +++ b/Documentation/cgroups/resource_counter.txt
> @@ -76,6 +76,8 @@ to work with it.
>  	limit_fail_at parameter is set to the particular res_counter element
>  	where the charging failed.
>  
> +	It returns 0 on success and -1 on failure.
> +
>   d. int res_counter_charge_locked
>  			(struct res_counter *rc, unsigned long val)
>  
> diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> index 6b36823..b814d6c 100644
> --- a/kernel/res_counter.c
> +++ b/kernel/res_counter.c
> @@ -26,7 +26,7 @@ int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
>  {
>  	if (counter->usage + val > counter->limit) {
>  		counter->failcnt++;
> -		return -ENOMEM;
> +		return -1;
>  	}
>  
>  	counter->usage += val;
> -- 
> 1.7.5.4
> 

-- 
 Kirill A. Shutemov
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