[Devel] [PATCH rh7] sched: Fallback to 0-order allocations in sched_create_group()

[Kirill Tkhai]

On 29.12.2017 14:44, Andrey Ryabinin wrote:
> On large machines ->cpustat_last/->vcpustat arrays are large
> causing possibly failing high-order allocation:
> 
>        fio: page allocation failure: order:4, mode:0xc0d0
> 
>        Call Trace:
>          dump_stack+0x19/0x1b
>          warn_alloc_failed+0x110/0x180
>           __alloc_pages_nodemask+0x7bf/0xc60
>          alloc_pages_current+0x98/0x110
>          kmalloc_order+0x18/0x40
>          kmalloc_order_trace+0x26/0xa0
>          __kmalloc+0x279/0x290
>          sched_create_group+0xba/0x150
>          sched_autogroup_create_attach+0x3f/0x1a0
>          sys_setsid+0x73/0xc0
>          system_call_fastpath+0x16/0x1b
> 
> Use kvzalloc to fallback to vmalloc() and avoid failure if
> high order page is not available.
> 
> https://jira.sw.ru/browse/PSBM-79891
> Fixes: 85fd6b2ff490 ("sched: Port cpustat related patches")
> Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>

Acked-by: Kirill Tkhai <ktkhai at virtuozzo.com>

> ---
>  kernel/sched/core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 75ef029b1595..6979f7d8ead7 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -8761,8 +8761,8 @@ static void free_sched_group(struct task_group *tg)
>  	free_rt_sched_group(tg);
>  	autogroup_free(tg);
>  	free_percpu(tg->taskstats);
> -	kfree(tg->cpustat_last);
> -	kfree(tg->vcpustat);
> +	kvfree(tg->cpustat_last);
> +	kvfree(tg->vcpustat);
>  	kfree(tg);
>  }
>  
> @@ -8785,12 +8785,12 @@ struct task_group *sched_create_group(struct task_group *parent)
>  	if (!tg->taskstats)
>  		goto err;
>  
> -	tg->cpustat_last = kcalloc(nr_cpu_ids, sizeof(struct kernel_cpustat),
> +	tg->cpustat_last = kvzalloc(nr_cpu_ids * sizeof(struct kernel_cpustat),
>  				   GFP_KERNEL);
>  	if (!tg->cpustat_last)
>  		goto err;
>  
> -	tg->vcpustat = kcalloc(nr_cpu_ids, sizeof(struct kernel_cpustat),
> +	tg->vcpustat = kvzalloc(nr_cpu_ids * sizeof(struct kernel_cpustat),
>  			       GFP_KERNEL);
>  	if (!tg->vcpustat)
>  		goto err;
>