[Devel] [PATCH VZ9 3/3] mm/memcontrol: make memory.oom_guarantee file also available in cgroup-v2

[Pavel Tikhomirov]

On 22/03/2024 13:21, Pavel Tikhomirov wrote:
> The interface is slightly reworked to be more v2 like:
> 
> - show "max" when uninitialized and allow to write it

Slightly bad wording, it is 0 when uninitialized. Should be:

- show "max" when has max value and allow to write it

> 
> https://virtuozzo.atlassian.net/browse/PSBM-154224
> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
> 
> Feature: mm/oom: OOM guarantee feature
> ---
>   mm/memcontrol.c | 30 ++++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index fcc4b24ba330..f709ed6be891 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5239,6 +5239,14 @@ static u64 mem_cgroup_oom_guarantee_read(struct cgroup_subsys_state *css,
>   	return mem_cgroup_from_css(css)->oom_guarantee << PAGE_SHIFT;
>   }
>   
> +static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value);
> +
> +static int memory_oom_guarantee_show(struct seq_file *m, void *v)
> +{
> +	return seq_puts_memcg_tunable(m,
> +		READ_ONCE(mem_cgroup_from_seq(m)->oom_guarantee));
> +}
> +
>   static ssize_t mem_cgroup_oom_guarantee_write(struct kernfs_open_file *kops,
>   					char *buffer, size_t nbytes, loff_t off)
>   {
> @@ -5255,6 +5263,22 @@ static ssize_t mem_cgroup_oom_guarantee_write(struct kernfs_open_file *kops,
>   	return nbytes;
>   }
>   
> +static ssize_t memory_oom_guarantee_write(struct kernfs_open_file *of,
> +					  char *buf, size_t nbytes, loff_t off)
> +{
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
> +	unsigned long oom_guarantee;
> +	int err;
> +
> +	buf = strstrip(buf);
> +	err = page_counter_memparse(buf, "max", &oom_guarantee);
> +	if (err)
> +		return err;
> +
> +	memcg->oom_guarantee = oom_guarantee;
> +	return nbytes;
> +}
> +
>   #ifdef CONFIG_CLEANCACHE
>   static u64 mem_cgroup_disable_cleancache_read(struct cgroup_subsys_state *css,
>   					      struct cftype *cft)
> @@ -7629,6 +7653,12 @@ static struct cftype memory_files[] = {
>   		.flags = CFTYPE_NS_DELEGATABLE,
>   		.write = memory_reclaim,
>   	},
> +	{
> +		.name = "oom_guarantee",
> +		.flags = CFTYPE_NOT_ON_ROOT,
> +		.seq_show = memory_oom_guarantee_show,
> +		.write = memory_oom_guarantee_write,
> +	},
>   	{ }	/* terminate */
>   };
>   

-- 
Best regards, Tikhomirov Pavel
Senior Software Developer, Virtuozzo.