linux-kernel - Re: [PATCH] memcg: accounting for objects allocated for new netdevice

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Message-ID: <20220427140153.GC9823@blackbody.suse.cz>
Date:   Wed, 27 Apr 2022 16:01:53 +0200
From:   Michal Koutný <mkoutny@...e.com>
To:     Vasily Averin <vvs@...nvz.org>
Cc:     Roman Gushchin <roman.gushchin@...ux.dev>,
        Vlastimil Babka <vbabka@...e.cz>,
        Shakeel Butt <shakeelb@...gle.com>, kernel@...nvz.org,
        Florian Westphal <fw@...len.de>, linux-kernel@...r.kernel.org,
        Michal Hocko <mhocko@...e.com>, cgroups@...r.kernel.org,
        netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Tejun Heo <tj@...nel.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] memcg: accounting for objects allocated for new netdevice

Hello Vasily.

On Wed, Apr 27, 2022 at 01:37:50PM +0300, Vasily Averin <vvs@...nvz.org> wrote:
> diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
> index cfa79715fc1a..2881aeeaa880 100644
> --- a/fs/kernfs/mount.c
> +++ b/fs/kernfs/mount.c
> @@ -391,7 +391,7 @@ void __init kernfs_init(void)
>  {
>  	kernfs_node_cache = kmem_cache_create("kernfs_node_cache",
>  					      sizeof(struct kernfs_node),
> -					      0, SLAB_PANIC, NULL);
> +					      0, SLAB_PANIC | SLAB_ACCOUNT, NULL);

kernfs accounting you say?
kernfs backs up also cgroups, so the parent-child accounting comes to my
mind.
See the temporary switch to parent memcg in mem_cgroup_css_alloc().

(I mean this makes some sense but I'd suggest unlumping the kernfs into
a separate path for possible discussion and its not-only-netdevice
effects.)

Thanks,
Michal