linux-kernel - Re: [PATCH cgroup] cgroup: set the correct return code if hierarchy limits are reached

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YrpO9CUDt8hpUprr@castle>
Date:   Mon, 27 Jun 2022 17:44:36 -0700
From:   Roman Gushchin <roman.gushchin@...ux.dev>
To:     Vasily Averin <vvs@...nvz.org>
Cc:     Shakeel Butt <shakeelb@...gle.com>,
        Michal Koutný <mkoutny@...e.com>,
        Michal Hocko <mhocko@...e.com>, Tejun Heo <tj@...nel.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Johannes Weiner <hannes@...xchg.org>, kernel@...nvz.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Vlastimil Babka <vbabka@...e.cz>,
        Muchun Song <songmuchun@...edance.com>, cgroups@...r.kernel.org
Subject: Re: [PATCH cgroup] cgroup: set the correct return code if hierarchy
 limits are reached

On Mon, Jun 27, 2022 at 05:12:55AM +0300, Vasily Averin wrote:
> When cgroup_mkdir reaches the limits of the cgroup hierarchy, it should
> not return -EAGAIN, but instead react similarly to reaching the global
> limit.
> 
> Signed-off-by: Vasily Averin <vvs@...nvz.org>
> ---
>  kernel/cgroup/cgroup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index 1be0f81fe8e1..243239553ea3 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -5495,7 +5495,7 @@ int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode)
>  		return -ENODEV;
>  
>  	if (!cgroup_check_hierarchy_limits(parent)) {
> -		ret = -EAGAIN;
> +		ret = -ENOSPC;

I'd not argue whether ENOSPC is better or worse here, but I don't think we need
to change it now. It's been in this state for a long time and is a part of ABI.
EAGAIN is pretty unique as a mkdir() result, so systemd can handle it well.

Thanks!