From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
Subject: Re: [PATCH 1/1] psi: remove 500ms min window size limitation for
 triggers
Date: Thu, 2 Mar 2023 18:41:47 +0100
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To: Suren Baghdasaryan <surenb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, johunt-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org, keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, quic_sudaraja-jfJNa2p1gH1BDgjK7y7TUQ@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

On Thu 02-03-23 08:13:54, Suren Baghdasaryan wrote:
[...]
> Let's roll this check without additional changes and then consolidate
> the checking inside psi_trigger_create() in a separate patch. If
> anybody objects to the late permission check we will just revert that
> last change without affecting anything else.

Permissions checks at write time are problematic because userspace
cannot drop privileges. Also I think it would be an antipattern for how
we do this in general. 
-- 
Michal Hocko
SUSE Labs