Date:   Thu, 2 Mar 2023 18:41:47 +0100
From:   Michal Hocko <mhocko@suse.com>
To:     Suren Baghdasaryan <surenb@google.com>
Cc:     Johannes Weiner <hannes@cmpxchg.org>, tj@kernel.org,
        lizefan.x@bytedance.com, peterz@infradead.org, johunt@akamai.com,
        keescook@chromium.org, quic_sudaraja@quicinc.com,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] psi: remove 500ms min window size limitation for
 triggers
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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