From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chris Down <chris@chrisdown.name>
Subject: Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude
 protection
Date: Wed, 29 May 2019 23:44:53 -0700
Message-ID: <20190530064453.GA110128@chrisdown.name>
References: <20190228213050.GA28211@chrisdown.name>
 <20190322160307.GA3316@chrisdown.name>
 <20190530061221.GA6703@dhcp22.suse.cz>
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To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>, Roman Gushchin <guro@fb.com>, Dennis Zhou <dennis@kernel.org>, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, kernel-team@fb.com

Michal Hocko writes:
>Maybe I am missing something so correct me if I am wrong but the new
>calculation actually means that we always allow to scan even min
>protected memcgs right?

We check if the memcg is min protected as a precondition for coming into this 
function at all, so this generally isn't possible. See the mem_cgroup_protected 
MEMCG_PROT_MIN check in shrink_node.

(Of course, it's possible we race with going within protection thresholds 
again, but this patch doesn't make that any better or worse than the previous 
situation.)