linux-kernel - Re: Will the recent memory leak fixes be backported to longterm kernels?

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Date:   Fri, 2 Nov 2018 09:03:55 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Dexuan Cui <decui@...rosoft.com>
Cc:     Roman Gushchin <guro@...com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Tejun Heo <tj@...nel.org>, Rik van Riel <riel@...riel.com>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        "Stable@...r.kernel.org" <Stable@...r.kernel.org>
Subject: Re: Will the recent memory leak fixes be backported to longterm
 kernels?

On Fri 02-11-18 02:45:42, Dexuan Cui wrote:
[...]
> I totally agree. I'm now just wondering if there is any temporary workaround,
> even if that means we have to run the kernel with some features disabled or
> with a suboptimal performance?

One way would be to disable kmem accounting (cgroup.memory=nokmem kernel
option). That would reduce the memory isolation because quite a lot of
memory will not be accounted for but the primary source of in-flight and
hard to reclaim memory will be gone.

Another workaround could be to use force_empty knob we have in v1 and
use it when removing a cgroup. We do not have it in cgroup v2 though.
The file hasn't been added to v2 because we didn't really have any
proper usecase. Working around a bug doesn't sound like a _proper_
usecase but I can imagine workloads that bring a lot of metadata objects
that are not really interesting for later use so something like a
targeted drop_caches...
-- 
Michal Hocko
SUSE Labs