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Date:   Tue, 12 Mar 2019 08:25:41 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Michal Hocko <mhocko@kernel.org>
Cc:     Suren Baghdasaryan <surenb@google.com>,
        Sultan Alsawaf <sultan@kerneltoast.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arve =?iso-8859-1?B?SGr4bm5lduVn?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <christian@brauner.io>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>, devel@driverdev.osuosl.org,
        linux-mm <linux-mm@kvack.org>, Tim Murray <timmurray@google.com>
Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android
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On Tue, Mar 12, 2019 at 09:05:32AM +0100, Michal Hocko wrote:
> On Mon 11-03-19 15:15:35, Suren Baghdasaryan wrote:
> > Yeah, killing speed is a well-known problem which we are considering
> > in LMKD. For example the recent LMKD change to assign process being
> > killed to a cpuset cgroup containing big cores cuts the kill time
> > considerably. This is not ideal and we are thinking about better ways
> > to expedite the cleanup process.
> 
> If you design is relies on the speed of killing then it is fundamentally
> flawed AFAICT. You cannot assume anything about how quickly a task dies.
> It might be blocked in an uninterruptible sleep or performin an
> operation which takes some time. Sure, oom_reaper might help here but
> still.

Many UNINTERRUPTIBLE sleeps can be converted to KILLABLE sleeps.  It just
needs someone to do the work.