linux-kernel - Re: [RFC PATCH] mm, oom: introduce vm.sacrifice_hugepage_on

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Message-ID: <YC0OjfaiFzRUJOx4@dhcp22.suse.cz>
Date:   Wed, 17 Feb 2021 13:40:36 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Eiichi Tsukata <eiichi.tsukata@...anix.com>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>,
        "corbet@....net" <corbet@....net>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "yzaikin@...gle.com" <yzaikin@...gle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        Felipe Franciosi <felipe@...anix.com>
Subject: Re: [RFC PATCH] mm, oom: introduce vm.sacrifice_hugepage_on_oom

On Wed 17-02-21 13:31:07, Michal Hocko wrote:
[...]
> Thanks for your usecase description. It helped me to understand what you
> are doing and how this can be really useful for your particular setup.
> This is really a very specific situation from my POV. I am not yet sure
> this is generic enough to warrant for a yet another tunable. One thing
> you can do [1] is to
> hook into oom notifiers interface (register_oom_notifier) and release
> pages from the callback.

Forgot to mention that this would be done from a kernel module.

> Why is that batter than a global tunable?
> For one thing you can make the implementation tailored to your specific
> usecase. As the review feedback has shown this would be more tricky to
> be done in a general case. Unlike a generic solution it would allow you
> to coordinate with your userspace if you need. Would something like that
> work for you?
> 
> ---
> [1] and I have to say I hate myself for suggesting that because I was
> really hoping this interface would go away. But the reality disagrees so
> I gave up on that goal...
> -- 
> Michal Hocko
> SUSE Labs

-- 
Michal Hocko
SUSE Labs