linux-kernel - Re: [RFC v4 0/3] mm: zap pages with read mmap

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Message-ID: <20180711111311.hrh5kxdottmpdpn2@kshutemo-mobl1>
Date:   Wed, 11 Jul 2018 14:13:12 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Yang Shi <yang.shi@...ux.alibaba.com>, willy@...radead.org,
        ldufour@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC v4 0/3] mm: zap pages with read mmap_sem in munmap for
 large mapping

On Wed, Jul 11, 2018 at 12:33:12PM +0200, Michal Hocko wrote:
> this is not a small change for something that could be achieved
> from the userspace trivially (just call madvise before munmap - library
> can hide this). Most workloads will even not care about races because
> they simply do not play tricks with mmaps and userspace MM. So why do we
> want to put the additional complexity into the kernel?

As I said before, kernel latency issues have to be addressed in kernel.
We cannot rely on userspace being kind here.

-- 
 Kirill A. Shutemov