From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Michal Hocko <mhocko@kernel.org>
Cc: Lucian Adrian Grijincu <lucian@fb.com>,
linux-mm@kvack.org, Souptick Joarder <jrdr.linux@gmail.com>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@fb.com>, Roman Gushchin <guro@fb.com>
Subject: Re: [PATCH v3] mm: memory: fix /proc/meminfo reporting for MLOCK_ONFAULT
Date: Tue, 17 Sep 2019 14:35:50 +0300 [thread overview]
Message-ID: <20190917113550.v6nool7oizht66fx@box> (raw)
In-Reply-To: <20190917101519.GD1872@dhcp22.suse.cz>
On Tue, Sep 17, 2019 at 12:15:19PM +0200, Michal Hocko wrote:
> On Mon 16-09-19 18:26:19, Kirill A. Shutemov wrote:
> > On Fri, Sep 13, 2019 at 02:11:19PM -0700, Lucian Adrian Grijincu wrote:
> > > As pages are faulted in MLOCK_ONFAULT correctly updates
> > > /proc/self/smaps, but doesn't update /proc/meminfo's Mlocked field.
> >
> > I don't think there's something wrong with this behaviour. It is okay to
> > keep the page an evictable LRU list (and not account it to NR_MLOCKED).
>
> evictable list is an implementation detail. Having an overview about an
s/evictable/unevictable/
> amount of mlocked pages can be important. Lazy accounting makes this
> more fuzzy and harder for admins to monitor.
>
> Sure it is not a bug to panic about but it certainly makes life of poor
> admins harder.
Good luck with making mlock accounting exact :P
For start, try to handle sanely trylock_page() failure under ptl while
dealing with FOLL_MLOCK.
> If there is a pathological THP behavior possible then we should look
> into that as well.
There's nothing pathological about THP behaviour. See "MLOCKING
Transparent Huge Pages" section in Documentation/vm/unevictable-lru.rst.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2019-09-17 11:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-13 21:11 Lucian Adrian Grijincu
2019-09-13 21:17 ` [Potential Spoof] " Roman Gushchin
2019-09-16 11:35 ` Michal Hocko
2019-09-16 21:34 ` Lucian Grijincu
2019-09-16 15:26 ` Kirill A. Shutemov
2019-09-17 10:15 ` Michal Hocko
2019-09-17 11:35 ` Kirill A. Shutemov [this message]
2019-09-23 8:50 ` Michal Hocko
2019-09-17 11:37 ` Kirill A. Shutemov
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