Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 5 Nov 2018 14:05:44 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Kuo-Hsin Yang <vovoy@chromium.org>
Cc:     linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org,
        linux-mm@kvack.org, Chris Wilson <chris@chris-wilson.co.uk>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH v4] mm, drm/i915: mark pinned shmemfs pages as unevictable
Message-ID: <20181105130544.GJ4361@dhcp22.suse.cz>
References: <20181105111348.182492-1-vovoy@chromium.org>
 <20181105130209.GI4361@dhcp22.suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181105130209.GI4361@dhcp22.suse.cz>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon 05-11-18 14:02:09, Michal Hocko wrote:
> On Mon 05-11-18 19:13:48, Kuo-Hsin Yang wrote:
> > The i915 driver uses shmemfs to allocate backing storage for gem
> > objects. These shmemfs pages can be pinned (increased ref count) by
> > shmem_read_mapping_page_gfp(). When a lot of pages are pinned, vmscan
> > wastes a lot of time scanning these pinned pages. In some extreme case,
> > all pages in the inactive anon lru are pinned, and only the inactive
> > anon lru is scanned due to inactive_ratio, the system cannot swap and
> > invokes the oom-killer. Mark these pinned pages as unevictable to speed
> > up vmscan.
> > 
> > Export pagevec API check_move_unevictable_pages().
> 
> Thanks for reworking the patch. This looks much more to my taste. At
> least the mm part. I haven't really looked at the the drm part.

One side note. Longterm we probably want a better pinning API. It would
hide this LRU manipulation implementation detail + enforce some limiting
and provide a good way that the pin is longterm. People are working on
this already but it is a PITA and long time to get there.
-- 
Michal Hocko
SUSE Labs