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Date:   Tue, 16 Oct 2018 20:21:55 +0200
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, akpm@linux-foundation.org,
        chris@chris-wilson.co.uk, peterz@infradead.org,
        dave.hansen@intel.com, corbet@lwn.net, hughd@google.com,
        joonas.lahtinen@linux.intel.com, marcheu@chromium.org,
        hoegsberg@chromium.org
Subject: Re: [PATCH 2/2] drm/i915: Mark pinned shmemfs pages as unevictable
Message-ID: <20181016182155.GW18839@dhcp22.suse.cz>
References: <20181016174300.197906-1-vovoy@chromium.org>
 <20181016174300.197906-3-vovoy@chromium.org>
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On Wed 17-10-18 01:43:00, Kuo-Hsin Yang wrote:
> The i915 driver use 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. Mark these pinned
> pages as unevictable to speed up vmscan.

I would squash the two patches into the single one. One more thing
though. One more thing to be careful about here. Unless I miss something
such a page is not migrateable so it shouldn't be allocated from a
movable zone. Does mapping_gfp_constraint contains __GFP_MOVABLE? If
yes, we want to drop it as well. Other than that the patch makes sense
with my very limited knowlege of the i915 code of course.
-- 
Michal Hocko
SUSE Labs