linux-kernel - Re: [PATCH] drm: use kvmalloc_array for drm

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Message-ID: <20170516105352.GH2481@dhcp22.suse.cz>
Date:   Tue, 16 May 2017 12:53:52 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>
Subject: Re: [PATCH] drm: use kvmalloc_array for drm_malloc*

On Tue 16-05-17 10:31:19, Chris Wilson wrote:
> On Tue, May 16, 2017 at 11:06:06AM +0200, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@...e.com>
> > 
> > drm_malloc* has grown their own kmalloc with vmalloc fallback
> > implementations. MM has grown kvmalloc* helpers in the meantime. Let's
> > use those because it a) reduces the code and b) MM has a better idea
> > how to implement fallbacks (e.g. do not vmalloc before kmalloc is tried
> > with __GFP_NORETRY).
> 
> Better? The same idea. The only difference I was reluctant to hand out
> large pages for long lived objects. If that's the wisdom of the core mm,
> so be it.

vmalloc tends to fragment physical memory more os it is preferable to
try the physically contiguous request first and only fall back to
vmalloc if the first attempt would be too costly or it fails.

> Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>

thanks!
-- 
Michal Hocko
SUSE Labs