linux-kernel - Re: [PATCH 17/19] dm: get rid of superfluous gfp flags

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Date:	Fri, 15 Apr 2016 15:08:40 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Shaohua Li <shli@...nel.org>
Subject: Re: [PATCH 17/19] dm: get rid of superfluous gfp flags

On Fri 15-04-16 08:29:28, Mikulas Patocka wrote:
> 
> 
> On Mon, 11 Apr 2016, Michal Hocko wrote:
> 
> > From: Michal Hocko <mhocko@...e.com>
> > 
> > copy_params seems to be little bit confused about which allocation flags
> > to use. It enforces GFP_NOIO even though it uses
> > memalloc_noio_{save,restore} which enforces GFP_NOIO at the page
> 
> memalloc_noio_{save,restore} is used because __vmalloc is flawed and 
> doesn't respect GFP_NOIO properly (it doesn't use gfp flags when 
> allocating pagetables).

Yes and there are no plans to change __vmalloc to properly propagate gfp
flags through the whole call chain and that is why we have
memalloc_noio thingy. If that ever changes later the GFP_NOIO can be
added in favor of memalloc_noio API. Both are clearly redundant.
-- 
Michal Hocko
SUSE Labs