linux-kernel - Re: [PATCH 1/1] Remove hardcoding of ___GFP

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Message-ID: <20170428074028.GF8143@dhcp22.suse.cz>
Date:   Fri, 28 Apr 2017 09:40:29 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Igor Stoppa <igor.stoppa@...wei.com>
Cc:     namhyung@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Remove hardcoding of ___GFP_xxx bitmasks

On Thu 27-04-17 17:06:05, Igor Stoppa wrote:
> 
> 
> On 27/04/17 16:41, Michal Hocko wrote:
> > On Wed 26-04-17 18:29:08, Igor Stoppa wrote:
> > [...]
> >> If you prefer to have this patch only as part of the larger patchset,
> >> I'm also fine with it.
> > 
> > I agree that the situation is not ideal. If a larger set of changes
> > would benefit from this change then it would clearly add arguments...
> 
> Ok, then I'll send it out as part of the larger RFC set.
> 
> 
> >> Also, if you could reply to [1], that would be greatly appreciated.
> > 
> > I will try to get to it but from a quick glance, yet-another-zone will
> > hit a lot of opposition...
> 
> The most basic questions, that I hope can be answered with Yes/No =) are:
> 
> - should a new zone be added after DMA32?
> 
> - should I try hard to keep the mask fitting a 32bit word - at least for
> hose who do not use the new zone - or is it ok to just stretch it to 64
> bits?

Do not add a new zone, really. What you seem to be looking for is an
allocator on top of the page/memblock allocator which does write
protection on top. I understand that you would like to avoid object
management duplication but I am not really sure how much you can re-use
what slab allocators do already, anyway. I will respond to the original
thread to not mix things together.
-- 
Michal Hocko
SUSE Labs