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From: Matthew Wilcox <willy@infradead.org>
To: Huaisheng HS1 Ye <yehs1@lenovo.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"mhocko@suse.com" <mhocko@suse.com>,
	"vbabka@suse.cz" <vbabka@suse.cz>,
	"mgorman@techsingularity.net" <mgorman@techsingularity.net>,
	"alexander.levin@verizon.com" <alexander.levin@verizon.com>,
	"colyli@suse.de" <colyli@suse.de>,
	NingTing Cheng <chengnt@lenovo.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [External]  Re: [PATCH v1] include/linux/gfp.h: getting rid of GFP_ZONE_TABLE/BAD
Date: Sat, 12 May 2018 07:22:49 -0700	[thread overview]
Message-ID: <20180512142249.GA24215@bombadil.infradead.org> (raw)
In-Reply-To: <HK2PR03MB1684BC9802BC2E5C1BF2DC74929E0@HK2PR03MB1684.apcprd03.prod.outlook.com>

On Sat, May 12, 2018 at 11:35:00AM +0000, Huaisheng HS1 Ye wrote:
> > The point of this exercise is to actually encode the zone number in
> > the bottom bits of the GFP flags instead of something which has to be
> > interpreted into a zone number.  When somebody sets __GFP_MOVABLE, they
> > should also be setting ZONE_MOVABLE:
> > 
> > -#define __GFP_MOVABLE   ((__force gfp_t)___GFP_MOVABLE)  /* ZONE_MOVABLE allowed */
> > +#define __GFP_MOVABLE   ((__force gfp_t)(___GFP_MOVABLE | (ZONE_MOVABLE ^ ZONE_NORMAL)))
> > 
> I am afraid we couldn't do that, because __GFP_MOVABLE would be used potentially with other __GFPs like __GFP_DMA and __GFP_DMA32.

That's not a combination that makes much sense.  I know it's permitted today
(and it has the effect of being a no-op), but when you think about it, it
doesn't actually make any sense.

  reply	other threads:[~2018-05-12 14:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1525968625-40825-1-git-send-email-yehs1@lenovo.com>
2018-05-10 16:30 ` Matthew Wilcox
2018-05-11  3:24   ` [External] " Huaisheng HS1 Ye
2018-05-11 13:26     ` Matthew Wilcox
2018-05-12 11:35       ` Huaisheng HS1 Ye
2018-05-12 14:22         ` Matthew Wilcox [this message]
2018-05-16 12:12           ` Huaisheng HS1 Ye
2018-05-18  3:03       ` Huaisheng HS1 Ye

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