From: Matthew Wilcox <willy@infradead.org>
To: Huaisheng HS1 Ye <yehs1@lenovo.com>
Cc: Michal Hocko <mhocko@kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"vbabka@suse.cz" <vbabka@suse.cz>,
"mgorman@techsingularity.net" <mgorman@techsingularity.net>,
"pasha.tatashin@oracle.com" <pasha.tatashin@oracle.com>,
"alexander.levin@verizon.com" <alexander.levin@verizon.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
"penguin-kernel@I-love.SAKURA.ne.jp"
<penguin-kernel@I-love.SAKURA.ne.jp>,
"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 2/3] include/linux/gfp.h: use unsigned int in gfp_zone
Date: Sun, 6 May 2018 06:48:14 -0700 [thread overview]
Message-ID: <20180506134814.GB7362@bombadil.infradead.org> (raw)
In-Reply-To: <HK2PR03MB168459A1C4FB2B7D3E1F6A4A92840@HK2PR03MB1684.apcprd03.prod.outlook.com>
On Sun, May 06, 2018 at 09:32:15AM +0000, Huaisheng HS1 Ye wrote:
> This idea is great, we can replace GFP_ZONE_TABLE and GFP_ZONE_BAD with it.
> I have realized it preliminarily based on your code and tested it on a 2 sockets platform. Fortunately, we got a positive test result.
Great!
> I made some adjustments for __GFP_HIGHMEM, this flag is special than others, because the return result of gfp_zone has two possibilities, which depend on ___GFP_MOVABLE has been enabled or disabled.
> When ___GFP_MOVABLE has been enabled, ZONE_MOVABLE shall be returned. When disabled, OPT_ZONE_HIGHMEM shall be used.
>
> #define __GFP_DMA ((__force gfp_t)OPT_ZONE_DMA ^ ZONE_NORMAL)
> #define __GFP_HIGHMEM ((__force gfp_t)ZONE_MOVABLE ^ ZONE_NORMAL)
I'm not sure this is right ... Let me think about this a little.
> #define __GFP_DMA32 ((__force gfp_t)OPT_ZONE_DMA32 ^ ZONE_NORMAL)
> #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */
> #define GFP_ZONEMASK ((__force gfp_t)___GFP_ZONE_MASK | ___GFP_MOVABLE)
>
> The present situation is that, based on this change, the bits of flags, __GFP_DMA and __GFP_HIGHMEM and __GFP_DMA32, have been encoded.
> That is totally different from existing code, you know in kernel scope, there are many drivers or subsystems use these flags directly to realize bit manipulations like this below,
> swiotlb-xen.c (drivers\xen): flags &= ~(__GFP_DMA | __GFP_HIGHMEM);
> extent_io.c (fs\btrfs): mask &= ~(__GFP_DMA32|__GFP_HIGHMEM);
>
> Because of these flags have been encoded, the above operations can cause problem.
> I am trying to get a solution to resolve it. Any progress will be reported.
These users probably want:
flags &= GFP_RECLAIM_MASK;
next prev parent reply other threads:[~2018-05-06 13:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-04 6:52 [PATCH 0/3] Some fixes for mm code optimization Huaisheng Ye
[not found] ` <1525416729-108201-4-git-send-email-yehs1@lenovo.com>
2018-05-04 13:18 ` [PATCH 3/3] mm/page_alloc: Fix typo in debug info of calculate_node_totalpages Michal Hocko
2018-05-05 2:10 ` [External] " Huaisheng HS1 Ye
2018-05-09 7:48 ` Michal Hocko
[not found] ` <1525416729-108201-3-git-send-email-yehs1@lenovo.com>
2018-05-04 13:35 ` [PATCH 2/3] include/linux/gfp.h: use unsigned int in gfp_zone Michal Hocko
2018-05-04 15:40 ` Matthew Wilcox
2018-05-04 17:50 ` [External] " Huaisheng HS1 Ye
2018-05-06 9:32 ` Huaisheng HS1 Ye
2018-05-06 13:48 ` Matthew Wilcox [this message]
2018-05-06 16:17 ` Huaisheng HS1 Ye
2018-05-06 18:55 ` Matthew Wilcox
2018-05-07 17:16 ` Huaisheng HS1 Ye
2018-05-07 18:44 ` Matthew Wilcox
2018-05-07 21:25 ` David Sterba
2018-05-08 0:25 ` Matthew Wilcox
2018-05-09 9:36 ` David Sterba
2018-05-15 11:54 ` Matthew Wilcox
2018-05-21 17:06 ` David Sterba
2018-05-09 14:57 ` Huaisheng HS1 Ye
2018-05-08 0:25 ` Huaisheng HS1 Ye
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