From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751834AbeEFSzs (ORCPT ); Sun, 6 May 2018 14:55:48 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38540 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751771AbeEFSzp (ORCPT ); Sun, 6 May 2018 14:55:45 -0400 Date: Sun, 6 May 2018 11:55:32 -0700 From: Matthew Wilcox To: Huaisheng HS1 Ye Cc: Michal Hocko , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "vbabka@suse.cz" , "mgorman@techsingularity.net" , "pasha.tatashin@oracle.com" , "alexander.levin@verizon.com" , "hannes@cmpxchg.org" , "penguin-kernel@I-love.SAKURA.ne.jp" , "colyli@suse.de" , NingTing Cheng , "linux-kernel@vger.kernel.org" Subject: Re: [External] Re: [PATCH 2/3] include/linux/gfp.h: use unsigned int in gfp_zone Message-ID: <20180506185532.GA13604@bombadil.infradead.org> References: <1525416729-108201-1-git-send-email-yehs1@lenovo.com> <1525416729-108201-3-git-send-email-yehs1@lenovo.com> <20180504133533.GR4535@dhcp22.suse.cz> <20180504154004.GB29829@bombadil.infradead.org> <20180506134814.GB7362@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 06, 2018 at 04:17:06PM +0000, Huaisheng HS1 Ye wrote: > Upload my current patch and testing platform info for reference. This patch has been tested > on a two sockets platform. Thank you! > It works, but some drivers or subsystem shall be modified to fit > these new type __GFP flags. > They use these flags directly to realize bit manipulations like this > below. > > eg. > 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 within this patch, the > above operations can cause problem. I don't think this actually causes problems. At least, no additional problems. These users will successfully clear __GFP_DMA and __GFP_HIGHMEM no matter what values GFP_DMA and GFP_HIGHMEM have; the only problem will be if someone calls them with a zone type they're not expecting (eg DMA32 for the first one or DMA for the second; or MOVABLE for either of them). The thing is, they're already buggy in those circumstances. > */ > -#define __GFP_DMA ((__force gfp_t)___GFP_DMA) > -#define __GFP_HIGHMEM ((__force gfp_t)___GFP_HIGHMEM) > -#define __GFP_DMA32 ((__force gfp_t)___GFP_DMA32) > +#define __GFP_DMA ((__force gfp_t)OPT_ZONE_DMA ^ ZONE_NORMAL) > +#define __GFP_HIGHMEM ((__force gfp_t)ZONE_MOVABLE ^ ZONE_NORMAL) > +#define __GFP_DMA32 ((__force gfp_t)OPT_ZONE_DMA32 ^ ZONE_NORMAL) > #define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ [...] > static inline enum zone_type gfp_zone(gfp_t flags) > { > enum zone_type z; > - int bit = (__force int) (flags & GFP_ZONEMASK); > + z = ((__force unsigned int)flags & ___GFP_ZONE_MASK) ^ ZONE_NORMAL; > > - z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > - ((1 << GFP_ZONES_SHIFT) - 1); > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > + if (z > OPT_ZONE_HIGHMEM) { > + z = OPT_ZONE_HIGHMEM + > + !!((__force unsigned int)flags & ___GFP_MOVABLE); > + } > return z; > } How about: +#define __GFP_HIGHMEM ((__force gfp_t)OPT_ZONE_HIGHMEM ^ ZONE_NORMAL) -#define __GFP_MOVABLE ((__force gfp_t)___GFP_MOVABLE) /* ZONE_MOVABLE allowed */ +#define __GFP_MOVABLE ((__force gfp_t)ZONE_MOVABLE ^ ZONE_NORMAL | \ + ___GFP_MOVABLE) Then I think you can just make it: static inline enum zone_type gfp_zone(gfp_t flags) { return ((__force int)flags & ___GFP_ZONE_MASK) ^ ZONE_NORMAL; } > @@ -370,42 +368,15 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags) > #error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer > #endif You should be able to delete GFP_ZONES_SHIFT too.