From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id E99E16B0622 for ; Thu, 10 May 2018 11:58:37 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id a14-v6so1429928plt.7 for ; Thu, 10 May 2018 08:58:37 -0700 (PDT) Received: from dev31.localdomain ([103.244.59.4]) by mx.google.com with ESMTP id t76-v6si929899pgc.627.2018.05.10.08.58.36 for ; Thu, 10 May 2018 08:58:36 -0700 (PDT) From: Huaisheng Ye Subject: [PATCH v1] include/linux/gfp.h: getting rid of GFP_ZONE_TABLE/BAD Date: Fri, 11 May 2018 00:10:25 +0800 Message-Id: <1525968625-40825-1-git-send-email-yehs1@lenovo.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: mhocko@suse.com, willy@infradead.org, vbabka@suse.cz, mgorman@techsingularity.net, alexander.levin@verizon.com, colyli@suse.de, chengnt@lenovo.com, linux-kernel@vger.kernel.org, Huaisheng Ye Replace GFP_ZONE_TABLE and GFP_ZONE_BAD with encoded zone number. Delete ___GFP_DMA, ___GFP_HIGHMEM and ___GFP_DMA32 from GFP bitmasks, the bottom three bits of GFP mask is reserved for storing encoded zone number. The encoding method is XOR. Get zone number from enum zone_type, then encode the number with ZONE_NORMAL by XOR operation. The goal is to make sure ZONE_NORMAL can be encoded to zero. So, the compatibility can be guaranteed, such as GFP_KERNEL and GFP_ATOMIC can be used as before. Reserve __GFP_MOVABLE in bit 3, so that it can continue to be used as a flag. Same as before, __GFP_MOVABLE respresents movable migrate type for ZONE_DMA, ZONE_DMA32, and ZONE_NORMAL. But when it is enabled with __GFP_HIGHMEM, ZONE_MOVABLE shall be returned instead of ZONE_HIGHMEM. Decode zone number within gfp_zone, firstly decode its number with bottom three bits of flags. Then, return correct zone_type according to flag movable if zone type is larger than OPT_ZONE_HIGHMEM. The theory of encoding and decoding is, A ^ B ^ B = A Suggested-by: Matthew Wilcox Signed-off-by: Huaisheng Ye --- include/linux/gfp.h | 94 +++++++---------------------------------------------- 1 file changed, 11 insertions(+), 83 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 1a4582b..578cef7 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -16,9 +16,7 @@ */ /* Plain integer GFP bitmasks. Do not use this directly. */ -#define ___GFP_DMA 0x01u -#define ___GFP_HIGHMEM 0x02u -#define ___GFP_DMA32 0x04u +#define ___GFP_ZONE_MASK 0x07u #define ___GFP_MOVABLE 0x08u #define ___GFP_RECLAIMABLE 0x10u #define ___GFP_HIGH 0x20u @@ -53,11 +51,11 @@ * without the underscores and use them consistently. The definitions here may * be used in bit comparisons. */ -#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 */ -#define GFP_ZONEMASK (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE) +#define GFP_ZONEMASK ((__force gfp_t)___GFP_ZONE_MASK | ___GFP_MOVABLE) /* * Page mobility and placement hints @@ -326,86 +324,16 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags) #define OPT_ZONE_DMA32 ZONE_NORMAL #endif -/* - * GFP_ZONE_TABLE is a word size bitstring that is used for looking up the - * zone to use given the lowest 4 bits of gfp_t. Entries are GFP_ZONES_SHIFT - * bits long and there are 16 of them to cover all possible combinations of - * __GFP_DMA, __GFP_DMA32, __GFP_MOVABLE and __GFP_HIGHMEM. - * - * The zone fallback order is MOVABLE=>HIGHMEM=>NORMAL=>DMA32=>DMA. - * But GFP_MOVABLE is not only a zone specifier but also an allocation - * policy. Therefore __GFP_MOVABLE plus another zone selector is valid. - * Only 1 bit of the lowest 3 bits (DMA,DMA32,HIGHMEM) can be set to "1". - * - * bit result - * ================= - * 0x0 => NORMAL - * 0x1 => DMA or NORMAL - * 0x2 => HIGHMEM or NORMAL - * 0x3 => BAD (DMA+HIGHMEM) - * 0x4 => DMA32 or DMA or NORMAL - * 0x5 => BAD (DMA+DMA32) - * 0x6 => BAD (HIGHMEM+DMA32) - * 0x7 => BAD (HIGHMEM+DMA32+DMA) - * 0x8 => NORMAL (MOVABLE+0) - * 0x9 => DMA or NORMAL (MOVABLE+DMA) - * 0xa => MOVABLE (Movable is valid only if HIGHMEM is set too) - * 0xb => BAD (MOVABLE+HIGHMEM+DMA) - * 0xc => DMA32 (MOVABLE+DMA32) - * 0xd => BAD (MOVABLE+DMA32+DMA) - * 0xe => BAD (MOVABLE+DMA32+HIGHMEM) - * 0xf => BAD (MOVABLE+DMA32+HIGHMEM+DMA) - * - * GFP_ZONES_SHIFT must be <= 2 on 32 bit platforms. - */ - -#if defined(CONFIG_ZONE_DEVICE) && (MAX_NR_ZONES-1) <= 4 -/* ZONE_DEVICE is not a valid GFP zone specifier */ -#define GFP_ZONES_SHIFT 2 -#else -#define GFP_ZONES_SHIFT ZONES_SHIFT -#endif - -#if 16 * GFP_ZONES_SHIFT > BITS_PER_LONG -#error GFP_ZONES_SHIFT too large to create GFP_ZONE_TABLE integer -#endif - -#define GFP_ZONE_TABLE ( \ - (ZONE_NORMAL << 0 * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << ___GFP_DMA * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_HIGHMEM << ___GFP_HIGHMEM * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA32 << ___GFP_DMA32 * GFP_ZONES_SHIFT) \ - | (ZONE_NORMAL << ___GFP_MOVABLE * GFP_ZONES_SHIFT) \ - | (OPT_ZONE_DMA << (___GFP_MOVABLE | ___GFP_DMA) * GFP_ZONES_SHIFT) \ - | (ZONE_MOVABLE << (___GFP_MOVABLE | ___GFP_HIGHMEM) * GFP_ZONES_SHIFT)\ - | (OPT_ZONE_DMA32 << (___GFP_MOVABLE | ___GFP_DMA32) * GFP_ZONES_SHIFT)\ -) - -/* - * GFP_ZONE_BAD is a bitmap for all combinations of __GFP_DMA, __GFP_DMA32 - * __GFP_HIGHMEM and __GFP_MOVABLE that are not permitted. One flag per - * entry starting with bit 0. Bit is set if the combination is not - * allowed. - */ -#define GFP_ZONE_BAD ( \ - 1 << (___GFP_DMA | ___GFP_HIGHMEM) \ - | 1 << (___GFP_DMA | ___GFP_DMA32) \ - | 1 << (___GFP_DMA32 | ___GFP_HIGHMEM) \ - | 1 << (___GFP_DMA | ___GFP_DMA32 | ___GFP_HIGHMEM) \ - | 1 << (___GFP_MOVABLE | ___GFP_HIGHMEM | ___GFP_DMA) \ - | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA) \ - | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_HIGHMEM) \ - | 1 << (___GFP_MOVABLE | ___GFP_DMA32 | ___GFP_DMA | ___GFP_HIGHMEM) \ -) - 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; + + if (z > OPT_ZONE_HIGHMEM) + z = OPT_ZONE_HIGHMEM + + !!((__force unsigned int)flags & ___GFP_MOVABLE); - z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & - ((1 << GFP_ZONES_SHIFT) - 1); - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); + VM_BUG_ON(z > ZONE_MOVABLE); return z; } -- 1.8.3.1