[RFC PATCH v3 1/9] include/linux/gfp.h: get rid of GFP_ZONE_TABLE/BAD

2018-05-23 Thread Huaisheng Ye 
From: 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.
__GFP_ZONE_MOVABLE is created to realize it.

With this patch, just enabling __GFP_MOVABLE and __GFP_HIGHMEM is not
enough to get ZONE_MOVABLE from gfp_zone. All subsystems should use
GFP_HIGHUSER_MOVABLE directly to achieve that.

Decode zone number directly from bottom three bits of flags in gfp_zone.
The theory of encoding and decoding is,
A ^ B ^ B = A

Suggested-by: Matthew Wilcox 
Signed-off-by: Huaisheng Ye 
Cc: Andrew Morton 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: Kate Stewart 
Cc: "Levin, Alexander (Sasha Levin)" 
Cc: Greg Kroah-Hartman 
Cc: Christoph Hellwig 
---
 include/linux/gfp.h | 107 ++--
 1 file changed, 20 insertions(+), 87 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 1a4582b..f76ccd76 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_HIGH0x20u
@@ -53,11 +51,15 @@
  * 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)OPT_ZONE_HIGHMEM ^ 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)
+/* bottom 3 bits of GFP bitmasks are used for zone number encoded*/
+#define __GFP_ZONE_MASK ((__force gfp_t)___GFP_ZONE_MASK)
+#define __GFP_ZONE_MOVABLE \
+   ((__force gfp_t)(ZONE_MOVABLE ^ ZONE_NORMAL) | ___GFP_MOVABLE)
 
 /*
  * Page mobility and placement hints
@@ -268,6 +270,13 @@
  *   available and will not wake kswapd/kcompactd on failure. The _LIGHT
  *   version does not attempt reclaim/compaction at all and is by default used
  *   in page fault path, while the non-light is used by khugepaged.
+ *
+ * GFP_NORMAL() is used to clear bottom 3 bits of GFP bitmask. Actually it
+ *   returns encoded ZONE_NORMAL bits.
+ *
+ * GFP_NORMAL_UNMOVABLE() is similar to GFP_NORMAL, but it clear bottom 4 bits
+ *   of GFP bitmask. Excepting the encoded ZONE_NORMAL bits, it clears MOVABLE
+ *   flags as well.
  */
 #define GFP_ATOMIC (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
 #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS)
@@ -279,10 +288,12 @@
 #define GFP_DMA__GFP_DMA
 #define GFP_DMA32  __GFP_DMA32
 #define GFP_HIGHUSER   (GFP_USER | __GFP_HIGHMEM)
-#define GFP_HIGHUSER_MOVABLE   (GFP_HIGHUSER | __GFP_MOVABLE)
+#define GFP_HIGHUSER_MOVABLE   (GFP_USER | __GFP_ZONE_MOVABLE)
 #define GFP_TRANSHUGE_LIGHT((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE  (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
+#define GFP_NORMAL(gfp)((gfp) & ~__GFP_ZONE_MASK)
+#define GFP_NORMAL_UNMOVABLE(gfp) ((gfp) & ~GFP_ZONEMASK)
 
 /* Convert GFP flags to their corresponding migrate type */
 #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
@@ -326,87 +337,9 @@ 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

[RFC PATCH v3 1/9] include/linux/gfp.h: get rid of GFP_ZONE_TABLE/BAD

2018-05-23 Thread Huaisheng Ye 
From: 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.
__GFP_ZONE_MOVABLE is created to realize it.

With this patch, just enabling __GFP_MOVABLE and __GFP_HIGHMEM is not
enough to get ZONE_MOVABLE from gfp_zone. All subsystems should use
GFP_HIGHUSER_MOVABLE directly to achieve that.

Decode zone number directly from bottom three bits of flags in gfp_zone.
The theory of encoding and decoding is,
A ^ B ^ B = A

Suggested-by: Matthew Wilcox 
Signed-off-by: Huaisheng Ye 
Cc: Andrew Morton 
Cc: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Mel Gorman 
Cc: Kate Stewart 
Cc: "Levin, Alexander (Sasha Levin)" 
Cc: Greg Kroah-Hartman 
Cc: Christoph Hellwig 
---
 include/linux/gfp.h | 107 ++--
 1 file changed, 20 insertions(+), 87 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 1a4582b..f76ccd76 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_HIGH0x20u
@@ -53,11 +51,15 @@
  * 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)OPT_ZONE_HIGHMEM ^ 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)
+/* bottom 3 bits of GFP bitmasks are used for zone number encoded*/
+#define __GFP_ZONE_MASK ((__force gfp_t)___GFP_ZONE_MASK)
+#define __GFP_ZONE_MOVABLE \
+   ((__force gfp_t)(ZONE_MOVABLE ^ ZONE_NORMAL) | ___GFP_MOVABLE)
 
 /*
  * Page mobility and placement hints
@@ -268,6 +270,13 @@
  *   available and will not wake kswapd/kcompactd on failure. The _LIGHT
  *   version does not attempt reclaim/compaction at all and is by default used
  *   in page fault path, while the non-light is used by khugepaged.
+ *
+ * GFP_NORMAL() is used to clear bottom 3 bits of GFP bitmask. Actually it
+ *   returns encoded ZONE_NORMAL bits.
+ *
+ * GFP_NORMAL_UNMOVABLE() is similar to GFP_NORMAL, but it clear bottom 4 bits
+ *   of GFP bitmask. Excepting the encoded ZONE_NORMAL bits, it clears MOVABLE
+ *   flags as well.
  */
 #define GFP_ATOMIC (__GFP_HIGH|__GFP_ATOMIC|__GFP_KSWAPD_RECLAIM)
 #define GFP_KERNEL (__GFP_RECLAIM | __GFP_IO | __GFP_FS)
@@ -279,10 +288,12 @@
 #define GFP_DMA__GFP_DMA
 #define GFP_DMA32  __GFP_DMA32
 #define GFP_HIGHUSER   (GFP_USER | __GFP_HIGHMEM)
-#define GFP_HIGHUSER_MOVABLE   (GFP_HIGHUSER | __GFP_MOVABLE)
+#define GFP_HIGHUSER_MOVABLE   (GFP_USER | __GFP_ZONE_MOVABLE)
 #define GFP_TRANSHUGE_LIGHT((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)
 #define GFP_TRANSHUGE  (GFP_TRANSHUGE_LIGHT | __GFP_DIRECT_RECLAIM)
+#define GFP_NORMAL(gfp)((gfp) & ~__GFP_ZONE_MASK)
+#define GFP_NORMAL_UNMOVABLE(gfp) ((gfp) & ~GFP_ZONEMASK)
 
 /* Convert GFP flags to their corresponding migrate type */
 #define GFP_MOVABLE_MASK (__GFP_RECLAIMABLE|__GFP_MOVABLE)
@@ -326,87 +337,9 @@ 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