1 files changed, 96 insertions, 15 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 06b7e8cc80ac..412178afd423 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -21,7 +21,8 @@ struct vm_area_struct;
 #define __GFP_DMA       ((__force gfp_t)0x01u)
 #define __GFP_HIGHMEM   ((__force gfp_t)0x02u)
 #define __GFP_DMA32     ((__force gfp_t)0x04u)
-
+#define __GFP_MOVABLE   ((__force gfp_t)0x08u)  /* Page is movable */
+#define GFP_ZONEMASK    (__GFP_DMA|__GFP_HIGHMEM|__GFP_DMA32|__GFP_MOVABLE)
 /*
  * Action modifiers - doesn't change the zoning
  *
@@ -51,7 +52,6 @@ struct vm_area_struct;
 #define __GFP_HARDWALL   ((__force gfp_t)0x20000u) /* Enforce hardwall cpuset memory allocs */
 #define __GFP_THISNODE  ((__force gfp_t)0x40000u)/* No fallback, no policies */
 #define __GFP_RECLAIMABLE ((__force gfp_t)0x80000u) /* Page is reclaimable */
-#define __GFP_MOVABLE   ((__force gfp_t)0x100000u)  /* Page is movable */
 
 #define __GFP_BITS_SHIFT 21     /* Room for 21 __GFP_FOO bits */
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
@@ -116,24 +116,105 @@ static inline int allocflags_to_migratetype(gfp_t gfp_flags)
                 ((gfp_flags & __GFP_RECLAIMABLE) != 0);
 }
 
-static inline enum zone_type gfp_zone(gfp_t flags)
-{
+#ifdef CONFIG_HIGHMEM
+#define OPT_ZONE_HIGHMEM ZONE_HIGHMEM
+#else
+#define OPT_ZONE_HIGHMEM ZONE_NORMAL
+#endif
+
 #ifdef CONFIG_ZONE_DMA
-        if (flags & __GFP_DMA)
-                return ZONE_DMA;
+#define OPT_ZONE_DMA ZONE_DMA
+#else
+#define OPT_ZONE_DMA ZONE_NORMAL
 #endif
+
 #ifdef CONFIG_ZONE_DMA32
-        if (flags & __GFP_DMA32)
-                return ZONE_DMA32;
+#define OPT_ZONE_DMA32 ZONE_DMA32
+#else
+#define OPT_ZONE_DMA32 ZONE_NORMAL
 #endif
-        if ((flags & (__GFP_HIGHMEM | __GFP_MOVABLE)) ==
-                        (__GFP_HIGHMEM | __GFP_MOVABLE))
-                return ZONE_MOVABLE;
-#ifdef CONFIG_HIGHMEM
-        if (flags & __GFP_HIGHMEM)
-                return ZONE_HIGHMEM;
+
+/*
+ * 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 ZONE_SHIFT 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 1bit of the lowest 3 bit (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+HIGHMEM+DMA32)
+ *       0xd    => BAD (MOVABLE+DMA32+DMA)
+ *       0xe    => BAD (MOVABLE+DMA32+HIGHMEM)
+ *       0xf    => BAD (MOVABLE+DMA32+HIGHMEM+DMA)
+ *
+ * ZONES_SHIFT must be <= 2 on 32 bit platforms.
+ */
+
+#if 16 * ZONES_SHIFT > BITS_PER_LONG
+#error ZONES_SHIFT too large to create GFP_ZONE_TABLE integer
+#endif
+
+#define GFP_ZONE_TABLE ( \
+        (ZONE_NORMAL << 0 * ZONES_SHIFT)                                \
+        | (OPT_ZONE_DMA << __GFP_DMA * ZONES_SHIFT)                     \
+        | (OPT_ZONE_HIGHMEM << __GFP_HIGHMEM * ZONES_SHIFT)             \
+        | (OPT_ZONE_DMA32 << __GFP_DMA32 * ZONES_SHIFT)                 \
+        | (ZONE_NORMAL << __GFP_MOVABLE * ZONES_SHIFT)                  \
+        | (OPT_ZONE_DMA << (__GFP_MOVABLE | __GFP_DMA) * ZONES_SHIFT)   \
+        | (ZONE_MOVABLE << (__GFP_MOVABLE | __GFP_HIGHMEM) * ZONES_SHIFT)\
+        | (OPT_ZONE_DMA32 << (__GFP_MOVABLE | __GFP_DMA32) * ZONES_SHIFT)\
+)
+
+/*
+ * GFP_ZONE_BAD is a bitmap for all combination 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 = flags & GFP_ZONEMASK;
+
+        z = (GFP_ZONE_TABLE >> (bit * ZONES_SHIFT)) &
+                                         ((1 << ZONES_SHIFT) - 1);
+
+        if (__builtin_constant_p(bit))
+                BUILD_BUG_ON((GFP_ZONE_BAD >> bit) & 1);
+        else {
+#ifdef CONFIG_DEBUG_VM
+                BUG_ON((GFP_ZONE_BAD >> bit) & 1);
 #endif
-        return ZONE_NORMAL;
+        }
+        return z;
 }
 
 /*