1 files changed, 132 insertions, 109 deletions

diff --git a/mm/memblock.c b/mm/memblock.c
index 4618fda975a0..a0562d1a6ad4 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -58,28 +58,6 @@ static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, p
         return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
 }
 
-static long __init_memblock memblock_addrs_adjacent(phys_addr_t base1, phys_addr_t size1,
-                               phys_addr_t base2, phys_addr_t size2)
-{
-        if (base2 == base1 + size1)
-                return 1;
-        else if (base1 == base2 + size2)
-                return -1;
-
-        return 0;
-}
-
-static long __init_memblock memblock_regions_adjacent(struct memblock_type *type,
-                                 unsigned long r1, unsigned long r2)
-{
-        phys_addr_t base1 = type->regions[r1].base;
-        phys_addr_t size1 = type->regions[r1].size;
-        phys_addr_t base2 = type->regions[r2].base;
-        phys_addr_t size2 = type->regions[r2].size;
-
-        return memblock_addrs_adjacent(base1, size1, base2, size2);
-}
-
 long __init_memblock memblock_overlaps_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
 {
         unsigned long i;
@@ -206,14 +184,13 @@ static void __init_memblock memblock_remove_region(struct memblock_type *type, u
                 type->regions[i].size = type->regions[i + 1].size;
         }
         type->cnt--;
-}
 
-/* Assumption: base addr of region 1 < base addr of region 2 */
-static void __init_memblock memblock_coalesce_regions(struct memblock_type *type,
-                unsigned long r1, unsigned long r2)
-{
-        type->regions[r1].size += type->regions[r2].size;
-        memblock_remove_region(type, r2);
+        /* Special case for empty arrays */
+        if (type->cnt == 0) {
+                type->cnt = 1;
+                type->regions[0].base = 0;
+                type->regions[0].size = 0;
+        }
 }
 
 /* Defined below but needed now */
@@ -276,7 +253,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type)
                 return 0;
 
         /* Add the new reserved region now. Should not fail ! */
-        BUG_ON(memblock_add_region(&memblock.reserved, addr, new_size) < 0);
+        BUG_ON(memblock_add_region(&memblock.reserved, addr, new_size));
 
         /* If the array wasn't our static init one, then free it. We only do
          * that before SLAB is available as later on, we don't know whether
@@ -296,58 +273,99 @@ extern int __init_memblock __weak memblock_memory_can_coalesce(phys_addr_t addr1
         return 1;
 }
 
-static long __init_memblock memblock_add_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
+static long __init_memblock memblock_add_region(struct memblock_type *type,
+                                                phys_addr_t base, phys_addr_t size)
 {
-        unsigned long coalesced = 0;
-        long adjacent, i;
-
-        if ((type->cnt == 1) && (type->regions[0].size == 0)) {
-                type->regions[0].base = base;
-                type->regions[0].size = size;
-                return 0;
-        }
+        phys_addr_t end = base + size;
+        int i, slot = -1;
 
-        /* First try and coalesce this MEMBLOCK with another. */
+        /* First try and coalesce this MEMBLOCK with others */
         for (i = 0; i < type->cnt; i++) {
-                phys_addr_t rgnbase = type->regions[i].base;
-                phys_addr_t rgnsize = type->regions[i].size;
+                struct memblock_region *rgn = &type->regions[i];
+                phys_addr_t rend = rgn->base + rgn->size;
+
+                /* Exit if there's no possible hits */
+                if (rgn->base > end || rgn->size == 0)
+                        break;
 
-                if ((rgnbase == base) && (rgnsize == size))
-                        /* Already have this region, so we're done */
+                /* Check if we are fully enclosed within an existing
+                 * block
+                 */
+                if (rgn->base <= base && rend >= end)
                         return 0;
 
-                adjacent = memblock_addrs_adjacent(base, size, rgnbase, rgnsize);
-                /* Check if arch allows coalescing */
-                if (adjacent != 0 && type == &memblock.memory &&
-                    !memblock_memory_can_coalesce(base, size, rgnbase, rgnsize))
-                        break;
-                if (adjacent > 0) {
-                        type->regions[i].base -= size;
-                        type->regions[i].size += size;
-                        coalesced++;
-                        break;
-                } else if (adjacent < 0) {
-                        type->regions[i].size += size;
-                        coalesced++;
-                        break;
+                /* Check if we overlap or are adjacent with the bottom
+                 * of a block.
+                 */
+                if (base < rgn->base && end >= rgn->base) {
+                        /* If we can't coalesce, create a new block */
+                        if (!memblock_memory_can_coalesce(base, size,
+                                                          rgn->base,
+                                                          rgn->size)) {
+                                /* Overlap & can't coalesce are mutually
+                                 * exclusive, if you do that, be prepared
+                                 * for trouble
+                                 */
+                                WARN_ON(end != rgn->base);
+                                goto new_block;
+                        }
+                        /* We extend the bottom of the block down to our
+                         * base
+                         */
+                        rgn->base = base;
+                        rgn->size = rend - base;
+
+                        /* Return if we have nothing else to allocate
+                         * (fully coalesced)
+                         */
+                        if (rend >= end)
+                                return 0;
+
+                        /* We continue processing from the end of the
+                         * coalesced block.
+                         */
+                        base = rend;
+                        size = end - base;
+                }
+
+                /* Now check if we overlap or are adjacent with the
+                 * top of a block
+                 */
+                if (base <= rend && end >= rend) {
+                        /* If we can't coalesce, create a new block */
+                        if (!memblock_memory_can_coalesce(rgn->base,
+                                                          rgn->size,
+                                                          base, size)) {
+                                /* Overlap & can't coalesce are mutually
+                                 * exclusive, if you do that, be prepared
+                                 * for trouble
+                                 */
+                                WARN_ON(rend != base);
+                                goto new_block;
+                        }
+                        /* We adjust our base down to enclose the
+                         * original block and destroy it. It will be
+                         * part of our new allocation. Since we've
+                         * freed an entry, we know we won't fail
+                         * to allocate one later, so we won't risk
+                         * losing the original block allocation.
+                         */
+                        size += (base - rgn->base);
+                        base = rgn->base;
+                        memblock_remove_region(type, i--);
                 }
         }
 
-        /* If we plugged a hole, we may want to also coalesce with the
-         * next region
+        /* If the array is empty, special case, replace the fake
+         * filler region and return
          */
-        if ((i < type->cnt - 1) && memblock_regions_adjacent(type, i, i+1) &&
-            ((type != &memblock.memory || memblock_memory_can_coalesce(type->regions[i].base,
-                                                             type->regions[i].size,
-                                                             type->regions[i+1].base,
-                                                             type->regions[i+1].size)))) {
-                memblock_coalesce_regions(type, i, i+1);
-                coalesced++;
+        if ((type->cnt == 1) && (type->regions[0].size == 0)) {
+                type->regions[0].base = base;
+                type->regions[0].size = size;
+                return 0;
         }
 
-        if (coalesced)
-                return coalesced;
-
+ new_block:
         /* If we are out of space, we fail. It's too late to resize the array
          * but then this shouldn't have happened in the first place.
          */
@@ -362,13 +380,14 @@ static long __init_memblock memblock_add_region(struct memblock_type *type, phys
                 } else {
                         type->regions[i+1].base = base;
                         type->regions[i+1].size = size;
+                        slot = i + 1;
                         break;
                 }
         }
-
         if (base < type->regions[0].base) {
                 type->regions[0].base = base;
                 type->regions[0].size = size;
+                slot = 0;
         }
         type->cnt++;
 
@@ -376,7 +395,8 @@ static long __init_memblock memblock_add_region(struct memblock_type *type, phys
          * our allocation and return an error
          */
         if (type->cnt == type->max && memblock_double_array(type)) {
-                type->cnt--;
+                BUG_ON(slot < 0);
+                memblock_remove_region(type, slot);
                 return -1;
         }
 
@@ -389,52 +409,55 @@ long __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
 
 }
 
-static long __init_memblock __memblock_remove(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
+static long __init_memblock __memblock_remove(struct memblock_type *type,
+                                              phys_addr_t base, phys_addr_t size)
 {
-        phys_addr_t rgnbegin, rgnend;
         phys_addr_t end = base + size;
         int i;
 
-        rgnbegin = rgnend = 0; /* supress gcc warnings */
-
-        /* Find the region where (base, size) belongs to */
-        for (i=0; i < type->cnt; i++) {
-                rgnbegin = type->regions[i].base;
-                rgnend = rgnbegin + type->regions[i].size;
+        /* Walk through the array for collisions */
+        for (i = 0; i < type->cnt; i++) {
+                struct memblock_region *rgn = &type->regions[i];
+                phys_addr_t rend = rgn->base + rgn->size;
 
-                if ((rgnbegin <= base) && (end <= rgnend))
+                /* Nothing more to do, exit */
+                if (rgn->base > end || rgn->size == 0)
                         break;
-        }
 
-        /* Didn't find the region */
-        if (i == type->cnt)
-                return -1;
+                /* If we fully enclose the block, drop it */
+                if (base <= rgn->base && end >= rend) {
+                        memblock_remove_region(type, i--);
+                        continue;
+                }
 
-        /* Check to see if we are removing entire region */
-        if ((rgnbegin == base) && (rgnend == end)) {
-                memblock_remove_region(type, i);
-                return 0;
-        }
+                /* If we are fully enclosed within a block
+                 * then we need to split it and we are done
+                 */
+                if (base > rgn->base && end < rend) {
+                        rgn->size = base - rgn->base;
+                        if (!memblock_add_region(type, end, rend - end))
+                                return 0;
+                        /* Failure to split is bad, we at least
+                         * restore the block before erroring
+                         */
+                        rgn->size = rend - rgn->base;
+                        WARN_ON(1);
+                        return -1;
+                }
 
-        /* Check to see if region is matching at the front */
-        if (rgnbegin == base) {
-                type->regions[i].base = end;
-                type->regions[i].size -= size;
-                return 0;
-        }
+                /* Check if we need to trim the bottom of a block */
+                if (rgn->base < end && rend > end) {
+                        rgn->size -= end - rgn->base;
+                        rgn->base = end;
+                        break;
+                }
 
-        /* Check to see if the region is matching at the end */
-        if (rgnend == end) {
-                type->regions[i].size -= size;
-                return 0;
-        }
+                /* And check if we need to trim the top of a block */
+                if (base < rend)
+                        rgn->size -= rend - base;
 
-        /*
-         * We need to split the entry -  adjust the current one to the
-         * beginging of the hole and add the region after hole.
-         */
-        type->regions[i].size = base - type->regions[i].base;
-        return memblock_add_region(type, end, rgnend - end);
+        }
+        return 0;
 }
 
 long __init_memblock memblock_remove(phys_addr_t base, phys_addr_t size)
@@ -467,7 +490,7 @@ phys_addr_t __init __memblock_alloc_base(phys_addr_t size, phys_addr_t align, ph
 
         found = memblock_find_base(size, align, 0, max_addr);
         if (found != MEMBLOCK_ERROR &&
-            memblock_add_region(&memblock.reserved, found, size) >= 0)
+            !memblock_add_region(&memblock.reserved, found, size))
                 return found;
 
         return 0;
@@ -548,7 +571,7 @@ static phys_addr_t __init memblock_alloc_nid_region(struct memblock_region *mp,
                 if (this_nid == nid) {
                         phys_addr_t ret = memblock_find_region(start, this_end, size, align);
                         if (ret != MEMBLOCK_ERROR &&
-                            memblock_add_region(&memblock.reserved, ret, size) >= 0)
+                            !memblock_add_region(&memblock.reserved, ret, size))
                                 return ret;
                 }
                 start = this_end;