memblock: Factor the lowest level alloc function

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 27 insertions, 32 deletions

diff --git a/mm/memblock.c b/mm/memblock.c
index 13807f280ada..e264e8c70892 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -294,8 +294,8 @@ static u64 memblock_align_up(u64 addr, u64 size)
         return (addr + (size - 1)) & ~(size - 1);
 }
 
-static u64 __init memblock_alloc_nid_unreserved(u64 start, u64 end,
-                                           u64 size, u64 align)
+static u64 __init memblock_alloc_region(u64 start, u64 end,
+                                   u64 size, u64 align)
 {
         u64 base, res_base;
         long j;
@@ -318,6 +318,13 @@ static u64 __init memblock_alloc_nid_unreserved(u64 start, u64 end,
         return ~(u64)0;
 }
 
+u64 __weak __init memblock_nid_range(u64 start, u64 end, int *nid)
+{
+        *nid = 0;
+
+        return end;
+}
+
 static u64 __init memblock_alloc_nid_region(struct memblock_region *mp,
                                        u64 size, u64 align, int nid)
 {
@@ -333,8 +340,7 @@ static u64 __init memblock_alloc_nid_region(struct memblock_region *mp,
 
                 this_end = memblock_nid_range(start, end, &this_nid);
                 if (this_nid == nid) {
-                        u64 ret = memblock_alloc_nid_unreserved(start, this_end,
-                                                           size, align);
+                        u64 ret = memblock_alloc_region(start, this_end, size, align);
                         if (ret != ~(u64)0)
                                 return ret;
                 }
@@ -351,6 +357,10 @@ u64 __init memblock_alloc_nid(u64 size, u64 align, int nid)
 
         BUG_ON(0 == size);
 
+        /* We do a bottom-up search for a region with the right
+         * nid since that's easier considering how memblock_nid_range()
+         * works
+         */
         size = memblock_align_up(size, align);
 
         for (i = 0; i < mem->cnt; i++) {
@@ -383,7 +393,7 @@ u64 __init memblock_alloc_base(u64 size, u64 align, u64 max_addr)
 
 u64 __init __memblock_alloc_base(u64 size, u64 align, u64 max_addr)
 {
-        long i, j;
+        long i;
         u64 base = 0;
         u64 res_base;
 
@@ -396,33 +406,24 @@ u64 __init __memblock_alloc_base(u64 size, u64 align, u64 max_addr)
         if (max_addr == MEMBLOCK_ALLOC_ANYWHERE)
                 max_addr = MEMBLOCK_REAL_LIMIT;
 
+        /* Pump up max_addr */
+        if (max_addr == MEMBLOCK_ALLOC_ANYWHERE)
+                max_addr = ~(u64)0;
+
+        /* We do a top-down search, this tends to limit memory
+         * fragmentation by keeping early boot allocs near the
+         * top of memory
+         */
         for (i = memblock.memory.cnt - 1; i >= 0; i--) {
                 u64 memblockbase = memblock.memory.regions[i].base;
                 u64 memblocksize = memblock.memory.regions[i].size;
 
                 if (memblocksize < size)
                         continue;
-                if (max_addr == MEMBLOCK_ALLOC_ANYWHERE)
-                        base = memblock_align_down(memblockbase + memblocksize - size, align);
-                else if (memblockbase < max_addr) {
-                        base = min(memblockbase + memblocksize, max_addr);
-                        base = memblock_align_down(base - size, align);
-                } else
-                        continue;
-
-                while (base && memblockbase <= base) {
-                        j = memblock_overlaps_region(&memblock.reserved, base, size);
-                        if (j < 0) {
-                                /* this area isn't reserved, take it */
-                                if (memblock_add_region(&memblock.reserved, base, size) < 0)
-                                        return 0;
-                                return base;
-                        }
-                        res_base = memblock.reserved.regions[j].base;
-                        if (res_base < size)
-                                break;
-                        base = memblock_align_down(res_base - size, align);
-                }
+                base = min(memblockbase + memblocksize, max_addr);
+                res_base = memblock_alloc_region(memblockbase, base, size, align);
+                if (res_base != ~(u64)0)
+                        return res_base;
         }
         return 0;
 }
@@ -528,9 +529,3 @@ int memblock_is_region_reserved(u64 base, u64 size)
         return memblock_overlaps_region(&memblock.reserved, base, size) >= 0;
 }
 
-u64 __weak memblock_nid_range(u64 start, u64 end, int *nid)
-{
-        *nid = 0;
-
-        return end;
-}