[PATCH] mm: cma: allocate cma areas bottom-up

[Roman Gushchin <guro@fb.com>]

Currently cma areas without a fixed base address are allocated
close to the end of the node. This placement is sub-optimal because
of how the compaction works: it effectively moves pages into
the cma area. In particular, it often brings in hot executable pages,
even if there is a plenty of free memory on the machine.
This results in more cma allocation failures.

Instead let's place cma areas close to the beginning of a node.
Cma first tries to start with highmem_start, so we shouldn't mess
up with DMA32. In this case the compaction will help to free cma
areas, resulting in better cma allocation success rates.

Signed-off-by: Roman Gushchin <guro@fb.com>
---
 include/linux/memblock.h |  5 +++--
 mm/cma.c                 |  4 ++--
 mm/memblock.c            | 26 +++++++++++++++-----------
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 9c5cc95c7cee..698188066450 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -384,8 +384,9 @@ static inline int memblock_get_region_node(const struct memblock_region *r)
 phys_addr_t memblock_phys_alloc_range(phys_addr_t size, phys_addr_t align,
 				      phys_addr_t start, phys_addr_t end);
 phys_addr_t memblock_alloc_range_nid(phys_addr_t size,
-				      phys_addr_t align, phys_addr_t start,
-				      phys_addr_t end, int nid, bool exact_nid);
+				     phys_addr_t align, phys_addr_t start,
+				     phys_addr_t end, int nid, bool exact_nid,
+				     bool bottom_up);
 phys_addr_t memblock_phys_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid);
 
 static inline phys_addr_t memblock_phys_alloc(phys_addr_t size,
diff --git a/mm/cma.c b/mm/cma.c
index 20c4f6f40037..1b42be6d059b 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -332,13 +332,13 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 		 */
 		if (base < highmem_start && limit > highmem_start) {
 			addr = memblock_alloc_range_nid(size, alignment,
-					highmem_start, limit, nid, true);
+					highmem_start, limit, nid, true, true);
 			limit = highmem_start;
 		}
 
 		if (!addr) {
 			addr = memblock_alloc_range_nid(size, alignment, base,
-					limit, nid, true);
+					limit, nid, true, true);
 			if (!addr) {
 				ret = -ENOMEM;
 				goto err;
diff --git a/mm/memblock.c b/mm/memblock.c
index b8b7be0561c4..c334b401fe16 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -272,6 +272,7 @@ __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
  *       %MEMBLOCK_ALLOC_ACCESSIBLE
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @flags: pick from blocks based on memory attributes
+ * @bottom_up: force bottom-up allocation
  *
  * Find @size free area aligned to @align in the specified range and node.
  *
@@ -289,7 +290,8 @@ __memblock_find_range_top_down(phys_addr_t start, phys_addr_t end,
 static phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
 					phys_addr_t end, int nid,
-					enum memblock_flags flags)
+					enum memblock_flags flags,
+					bool bottom_up)
 {
 	phys_addr_t kernel_end, ret;
 
@@ -305,9 +307,10 @@ static phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t size,
 
 	/*
 	 * try bottom-up allocation only when bottom-up mode
-	 * is set and @end is above the kernel image.
+	 * is set and @end is above the kernel image or
+	 * the bottom-up mode is enforced.
 	 */
-	if (memblock_bottom_up() && end > kernel_end) {
+	if ((memblock_bottom_up() && end > kernel_end) || bottom_up) {
 		phys_addr_t bottom_up_start;
 
 		/* make sure we will allocate above the kernel */
@@ -359,7 +362,7 @@ phys_addr_t __init_memblock memblock_find_in_range(phys_addr_t start,
 
 again:
 	ret = memblock_find_in_range_node(size, align, start, end,
-					    NUMA_NO_NODE, flags);
+					  NUMA_NO_NODE, flags, false);
 
 	if (!ret && (flags & MEMBLOCK_MIRROR)) {
 		pr_warn("Could not allocate %pap bytes of mirrored memory\n",
@@ -1331,6 +1334,7 @@ __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
  * @end: the upper bound of the memory region to allocate (phys address)
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  * @exact_nid: control the allocation fall back to other nodes
+ * @bottom_up: force bottom-up allocation
  *
  * The allocation is performed from memory region limited by
  * memblock.current_limit if @end == %MEMBLOCK_ALLOC_ACCESSIBLE.
@@ -1351,7 +1355,7 @@ __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
 phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 					phys_addr_t align, phys_addr_t start,
 					phys_addr_t end, int nid,
-					bool exact_nid)
+					bool exact_nid, bool bottom_up)
 {
 	enum memblock_flags flags = choose_memblock_flags();
 	phys_addr_t found;
@@ -1367,14 +1371,14 @@ phys_addr_t __init memblock_alloc_range_nid(phys_addr_t size,
 
 again:
 	found = memblock_find_in_range_node(size, align, start, end, nid,
-					    flags);
+					    flags, bottom_up);
 	if (found && !memblock_reserve(found, size))
 		goto done;
 
 	if (nid != NUMA_NO_NODE && !exact_nid) {
 		found = memblock_find_in_range_node(size, align, start,
 						    end, NUMA_NO_NODE,
-						    flags);
+						    flags, bottom_up);
 		if (found && !memblock_reserve(found, size))
 			goto done;
 	}
@@ -1423,7 +1427,7 @@ phys_addr_t __init memblock_phys_alloc_range(phys_addr_t size,
 		     __func__, (u64)size, (u64)align, &start, &end,
 		     (void *)_RET_IP_);
 	return memblock_alloc_range_nid(size, align, start, end, NUMA_NO_NODE,
-					false);
+					false, false);
 }
 
 /**
@@ -1442,7 +1446,7 @@ phys_addr_t __init memblock_phys_alloc_range(phys_addr_t size,
 phys_addr_t __init memblock_phys_alloc_try_nid(phys_addr_t size, phys_addr_t align, int nid)
 {
 	return memblock_alloc_range_nid(size, align, 0,
-					MEMBLOCK_ALLOC_ACCESSIBLE, nid, false);
+					MEMBLOCK_ALLOC_ACCESSIBLE, nid, false, false);
 }
 
 /**
@@ -1484,12 +1488,12 @@ static void * __init memblock_alloc_internal(
 		max_addr = memblock.current_limit;
 
 	alloc = memblock_alloc_range_nid(size, align, min_addr, max_addr, nid,
-					exact_nid);
+					exact_nid, false);
 
 	/* retry allocation without lower limit */
 	if (!alloc && min_addr)
 		alloc = memblock_alloc_range_nid(size, align, 0, max_addr, nid,
-						exact_nid);
+						exact_nid, false);
 
 	if (!alloc)
 		return NULL;
-- 
2.26.2