In paging_init the memblock limit is set to restrict any addresses
returned by early_alloc to fit within the initial direct kernel
mapping in swapper_pg_dir. This allows map_mem to allocate puds,
pmds and ptes from the initial direct kernel mapping.
The limit stays low after paging_init() though, meaning any
bootmem allocations will be from a restricted subset of memory.
Gigabyte huge pages, for instance, are normally allocated from
bootmem as their order (18) is too large for the default buddy
allocator (MAX_ORDER = 11).
This patch restores the memblock limit when map_mem has finished,
allowing gigabyte huge pages (and other objects) to be allocated
from all of bootmem.
Signed-off-by: Steve Capper <steve.capper@xxxxxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
arch/arm64/mm/mmu.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index eeecc9c..9fa027b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -297,6 +297,16 @@ static void __init map_mem(void)
{
struct memblock_region *reg;
+ /*
+ * Temporarily limit the memblock range. We need to do this as
+ * create_mapping requires puds, pmds and ptes to be allocated from
+ * memory addressable from the initial direct kernel mapping.
+ *
+ * The initial direct kernel mapping, located at swapper_pg_dir,
+ * gives us PGDIR_SIZE memory starting from PHYS_OFFSET (aligned).
+ */
+ memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);
+
/* map all the memory banks */
for_each_memblock(memory, reg) {
phys_addr_t start = reg->base;
@@ -307,6 +317,9 @@ static void __init map_mem(void)
create_mapping(start, __phys_to_virt(start), end - start);
}
+
+ /* Limit no longer required. */
+ memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);
}
/*
@@ -317,12 +330,6 @@ void __init paging_init(void)
{
void *zero_page;
- /*
- * Maximum PGDIR_SIZE addressable via the initial direct kernel
- * mapping in swapper_pg_dir.
- */
- memblock_set_current_limit((PHYS_OFFSET & PGDIR_MASK) + PGDIR_SIZE);
-
init_mem_pgprot();
map_mem();
--
1.8.1.4
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