From 993ba1585cbb03fab012e41d1a5d24330a283b31 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 5 Apr 2011 00:24:00 +0200 Subject: [PATCH] x86-32, numa: Update remap allocator comments Now that remap allocator is cleaned up, update comments such that they are in docbook function description format and reflect the actual implementation. Signed-off-by: Tejun Heo Link: http://lkml.kernel.org/r/1301955840-7246-15-git-send-email-tj@kernel.org Acked-by: Yinghai Lu Cc: David Rientjes Signed-off-by: H. Peter Anvin --- arch/x86/mm/numa_32.c | 56 ++++++++++++++++++++++++++++++++----------- 1 file changed, 42 insertions(+), 14 deletions(-) diff --git a/arch/x86/mm/numa_32.c b/arch/x86/mm/numa_32.c index f325e6fab75b..c757c0a3b529 100644 --- a/arch/x86/mm/numa_32.c +++ b/arch/x86/mm/numa_32.c @@ -176,17 +176,31 @@ static void __init allocate_pgdat(int nid) } /* - * In the DISCONTIGMEM and SPARSEMEM memory model, a portion of the kernel - * virtual address space (KVA) is reserved and portions of nodes are mapped - * using it. This is to allow node-local memory to be allocated for - * structures that would normally require ZONE_NORMAL. The memory is - * allocated with alloc_remap() and callers should be prepared to allocate - * from the bootmem allocator instead. + * Remap memory allocator */ static unsigned long node_remap_start_pfn[MAX_NUMNODES]; static void *node_remap_end_vaddr[MAX_NUMNODES]; static void *node_remap_alloc_vaddr[MAX_NUMNODES]; +/** + * alloc_remap - Allocate remapped memory + * @nid: NUMA node to allocate memory from + * @size: The size of allocation + * + * Allocate @size bytes from the remap area of NUMA node @nid. The + * size of the remap area is predetermined by init_alloc_remap() and + * only the callers considered there should call this function. For + * more info, please read the comment on top of init_alloc_remap(). + * + * The caller must be ready to handle allocation failure from this + * function and fall back to regular memory allocator in such cases. + * + * CONTEXT: + * Single CPU early boot context. + * + * RETURNS: + * Pointer to the allocated memory on success, %NULL on failure. + */ void *alloc_remap(int nid, unsigned long size) { void *allocation = node_remap_alloc_vaddr[nid]; @@ -238,6 +252,28 @@ void resume_map_numa_kva(pgd_t *pgd_base) } #endif +/** + * init_alloc_remap - Initialize remap allocator for a NUMA node + * @nid: NUMA node to initizlie remap allocator for + * + * NUMA nodes may end up without any lowmem. As allocating pgdat and + * memmap on a different node with lowmem is inefficient, a special + * remap allocator is implemented which can be used by alloc_remap(). + * + * For each node, the amount of memory which will be necessary for + * pgdat and memmap is calculated and two memory areas of the size are + * allocated - one in the node and the other in lowmem; then, the area + * in the node is remapped to the lowmem area. + * + * As pgdat and memmap must be allocated in lowmem anyway, this + * doesn't waste lowmem address space; however, the actual lowmem + * which gets remapped over is wasted. The amount shouldn't be + * problematic on machines this feature will be used. + * + * Initialization failure isn't fatal. alloc_remap() is used + * opportunistically and the callers will fall back to other memory + * allocation mechanisms on failure. + */ static __init void init_alloc_remap(int nid) { unsigned long size, pfn; @@ -306,14 +342,6 @@ void __init initmem_init(void) { int nid; - /* - * When mapping a NUMA machine we allocate the node_mem_map arrays - * from node local memory. They are then mapped directly into KVA - * between zone normal and vmalloc space. Calculate the size of - * this space and use it to adjust the boundary between ZONE_NORMAL - * and ZONE_HIGHMEM. - */ - get_memcfg_numa(); numa_init_array(); -- 2.34.1