From 91eea67c6d8704396a98226508c56a8501e141e3 Mon Sep 17 00:00:00 2001 From: Mark Nelson Date: Wed, 21 Apr 2010 16:21:03 +0000 Subject: powerpc/mm: Track backing pages allocated by vmemmap_populate() We need to keep track of the backing pages that get allocated by vmemmap_populate() so that when we use kdump, the dump-capture kernel knows where these pages are. We use a simple linked list of structures that contain the physical address of the backing page and corresponding virtual address to track the backing pages. To save space, we just use a pointer to the next struct vmemmap_backing. We can also do this because we never remove nodes. We call the pointer "list" to be compatible with changes made to the crash utility. vmemmap_populate() is called either at boot-time or on a memory hotplug operation. We don't have to worry about the boot-time calls because they will be inherently single-threaded, and for a memory hotplug operation vmemmap_populate() is called through: sparse_add_one_section() | V kmalloc_section_memmap() | V sparse_mem_map_populate() | V vmemmap_populate() and in sparse_add_one_section() we're protected by pgdat_resize_lock(). So, we don't need a spinlock to protect the vmemmap_list. We allocate space for the vmemmap_backing structs by allocating whole pages in vmemmap_list_alloc() and then handing out chunks of this to vmemmap_list_populate(). This means that we waste at most just under one page, but this keeps the code is simple. Signed-off-by: Mark Nelson Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/mm/init_64.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'arch/powerpc/mm/init_64.c') diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c index d7fa50b09b4a..e267f223fdff 100644 --- a/arch/powerpc/mm/init_64.c +++ b/arch/powerpc/mm/init_64.c @@ -252,6 +252,47 @@ static void __meminit vmemmap_create_mapping(unsigned long start, } #endif /* CONFIG_PPC_BOOK3E */ +struct vmemmap_backing *vmemmap_list; + +static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node) +{ + static struct vmemmap_backing *next; + static int num_left; + + /* allocate a page when required and hand out chunks */ + if (!next || !num_left) { + next = vmemmap_alloc_block(PAGE_SIZE, node); + if (unlikely(!next)) { + WARN_ON(1); + return NULL; + } + num_left = PAGE_SIZE / sizeof(struct vmemmap_backing); + } + + num_left--; + + return next++; +} + +static __meminit void vmemmap_list_populate(unsigned long phys, + unsigned long start, + int node) +{ + struct vmemmap_backing *vmem_back; + + vmem_back = vmemmap_list_alloc(node); + if (unlikely(!vmem_back)) { + WARN_ON(1); + return; + } + + vmem_back->phys = phys; + vmem_back->virt_addr = start; + vmem_back->list = vmemmap_list; + + vmemmap_list = vmem_back; +} + int __meminit vmemmap_populate(struct page *start_page, unsigned long nr_pages, int node) { @@ -276,6 +317,8 @@ int __meminit vmemmap_populate(struct page *start_page, if (!p) return -ENOMEM; + vmemmap_list_populate(__pa(p), start, node); + pr_debug(" * %016lx..%016lx allocated at %p\n", start, start + page_size, p); -- cgit v1.2.3