===================================================================
@@ -11,6 +11,12 @@
#include <linux/cpumask.h>
#include <linux/percpu.h>
+struct vmemmap_backing {
+ struct vmemmap_backing *list;
+ unsigned long phys;
+ unsigned long virt_addr;
+};
+
/*
* Functions that deal with pagetables that could be at any level of
* the table need to be passed an "index_size" so they know how to
===================================================================
@@ -252,6 +252,47 @@ static void __meminit vmemmap_create_map
}
#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 pa
if (!p)
return -ENOMEM;
+ vmemmap_list_populate(__pa(p), start, node);
+
pr_debug(" * %016lx..%016lx allocated at %p\n",
start, start + page_size, p);
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 <markn@au1.ibm.com> --- changes since v2: - use a pointer to the next struct vmemmap_backing instead of an hlist - add vmemmap_list_alloc() to allocate space for vmemmap_backing structs a page at-a-time when needed changes since v1: - use an hlist to save space in the structure - remove the spinlock because it's not needed arch/powerpc/include/asm/pgalloc-64.h | 6 ++++ arch/powerpc/mm/init_64.c | 43 ++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+)