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/include/asm/pgalloc-64.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/powerpc/include/asm/pgalloc-64.h') diff --git a/arch/powerpc/include/asm/pgalloc-64.h b/arch/powerpc/include/asm/pgalloc-64.h index 605f5c5398d1..292725cec2e3 100644 --- a/arch/powerpc/include/asm/pgalloc-64.h +++ b/arch/powerpc/include/asm/pgalloc-64.h @@ -11,6 +11,12 @@ #include #include +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 -- cgit v1.2.3