powerpc: implement vmemmap_free()

vmemmap_free() does the opposite of vmemap_populate().
This patch also puts vmemmap_free() and vmemmap_list_free() into
 CONFIG_MEMMORY_HOTPLUG.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Acked-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 64 insertions, 21 deletions

diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 69203c8afb51..496379013873 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -298,6 +298,37 @@ static __meminit void vmemmap_list_populate(unsigned long phys,
         vmemmap_list = vmem_back;
 }
 
+int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
+{
+        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
+
+        /* Align to the page size of the linear mapping. */
+        start = _ALIGN_DOWN(start, page_size);
+
+        pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
+
+        for (; start < end; start += page_size) {
+                void *p;
+
+                if (vmemmap_populated(start, page_size))
+                        continue;
+
+                p = vmemmap_alloc_block(page_size, node);
+                if (!p)
+                        return -ENOMEM;
+
+                vmemmap_list_populate(__pa(p), start, node);
+
+                pr_debug("      * %016lx..%016lx allocated at %p\n",
+                         start, start + page_size, p);
+
+                vmemmap_create_mapping(start, page_size, __pa(p));
+        }
+
+        return 0;
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
 static unsigned long vmemmap_list_free(unsigned long start)
 {
         struct vmemmap_backing *vmem_back, *vmem_back_prev;
@@ -330,40 +361,52 @@ static unsigned long vmemmap_list_free(unsigned long start)
         return vmem_back->phys;
 }
 
-int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
+void __ref vmemmap_free(unsigned long start, unsigned long end)
 {
         unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
 
-        /* Align to the page size of the linear mapping. */
         start = _ALIGN_DOWN(start, page_size);
 
-        pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
+        pr_debug("vmemmap_free %lx...%lx\n", start, end);
 
         for (; start < end; start += page_size) {
-                void *p;
+                unsigned long addr;
 
+                /*
+                 * the section has already be marked as invalid, so
+                 * vmemmap_populated() true means some other sections still
+                 * in this page, so skip it.
+                 */
                 if (vmemmap_populated(start, page_size))
                         continue;
 
-                p = vmemmap_alloc_block(page_size, node);
-                if (!p)
-                        return -ENOMEM;
-
-                vmemmap_list_populate(__pa(p), start, node);
-
-                pr_debug("      * %016lx..%016lx allocated at %p\n",
-                         start, start + page_size, p);
-
-                vmemmap_create_mapping(start, page_size, __pa(p));
+                addr = vmemmap_list_free(start);
+                if (addr) {
+                        struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
+
+                        if (PageReserved(page)) {
+                                /* allocated from bootmem */
+                                if (page_size < PAGE_SIZE) {
+                                        /*
+                                         * this shouldn't happen, but if it is
+                                         * the case, leave the memory there
+                                         */
+                                        WARN_ON_ONCE(1);
+                                } else {
+                                        unsigned int nr_pages =
+                                                1 << get_order(page_size);
+                                        while (nr_pages--)
+                                                free_reserved_page(page++);
+                                }
+                        } else
+                                free_pages((unsigned long)(__va(addr)),
+                                                        get_order(page_size));
+
+                        vmemmap_remove_mapping(start, page_size);
+                }
         }
-
-        return 0;
-}
-
-void vmemmap_free(unsigned long start, unsigned long end)
-{
 }
-
+#endif
 void register_page_bootmem_memmap(unsigned long section_nr,
                                   struct page *start_page, unsigned long size)
 {