bootmem: stop using page->index

Encode the type into the bottom four bits of page->private and the info
into the remaining bits.  Also turn the bootmem type into a named enum.

Link: https://lkml.kernel.org/r/20241005200121.3231142-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ff253648706fa9cd49169a54882014a72ad540cf..4d5fde32413613aff8de32097434945237909daa 100644 (file)
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -987,13 +987,12 @@ int arch_add_memory(int nid, u64 start, u64 size,
 
 static void __meminit free_pagetable(struct page *page, int order)
 {
-       unsigned long magic;
-       unsigned int nr_pages = 1 << order;
-
        /* bootmem page has reserved flag */
        if (PageReserved(page)) {
-               magic = page->index;
-               if (magic == SECTION_INFO || magic == MIX_SECTION_INFO) {
+               enum bootmem_type type = bootmem_type(page);
+               unsigned long nr_pages = 1 << order;
+
+               if (type == SECTION_INFO || type == MIX_SECTION_INFO) {
                        while (nr_pages--)
                                put_page_bootmem(page++);
                } else

diff --git a/include/linux/bootmem_info.h b/include/linux/bootmem_info.h
index cffa38a73618fe0b451af9859116d54ae8b0df04..e2fe5de93dcc9aa786af67fa50f1969116dd5b4b 100644 (file)
--- a/include/linux/bootmem_info.h
+++ b/include/linux/bootmem_info.h
@@ -6,11 +6,10 @@
 #include <linux/kmemleak.h>
 
 /*
- * Types for free bootmem stored in page->lru.next. These have to be in
- * some random range in unsigned long space for debugging purposes.
+ * Types for free bootmem stored in the low bits of page->private.
  */
-enum {
-       MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE = 12,
+enum bootmem_type {
+       MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE = 1,
        SECTION_INFO = MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE,
        MIX_SECTION_INFO,
        NODE_INFO,
@@ -21,9 +20,19 @@ enum {
 void __init register_page_bootmem_info_node(struct pglist_data *pgdat);
 
 void get_page_bootmem(unsigned long info, struct page *page,
-                     unsigned long type);
+               enum bootmem_type type);
 void put_page_bootmem(struct page *page);
 
+static inline enum bootmem_type bootmem_type(const struct page *page)
+{
+       return (unsigned long)page->private & 0xf;
+}
+
+static inline unsigned long bootmem_info(const struct page *page)
+{
+       return (unsigned long)page->private >> 4;
+}
+
 /*
  * Any memory allocated via the memblock allocator and not via the
  * buddy will be marked reserved already in the memmap. For those
@@ -31,7 +40,7 @@ void put_page_bootmem(struct page *page);
  */
 static inline void free_bootmem_page(struct page *page)
 {
-       unsigned long magic = page->index;
+       enum bootmem_type type = bootmem_type(page);
 
        /*
         * The reserve_bootmem_region sets the reserved flag on bootmem
@@ -39,7 +48,7 @@ static inline void free_bootmem_page(struct page *page)
         */
        VM_BUG_ON_PAGE(page_ref_count(page) != 2, page);
 
-       if (magic == SECTION_INFO || magic == MIX_SECTION_INFO)
+       if (type == SECTION_INFO || type == MIX_SECTION_INFO)
                put_page_bootmem(page);
        else
                VM_BUG_ON_PAGE(1, page);
@@ -54,7 +63,7 @@ static inline void put_page_bootmem(struct page *page)
 }
 
 static inline void get_page_bootmem(unsigned long info, struct page *page,
-                                   unsigned long type)
+                                   enum bootmem_type type)
 {
 }
 

diff --git a/mm/bootmem_info.c b/mm/bootmem_info.c
index fa7cb0c87c03f7e5691d883c2e57010dc50d056d..95f288169a380d005e877d7cb144538316b5a59c 100644 (file)
--- a/mm/bootmem_info.c
+++ b/mm/bootmem_info.c
@@ -14,23 +14,24 @@
 #include <linux/memory_hotplug.h>
 #include <linux/kmemleak.h>
 
-void get_page_bootmem(unsigned long info, struct page *page, unsigned long type)
+void get_page_bootmem(unsigned long info, struct page *page,
+               enum bootmem_type type)
 {
-       page->index = type;
+       BUG_ON(type > 0xf);
+       BUG_ON(info > (ULONG_MAX >> 4));
        SetPagePrivate(page);
-       set_page_private(page, info);
+       set_page_private(page, info << 4 | type);
        page_ref_inc(page);
 }
 
 void put_page_bootmem(struct page *page)
 {
-       unsigned long type = page->index;
+       enum bootmem_type type = bootmem_type(page);
 
        BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
               type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 
        if (page_ref_dec_return(page) == 1) {
-               page->index = 0;
                ClearPagePrivate(page);
                set_page_private(page, 0);
                INIT_LIST_HEAD(&page->lru);

diff --git a/mm/sparse.c b/mm/sparse.c
index dc38539f85603bde022e7d6fd16ed8c0d0483861..6ba5354cf2e117e5f19221fc8caff38779b5cc93 100644 (file)
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -720,19 +720,19 @@ static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
 static void free_map_bootmem(struct page *memmap)
 {
        unsigned long maps_section_nr, removing_section_nr, i;
-       unsigned long magic, nr_pages;
+       unsigned long type, nr_pages;
        struct page *page = virt_to_page(memmap);
 
        nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
                >> PAGE_SHIFT;
 
        for (i = 0; i < nr_pages; i++, page++) {
-               magic = page->index;
+               type = bootmem_type(page);
 
-               BUG_ON(magic == NODE_INFO);
+               BUG_ON(type == NODE_INFO);
 
                maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
-               removing_section_nr = page_private(page);
+               removing_section_nr = bootmem_info(page);
 
                /*
                 * When this function is called, the removing section is