[PATCH v1 1/3] mm: pass meminit_context to __free_pages_core()

[David Hildenbrand <david@xxxxxxxxxx>]

In preparation for further changes, let's teach __free_pages_core()
about the differences of memory hotplug handling.

Move the memory hotplug specific handling from generic_online_page() to
__free_pages_core(), use adjust_managed_page_count() on the memory
hotplug path, and spell out why memory freed via memblock
cannot currently use adjust_managed_page_count().

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 mm/internal.h       |  3 ++-
 mm/kmsan/init.c     |  2 +-
 mm/memory_hotplug.c |  9 +--------
 mm/mm_init.c        |  4 ++--
 mm/page_alloc.c     | 17 +++++++++++++++--
 5 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 12e95fdf61e90..3fdee779205ab 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -604,7 +604,8 @@ extern void __putback_isolated_page(struct page *page, 
unsigned int order,
                                    int mt);
 extern void memblock_free_pages(struct page *page, unsigned long pfn,
                                        unsigned int order);
-extern void __free_pages_core(struct page *page, unsigned int order);
+extern void __free_pages_core(struct page *page, unsigned int order,
+               enum meminit_context);
 
 /*
  * This will have no effect, other than possibly generating a warning, if the
diff --git a/mm/kmsan/init.c b/mm/kmsan/init.c
index 3ac3b8921d36f..ca79636f858e5 100644
--- a/mm/kmsan/init.c
+++ b/mm/kmsan/init.c
@@ -172,7 +172,7 @@ static void do_collection(void)
                shadow = smallstack_pop(&collect);
                origin = smallstack_pop(&collect);
                kmsan_setup_meta(page, shadow, origin, collect.order);
-               __free_pages_core(page, collect.order);
+               __free_pages_core(page, collect.order, MEMINIT_EARLY);
        }
 }
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 171ad975c7cfd..27e3be75edcf7 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -630,14 +630,7 @@ EXPORT_SYMBOL_GPL(restore_online_page_callback);
 
 void generic_online_page(struct page *page, unsigned int order)
 {
-       /*
-        * Freeing the page with debug_pagealloc enabled will try to unmap it,
-        * so we should map it first. This is better than introducing a special
-        * case in page freeing fast path.
-        */
-       debug_pagealloc_map_pages(page, 1 << order);
-       __free_pages_core(page, order);
-       totalram_pages_add(1UL << order);
+       __free_pages_core(page, order, MEMINIT_HOTPLUG);
 }
 EXPORT_SYMBOL_GPL(generic_online_page);
 
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 019193b0d8703..feb5b6e8c8875 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1938,7 +1938,7 @@ static void __init deferred_free_range(unsigned long pfn,
        for (i = 0; i < nr_pages; i++, page++, pfn++) {
                if (pageblock_aligned(pfn))
                        set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-               __free_pages_core(page, 0);
+               __free_pages_core(page, 0, MEMINIT_EARLY);
        }
 }
 
@@ -2513,7 +2513,7 @@ void __init memblock_free_pages(struct page *page, 
unsigned long pfn,
                }
        }
 
-       __free_pages_core(page, order);
+       __free_pages_core(page, order, MEMINIT_EARLY);
 }
 
 DEFINE_STATIC_KEY_MAYBE(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, init_on_alloc);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2224965ada468..e0c8a8354be36 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1214,7 +1214,8 @@ static void __free_pages_ok(struct page *page, unsigned 
int order,
        __count_vm_events(PGFREE, 1 << order);
 }
 
-void __free_pages_core(struct page *page, unsigned int order)
+void __free_pages_core(struct page *page, unsigned int order,
+               enum meminit_context context)
 {
        unsigned int nr_pages = 1 << order;
        struct page *p = page;
@@ -1234,7 +1235,19 @@ void __free_pages_core(struct page *page, unsigned int 
order)
        __ClearPageReserved(p);
        set_page_count(p, 0);
 
-       atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
+       if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG) &&
+           unlikely(context == MEMINIT_HOTPLUG)) {
+               /*
+                * Freeing the page with debug_pagealloc enabled will try to
+                * unmap it; some archs don't like double-unmappings, so
+                * map it first.
+                */
+               debug_pagealloc_map_pages(page, nr_pages);
+               adjust_managed_page_count(page, nr_pages);
+       } else {
+               /* memblock adjusts totalram_pages() ahead of time. */
+               atomic_long_add(nr_pages, &page_zone(page)->managed_pages);
+       }
 
        if (page_contains_unaccepted(page, order)) {
                if (order == MAX_PAGE_ORDER && __free_unaccepted(page))
-- 
2.45.1