From 13c526540b316937a16946e75d459e011be0ce2e Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 7 Jun 2024 11:09:36 +0200 Subject: [PATCH] mm: pass meminit_context to __free_pages_core() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Patch series "mm/memory_hotplug: use PageOffline() instead of PageReserved() for !ZONE_DEVICE". This can be a considered a long-overdue follow-up to some parts of [1]. The patches are based on [2], but they are not strictly required -- just makes it clearer why we can use adjust_managed_page_count() for memory hotplug without going into details about highmem. We stop initializing pages with PageReserved() in memory hotplug code -- except when dealing with ZONE_DEVICE for now. Instead, we use PageOffline(): all pages are initialized to PageOffline() when onlining a memory section, and only the ones actually getting exposed to the system/page allocator will get PageOffline cleared. This way, we enlighten memory hotplug more about PageOffline() pages and can cleanup some hacks we have in virtio-mem code. What about ZONE_DEVICE? PageOffline() is wrong, but we might just stop using PageReserved() for them later by simply checking for is_zone_device_page() at suitable places. That will be a separate patch set / proposal. This primarily affects virtio-mem, HV-balloon and XEN balloon. I only briefly tested with virtio-mem, which benefits most from these cleanups. [1] https://lore.kernel.org/all/20191024120938.11237-1-david@redhat.com/ [2] https://lkml.kernel.org/r/20240607083711.62833-1-david@redhat.com This patch (of 3): 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(). [david@redhat.com: add missed CONFIG_DEFERRED_STRUCT_PAGE_INIT] Link: https://lkml.kernel.org/r/b72e6efd-fb0a-459c-b1a0-88a98e5b19e2@redhat.com [david@redhat.com: fix up the memblock comment, per Oscar] Link: https://lkml.kernel.org/r/2ed64218-7f3b-4302-a5dc-27f060654fe2@redhat.com [david@redhat.com: add the parameter name also in the declaration] Link: https://lkml.kernel.org/r/ca575956-f0dd-4fb9-a307-6b7621681ed9@redhat.com Link: https://lkml.kernel.org/r/20240607090939.89524-1-david@redhat.com Link: https://lkml.kernel.org/r/20240607090939.89524-2-david@redhat.com Signed-off-by: David Hildenbrand Cc: Alexander Potapenko Cc: Dexuan Cui Cc: Dmitry Vyukov Cc: Eugenio Pérez Cc: Haiyang Zhang Cc: Jason Wang Cc: Juergen Gross Cc: "K. Y. Srinivasan" Cc: Marco Elver Cc: Michael S. Tsirkin Cc: Mike Rapoport (IBM) Cc: Oleksandr Tyshchenko Cc: Oscar Salvador Cc: Stefano Stabellini Cc: Wei Liu Cc: Xuan Zhuo Signed-off-by: Andrew Morton --- mm/internal.h | 3 ++- mm/kmsan/init.c | 2 +- mm/memory_hotplug.c | 9 +-------- mm/mm_init.c | 6 +++--- mm/page_alloc.c | 17 +++++++++++++++-- 5 files changed, 22 insertions(+), 15 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 34217cf4514d..0af4c9885424 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 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 3ac3b8921d36..ca79636f858e 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 f7580ec80538..e5aafed2b9ce 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 5d150d412920..03874f624b32 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1931,7 +1931,7 @@ static void __init deferred_free_pages(unsigned long pfn, if (nr_pages == MAX_ORDER_NR_PAGES && IS_MAX_ORDER_ALIGNED(pfn)) { for (i = 0; i < nr_pages; i += pageblock_nr_pages) set_pageblock_migratetype(page + i, MIGRATE_MOVABLE); - __free_pages_core(page, MAX_PAGE_ORDER); + __free_pages_core(page, MAX_PAGE_ORDER, MEMINIT_EARLY); return; } @@ -1941,7 +1941,7 @@ static void __init deferred_free_pages(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); } } @@ -2471,7 +2471,7 @@ 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 8d7b4424b645..8c6b4ba62ac1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1219,7 +1219,8 @@ 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; @@ -1239,7 +1240,19 @@ 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() manually. */ + atomic_long_add(nr_pages, &page_zone(page)->managed_pages); + } if (page_contains_unaccepted(page, order)) { if (order == MAX_PAGE_ORDER && __free_unaccepted(page))