On 1/18/23 16:52, Pasha Tatashin wrote:
> page_ext must be initialized after all struct pages are initialized.
> Therefore, page_ext is initialized after page_alloc_init_late(), and
> can optionally be initialized earlier via early_page_ext kernel
> parameter which as a side effect also disables deferred struct pages.
>
> Allow to automatically init page_ext early when there are no deferred
> struct pages in order to be able to use page_ext during kernel boot
> and track for example page allocations early.
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> include/linux/page_ext.h | 2 ++
> init/main.c | 6 +++---
> mm/page_alloc.c | 6 +++++-
> mm/page_ext.c | 2 +-
> 4 files changed, 11 insertions(+), 5 deletions(-)
>
> Changelog:
> v2: Fixed build issue with CONFIG_PAGE_EXTENSION=n
>
> diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
> index 67314f648aeb..bc2e39090a1f 100644
> --- a/include/linux/page_ext.h
> +++ b/include/linux/page_ext.h
> @@ -29,6 +29,8 @@ struct page_ext_operations {
> bool need_shared_flags;
> };
>
> +extern bool deferred_struct_pages;
> +
> #ifdef CONFIG_PAGE_EXTENSION
>
> /*
> diff --git a/init/main.c b/init/main.c
> index e1c3911d7c70..64cd2ff051c4 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -855,8 +855,8 @@ static void __init mm_init(void)
> pgtable_init();
> debug_objects_mem_init();
> vmalloc_init();
> - /* Should be run after vmap initialization */
> - if (early_page_ext_enabled())
> + /* If no deferred init page_ext now, as vmap is fully initialized */
> + if (!deferred_struct_pages)
> page_ext_init();
> /* Should be run before the first non-init thread is created */
> init_espfix_bsp();
> @@ -1628,7 +1628,7 @@ static noinline void __init kernel_init_freeable(void)
> padata_init();
> page_alloc_init_late();
> /* Initialize page ext after all struct pages are initialized. */
> - if (!early_page_ext_enabled())
> + if (deferred_struct_pages)
> page_ext_init();
>
> do_basic_setup();
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 99ebb08dc3f2..717f12e83b85 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -430,6 +430,8 @@ EXPORT_SYMBOL(nr_online_nodes);
>
> int page_group_by_mobility_disabled __read_mostly;
>
> +bool deferred_struct_pages __meminitdata;
> +
> #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
> /*
> * During boot we initialize deferred pages on-demand, as needed, but once
> @@ -6803,8 +6805,10 @@ void __meminit memmap_init_range(unsigned long size, int nid, unsigned long zone
> if (context == MEMINIT_EARLY) {
> if (overlap_memmap_init(zone, &pfn))
> continue;
> - if (defer_init(nid, pfn, zone_end_pfn))
> + if (defer_init(nid, pfn, zone_end_pfn)) {
> + deferred_struct_pages = true;
> break;
> + }
> }
>
> page = pfn_to_page(pfn);
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index e2c22ffdbb81..dc1626be458b 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -92,7 +92,7 @@ unsigned long page_ext_size;
> static unsigned long total_usage;
> static struct page_ext *lookup_page_ext(const struct page *page);
>
> -bool early_page_ext;
> +bool early_page_ext __meminitdata;
> static int __init setup_early_page_ext(char *str)
> {
> early_page_ext = true;
