diff mbox series

mm/page_ext: init page_ext early if there are no deferred struct pages

Message ID 20230117204617.1553748-1-pasha.tatashin@soleen.com
State New
Headers
Series mm/page_ext: init page_ext early if there are no deferred struct pages |

Commit Message

Pasha Tatashin Jan. 17, 2023, 8:46 p.m. UTC 
  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@soleen.com>
---
 include/linux/page_ext.h | 1 +
 init/main.c              | 6 +++---
 mm/page_alloc.c          | 6 +++++-
 mm/page_ext.c            | 2 +-
 4 files changed, 10 insertions(+), 5 deletions(-)

Comments

Andrew Morton Jan. 18, 2023, 1:13 a.m. UTC | #1 
On Tue, 17 Jan 2023 20:46:17 +0000 Pasha Tatashin <pasha.tatashin@soleen.com> 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.

Compilation blows up with CONFIG_PAGE_EXTENSION=n.  I did

--- a/include/linux/page_ext.h~mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages-fix
+++ a/include/linux/page_ext.h
@@ -92,6 +92,7 @@ static inline struct page_ext *page_ext_
 
 #else /* !CONFIG_PAGE_EXTENSION */
 struct page_ext;
+#define deferred_struct_pages (0)
 
 static inline bool early_page_ext_enabled(void)
 {

but it then blew up differently.
Pasha Tatashin Jan. 18, 2023, 3:01 p.m. UTC | #2 
On Tue, Jan 17, 2023 at 8:13 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 17 Jan 2023 20:46:17 +0000 Pasha Tatashin <pasha.tatashin@soleen.com> 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.
>
> Compilation blows up with CONFIG_PAGE_EXTENSION=n.  I did

Thanks, I will update the patch and send it soon.

Pasha
diff mbox series

Patch

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 22be4582faae..1e9bcc37a342 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -36,6 +36,7 @@  struct page_ext {
 	unsigned long flags;
 };
 
+extern bool deferred_struct_pages;
 extern bool early_page_ext;
 extern unsigned long page_ext_size;
 extern void pgdat_page_ext_init(struct pglist_data *pgdat);
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 0745aedebb37..5a3e0f00f31d 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
@@ -6761,8 +6763,10 @@  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 4ee522fd381c..918e2e131ab0 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -91,7 +91,7 @@  unsigned long page_ext_size = sizeof(struct page_ext);
 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;