+ mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages.patch added to mm-unstable branch

+ mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/page_ext: init page_ext early if there are no deferred struct pages
has been added to the -mm mm-unstable branch.  Its filename is
     mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@soleen.com>
Subject: mm/page_ext: init page_ext early if there are no deferred struct pages
Date: Tue, 17 Jan 2023 20:46:17 +0000

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.

Link: https://lkml.kernel.org/r/20230117204617.1553748-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---


--- a/include/linux/page_ext.h~mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages
+++ a/include/linux/page_ext.h
@@ -55,6 +55,7 @@ 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);
--- a/init/main.c~mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages
+++ a/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_
 	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();
--- a/mm/page_alloc.c~mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages
+++ a/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(unsigne
 		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);
--- a/mm/page_ext.c~mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages
+++ a/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;
_

Patches currently in -mm which might be from pasha.tatashin@soleen.com are

mm-page_ext-do-not-allocate-space-for-page_ext-flags-if-not-needed.patch
mm-page_ext-init-page_ext-early-if-there-are-no-deferred-struct-pages.patch