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

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.

[pasha.tatashin@soleen.com: fix build with CONFIG_PAGE_EXTENSION=n]
Link: https://lkml.kernel.org/r/20230118155251.2522985-1-pasha.tatashin@soleen.com
Link: https://lkml.kernel.org/r/20230117204617.1553748-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 67314f648aeba5aa1ca5f13e78386e3d22216370..bc2e39090a1f50453fe76aa544404eb531009d11 100644 (file)
--- 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 e1c3911d7c707d8a864b9a06b12184e58dcb49a8..64cd2ff051c429de760ee1450ed42f7bac0adf22 100644 (file)
--- 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 0cfad30fb44ce51bcc38b6ef13830b44afaf3929..ecb9e9acfe7f96860109bca1a94c8cc635c44a1d 100644 (file)
--- 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 e2c22ffdbb814593fe7a5b331edd8b471bf700a8..dc1626be458bffb50ee1fbe19b7f979fc21e9076 100644 (file)
--- 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;