The template path still has a local opt-out predicate for the page_ref_set tracepoint and keeps a non-template fallback path. This makes the code more complex without a strong reason to keep the separate path.
Use the template path unconditionally after the corresponding seed page has been initialized: the first head page seeds the head template, and the first tail page in each compound range seeds the tail template. This keeps the first-page seeding logic unchanged, but removes the extra non-template fallback from the main loops. This also means sanitized builds no longer force this path back to the per-page initialization stores, and an enabled page_ref_set tracepoint will no longer observe every ZONE_DEVICE initialization-time refcount assignment. That tradeoff is intentional: this code is still initializing struct pages before they are handed out, and keeping those local debug special cases would preserve a separate initialization-only path while making the common code more complex. Suggested-by: Muchun Song <[email protected]> Signed-off-by: Li Zhe <[email protected]> --- mm/mm_init.c | 36 ++++-------------------------------- 1 file changed, 4 insertions(+), 32 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index 2a723a518f41..ae42a1311e1d 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1065,25 +1065,6 @@ static void __ref zone_device_page_init_slow(struct page *page, set_page_count(page, 0); } -static inline bool zone_device_page_init_optimization_enabled(void) -{ - /* - * Keep sanitized builds on the slow path so their stores stay - * instrumented. - */ - if (IS_ENABLED(CONFIG_KASAN) || IS_ENABLED(CONFIG_KMSAN)) - return false; - - /* - * The template fast path copies a preinitialized struct page image. - * Skip it when the page_ref_set tracepoint is enabled. - */ - if (page_ref_tracepoint_active(page_ref_set)) - return false; - - return true; -} - static inline void zone_device_tail_page_init(struct page *page, unsigned long pfn, unsigned long zone_idx, int nid, struct dev_pagemap *pgmap, const struct page *head, @@ -1151,8 +1132,7 @@ static void __ref memmap_init_compound(struct page *head, unsigned long head_pfn, unsigned long zone_idx, int nid, struct dev_pagemap *pgmap, - unsigned long nr_pages, - bool use_template) + unsigned long nr_pages) { unsigned long pfn, end_pfn = head_pfn + nr_pages; unsigned int order = pgmap->vmemmap_shift; @@ -1169,10 +1149,7 @@ static void __ref memmap_init_compound(struct page *head, for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) { struct page *page = pfn_to_page(pfn); - if (!use_template) { - zone_device_tail_page_init(page, pfn, zone_idx, nid, - pgmap, head, order); - } else if (pfn == head_pfn + 1) { + if (pfn == head_pfn + 1) { /* * All tails of the same compound page share the * state established by prep_compound_tail(). Reuse @@ -1197,7 +1174,6 @@ void __ref memmap_init_zone_device(struct zone *zone, unsigned long nr_pages, struct dev_pagemap *pgmap) { - bool use_template = zone_device_page_init_optimization_enabled(); unsigned long pfn, end_pfn = start_pfn + nr_pages; struct pglist_data *pgdat = zone->zone_pgdat; struct vmem_altmap *altmap = pgmap_altmap(pgmap); @@ -1223,10 +1199,7 @@ void __ref memmap_init_zone_device(struct zone *zone, for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) { struct page *page = pfn_to_page(pfn); - if (!use_template) { - zone_device_page_init_slow(page, pfn, zone_idx, - nid, pgmap); - } else if (pfn == start_pfn) { + if (pfn == start_pfn) { /* * Seed the reusable head-page template from the * first real struct page, because the existing @@ -1249,8 +1222,7 @@ void __ref memmap_init_zone_device(struct zone *zone, continue; memmap_init_compound(page, pfn, zone_idx, nid, pgmap, - compound_nr_pages(pfn, altmap, pgmap), - use_template); + compound_nr_pages(pfn, altmap, pgmap)); } pageblock_migratetype_init_range(start_pfn, nr_pages, MIGRATE_MOVABLE); -- 2.20.1
