From 0ac5e785dcb797a3f0af1b205ce48134e186e88f Mon Sep 17 00:00:00 2001 From: Baoquan He Date: Mon, 25 Mar 2024 22:56:44 +0800 Subject: [PATCH] mm/mm_init.c: remove meaningless calculation of zone->managed_pages in free_area_init_core() Currently, in free_area_init_core(), when initialize zone's field, a rough value is set to zone->managed_pages. That value is calculated by (zone->present_pages - memmap_pages). In the meantime, add the value to nr_all_pages and nr_kernel_pages which represent all free pages of system (only low memory or including HIGHMEM memory separately). Both of them are gonna be used in alloc_large_system_hash(). However, the rough calculation and setting of zone->managed_pages is meaningless because a) memmap pages are allocated on units of node in sparse_init() or alloc_node_mem_map(pgdat); The simple (zone->present_pages - memmap_pages) is too rough to make sense for zone; b) the set zone->managed_pages will be zeroed out and reset with acutal value in mem_init() via memblock_free_all(). Before the resetting, no buddy allocation request is issued. Here, remove the meaningless and complicated calculation of (zone->present_pages - memmap_pages), directly set zone->managed_pages as zone->present_pages for now. It will be adjusted in mem_init(). And also remove the assignment of nr_all_pages and nr_kernel_pages in free_area_init_core(). Instead, call the newly added calc_nr_kernel_pages() to count up all free but not reserved memory in memblock and assign to nr_all_pages and nr_kernel_pages. The counting excludes memmap_pages, and other kernel used data, which is more accurate than old way and simpler, and can also cover the ppc required arch_reserved_kernel_pages() case. And also clean up the outdated code comment above free_area_init_core(). And free_area_init_core() is easy to understand now, no need to add words to explain. [bhe@redhat.com: initialize zone->managed_pages as zone->present_pages for now] Link: https://lkml.kernel.org/r/ZgU0bsJ2FEjykvju@MiWiFi-R3L-srv Link: https://lkml.kernel.org/r/20240325145646.1044760-5-bhe@redhat.com Signed-off-by: Baoquan He Reviewed-by: Mike Rapoport (IBM) Signed-off-by: Andrew Morton --- mm/mm_init.c | 46 +++++----------------------------------------- 1 file changed, 5 insertions(+), 41 deletions(-) diff --git a/mm/mm_init.c b/mm/mm_init.c index ae9149956497..b211b30231cb 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -1566,15 +1566,6 @@ void __ref free_area_init_core_hotplug(struct pglist_data *pgdat) } #endif -/* - * Set up the zone data structures: - * - mark all pages reserved - * - mark all memory queues empty - * - clear the memory bitmaps - * - * NOTE: pgdat should get zeroed by caller. - * NOTE: this function is only called during early init. - */ static void __init free_area_init_core(struct pglist_data *pgdat) { enum zone_type j; @@ -1585,41 +1576,13 @@ static void __init free_area_init_core(struct pglist_data *pgdat) for (j = 0; j < MAX_NR_ZONES; j++) { struct zone *zone = pgdat->node_zones + j; - unsigned long size, freesize, memmap_pages; - - size = zone->spanned_pages; - freesize = zone->present_pages; + unsigned long size = zone->spanned_pages; /* - * Adjust freesize so that it accounts for how much memory - * is used by this zone for memmap. This affects the watermark - * and per-cpu initialisations + * Initialize zone->managed_pages as 0 , it will be reset + * when memblock allocator frees pages into buddy system. */ - memmap_pages = calc_memmap_size(size, freesize); - if (!is_highmem_idx(j)) { - if (freesize >= memmap_pages) { - freesize -= memmap_pages; - if (memmap_pages) - pr_debug(" %s zone: %lu pages used for memmap\n", - zone_names[j], memmap_pages); - } else - pr_warn(" %s zone: %lu memmap pages exceeds freesize %lu\n", - zone_names[j], memmap_pages, freesize); - } - - if (!is_highmem_idx(j)) - nr_kernel_pages += freesize; - /* Charge for highmem memmap if there are enough kernel pages */ - else if (nr_kernel_pages > memmap_pages * 2) - nr_kernel_pages -= memmap_pages; - nr_all_pages += freesize; - - /* - * Set an approximate value for lowmem here, it will be adjusted - * when the bootmem allocator frees pages into the buddy system. - * And all highmem pages will be managed by the buddy system. - */ - zone_init_internals(zone, j, nid, freesize); + zone_init_internals(zone, j, nid, zone->present_pages); if (!size) continue; @@ -1916,6 +1879,7 @@ void __init free_area_init(unsigned long *max_zone_pfn) check_for_memory(pgdat); } + calc_nr_kernel_pages(); memmap_init(); /* disable hash distribution for systems with a single node */