On Mon, Mar 25, 2024 at 10:56:44PM +0800, Baoquan He wrote: > 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), initialize zone->managed_pages as 0 > which reflect its actual value because no any page is added into buddy > system right now. It will be reset 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 And also clean up the outdated code comment above free_area_init_core().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. > > Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> Reviewed-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx> > --- > mm/mm_init.c | 46 +++++----------------------------------------- > 1 file changed, 5 insertions(+), 41 deletions(-)
