From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Subject: mm, page_alloc: avoid page_to_pfn() in move_freepages() The start_pfn and end_pfn are already available in move_freepages_block(), there is no need to go back and forth between page and pfn in move_freepages and move_freepages_block, and pfn_valid_within() should validate pfn first before touching the page. Link: https://lkml.kernel.org/r/20210323131215.934472-1-liushixin2@xxxxxxxxxx Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx> Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-avoid-page_to_pfn-in-move_freepages +++ a/mm/page_alloc.c @@ -2431,19 +2431,21 @@ static inline struct page *__rmqueue_cma * boundary. If alignment is required, use move_freepages_block() */ static int move_freepages(struct zone *zone, - struct page *start_page, struct page *end_page, + unsigned long start_pfn, unsigned long end_pfn, int migratetype, int *num_movable) { struct page *page; + unsigned long pfn; unsigned int order; int pages_moved = 0; - for (page = start_page; page <= end_page;) { - if (!pfn_valid_within(page_to_pfn(page))) { - page++; + for (pfn = start_pfn; pfn <= end_pfn;) { + if (!pfn_valid_within(pfn)) { + pfn++; continue; } + page = pfn_to_page(pfn); if (!PageBuddy(page)) { /* * We assume that pages that could be isolated for @@ -2453,8 +2455,7 @@ static int move_freepages(struct zone *z if (num_movable && (PageLRU(page) || __PageMovable(page))) (*num_movable)++; - - page++; + pfn++; continue; } @@ -2464,7 +2465,7 @@ static int move_freepages(struct zone *z order = buddy_order(page); move_to_free_list(page, zone, order, migratetype); - page += 1 << order; + pfn += 1 << order; pages_moved += 1 << order; } @@ -2474,25 +2475,22 @@ static int move_freepages(struct zone *z int move_freepages_block(struct zone *zone, struct page *page, int migratetype, int *num_movable) { - unsigned long start_pfn, end_pfn; - struct page *start_page, *end_page; + unsigned long start_pfn, end_pfn, pfn; if (num_movable) *num_movable = 0; - start_pfn = page_to_pfn(page); - start_pfn = start_pfn & ~(pageblock_nr_pages-1); - start_page = pfn_to_page(start_pfn); - end_page = start_page + pageblock_nr_pages - 1; + pfn = page_to_pfn(page); + start_pfn = pfn & ~(pageblock_nr_pages - 1); end_pfn = start_pfn + pageblock_nr_pages - 1; /* Do not cross zone boundaries */ if (!zone_spans_pfn(zone, start_pfn)) - start_page = page; + start_pfn = pfn; if (!zone_spans_pfn(zone, end_pfn)) return 0; - return move_freepages(zone, start_page, end_page, migratetype, + return move_freepages(zone, start_pfn, end_pfn, migratetype, num_movable); } _
