From abef6d264d2413a625670bdb873133576d5cce5f Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Tue, 31 May 2022 09:20:51 -0400 Subject: [PATCH] mm/page_alloc: Reduce potential fragmentation in make_alloc_exact() Try to avoid using the left over split page on the next request for a page by calling __free_pages_ok() with FPI_TO_TAIL. This increases the potential of defragmenting memory when it's used for a short period of time. Suggested-by: Matthew Wilcox (Oracle) Signed-off-by: Liam R. Howlett --- mm/page_alloc.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f01c71e41bcf..8b6d6cada684 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5580,14 +5580,18 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order, size_t size) { if (addr) { - unsigned long alloc_end = addr + (PAGE_SIZE << order); - unsigned long used = addr + PAGE_ALIGN(size); - - split_page(virt_to_page((void *)addr), order); - while (used < alloc_end) { - free_page(used); - used += PAGE_SIZE; - } + unsigned long nr = DIV_ROUND_UP(size, PAGE_SIZE); + struct page *page = virt_to_page((void *)addr); + struct page *last = page + nr; + + split_page_owner(page, 1 << order); + split_page_memcg(page, 1 << order); + while (page < --last) + set_page_refcounted(last); + + last = page + (1UL << order); + for (page += nr; page < last; page++) + __free_pages_ok(page, 0, FPI_TO_TAIL); } return (void *)addr; } -- 2.35.1