From: Muchun Song Date: Fri, 19 Aug 2022 03:55:32 +0000 (+0800) Subject: mm: hugetlb_vmemmap: simplify reset_struct_pages() X-Git-Tag: v6.1-rc1~68^2~485 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=33febb519d673b9f574903764f13f47e65328ca5;p=thirdparty%2Flinux.git mm: hugetlb_vmemmap: simplify reset_struct_pages() We can choose to copy three contiguous tail pages' content to the first three pages instead of copying one by one to simplify the code and reduce code size from 229 bytes to 63 bytes. The BUILD_BUG_ON() aims to avoid out-of-bounds accesses. Link: https://lkml.kernel.org/r/20220819035532.6189-1-songmuchun@bytedance.com Signed-off-by: Muchun Song Reviewed-by: Miaohe Lin Cc: Mike Kravetz Signed-off-by: Andrew Morton --- diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 76b2d03a0d8dd..ba2a2596fb4e8 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -265,11 +265,10 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, static inline void reset_struct_pages(struct page *start) { - int i; struct page *from = start + NR_RESET_STRUCT_PAGE; - for (i = 0; i < NR_RESET_STRUCT_PAGE; i++) - memcpy(start + i, from, sizeof(*from)); + BUILD_BUG_ON(NR_RESET_STRUCT_PAGE * 2 > PAGE_SIZE / sizeof(struct page)); + memcpy(start, from, sizeof(*from) * NR_RESET_STRUCT_PAGE); } static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,