From 14455eabd8404a503dc8e80cd8ce185e96a94b22 Mon Sep 17 00:00:00 2001 From: Cheng Li Date: Fri, 9 Sep 2022 07:31:09 +0000 Subject: [PATCH] mm: use nth_page instead of mem_map_offset mem_map_next To handle the discontiguous case, mem_map_next() has a parameter named `offset`. As a function caller, one would be confused why "get next entry" needs a parameter named "offset". The other drawback of mem_map_next() is that the callers must take care of the map between parameter "iter" and "offset", otherwise we may get an hole or duplication during iteration. So we use nth_page instead of mem_map_next. And replace mem_map_offset with nth_page() per Matthew's comments. Link: https://lkml.kernel.org/r/1662708669-9395-1-git-send-email-lic121@chinatelecom.cn Signed-off-by: Cheng Li Fixes: 69d177c2fc70 ("hugetlbfs: handle pages higher order than MAX_ORDER") Reviewed-by: Matthew Wilcox (Oracle) Cc: Mike Kravetz Signed-off-by: Andrew Morton --- mm/hugetlb.c | 29 +++++++++++++++++------------ mm/internal.h | 28 ---------------------------- mm/memory.c | 21 ++++++++++----------- 3 files changed, 27 insertions(+), 51 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 008955d..6af1233 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1306,12 +1306,13 @@ static void __destroy_compound_gigantic_page(struct page *page, { int i; int nr_pages = 1 << order; - struct page *p = page + 1; + struct page *p; atomic_set(compound_mapcount_ptr(page), 0); atomic_set(compound_pincount_ptr(page), 0); - for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { + for (i = 1; i < nr_pages; i++) { + p = nth_page(page, i); p->mapping = NULL; clear_compound_head(p); if (!demote) @@ -1532,7 +1533,7 @@ static void add_hugetlb_page(struct hstate *h, struct page *page, static void __update_and_free_page(struct hstate *h, struct page *page) { int i; - struct page *subpage = page; + struct page *subpage; if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) return; @@ -1563,8 +1564,8 @@ static void __update_and_free_page(struct hstate *h, struct page *page) if (unlikely(PageHWPoison(page))) hugetlb_clear_page_hwpoison(page); - for (i = 0; i < pages_per_huge_page(h); - i++, subpage = mem_map_next(subpage, page, i)) { + for (i = 0; i < pages_per_huge_page(h); i++) { + subpage = nth_page(page, i); subpage->flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 1 << PG_dirty | 1 << PG_active | 1 << PG_private | @@ -1771,13 +1772,15 @@ static bool __prep_compound_gigantic_page(struct page *page, unsigned int order, { int i, j; int nr_pages = 1 << order; - struct page *p = page + 1; + struct page *p; /* we rely on prep_new_huge_page to set the destructor */ set_compound_order(page, order); __ClearPageReserved(page); __SetPageHead(page); - for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { + for (i = 1; i < nr_pages; i++) { + p = nth_page(page, i); + /* * For gigantic hugepages allocated through bootmem at * boot, it's safer to be consistent with the not-gigantic @@ -1824,14 +1827,16 @@ static bool __prep_compound_gigantic_page(struct page *page, unsigned int order, out_error: /* undo tail page modifications made above */ - p = page + 1; - for (j = 1; j < i; j++, p = mem_map_next(p, page, j)) { + for (j = 1; j < i; j++) { + p = nth_page(page, j); clear_compound_head(p); set_page_refcounted(p); } /* need to clear PG_reserved on remaining tail pages */ - for (; j < nr_pages; j++, p = mem_map_next(p, page, j)) + for (; j < nr_pages; j++) { + p = nth_page(page, j); __ClearPageReserved(p); + } set_compound_order(page, 0); #ifdef CONFIG_64BIT page[1].compound_nr = 0; @@ -6128,7 +6133,7 @@ static void record_subpages_vmas(struct page *page, struct vm_area_struct *vma, for (nr = 0; nr < refs; nr++) { if (likely(pages)) - pages[nr] = mem_map_offset(page, nr); + pages[nr] = nth_page(page, nr); if (vmas) vmas[nr] = vma; } @@ -6292,7 +6297,7 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, (vma->vm_end - ALIGN_DOWN(vaddr, PAGE_SIZE)) >> PAGE_SHIFT); if (pages || vmas) - record_subpages_vmas(mem_map_offset(page, pfn_offset), + record_subpages_vmas(nth_page(page, pfn_offset), vma, refs, likely(pages) ? pages + i : NULL, vmas ? vmas + i : NULL); diff --git a/mm/internal.h b/mm/internal.h index 0f106a3..e497ab1 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -638,34 +638,6 @@ static inline void vunmap_range_noflush(unsigned long start, unsigned long end) } #endif /* !CONFIG_MMU */ -/* - * Return the mem_map entry representing the 'offset' subpage within - * the maximally aligned gigantic page 'base'. Handle any discontiguity - * in the mem_map at MAX_ORDER_NR_PAGES boundaries. - */ -static inline struct page *mem_map_offset(struct page *base, int offset) -{ - if (unlikely(offset >= MAX_ORDER_NR_PAGES)) - return nth_page(base, offset); - return base + offset; -} - -/* - * Iterator over all subpages within the maximally aligned gigantic - * page 'base'. Handle any discontiguity in the mem_map. - */ -static inline struct page *mem_map_next(struct page *iter, - struct page *base, int offset) -{ - if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) { - unsigned long pfn = page_to_pfn(base) + offset; - if (!pfn_valid(pfn)) - return NULL; - return pfn_to_page(pfn); - } - return iter + 1; -} - /* Memory initialisation debug and verification */ enum mminit_level { MMINIT_WARNING, diff --git a/mm/memory.c b/mm/memory.c index d671ad3..c01c125 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5690,11 +5690,11 @@ static void clear_gigantic_page(struct page *page, unsigned int pages_per_huge_page) { int i; - struct page *p = page; + struct page *p; might_sleep(); - for (i = 0; i < pages_per_huge_page; - i++, p = mem_map_next(p, page, i)) { + for (i = 0; i < pages_per_huge_page; i++) { + p = nth_page(page, i); cond_resched(); clear_user_highpage(p, addr + i * PAGE_SIZE); } @@ -5730,13 +5730,12 @@ static void copy_user_gigantic_page(struct page *dst, struct page *src, struct page *dst_base = dst; struct page *src_base = src; - for (i = 0; i < pages_per_huge_page; ) { + for (i = 0; i < pages_per_huge_page; i++) { + dst = nth_page(dst_base, i); + src = nth_page(src_base, i); + cond_resched(); copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); - - i++; - dst = mem_map_next(dst, dst_base, i); - src = mem_map_next(src, src_base, i); } } @@ -5783,10 +5782,10 @@ long copy_huge_page_from_user(struct page *dst_page, void *page_kaddr; unsigned long i, rc = 0; unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; - struct page *subpage = dst_page; + struct page *subpage; - for (i = 0; i < pages_per_huge_page; - i++, subpage = mem_map_next(subpage, dst_page, i)) { + for (i = 0; i < pages_per_huge_page; i++) { + subpage = nth_page(dst_page, i); if (allow_pagefault) page_kaddr = kmap(subpage); else -- 2.7.4