From: Yang Shi Date: Wed, 2 Jun 2021 03:53:01 +0000 (+1000) Subject: mm: rmap: make try_to_unmap() void function X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=54a08f5d889933f209bf434be310cd8e4c6df5e8;p=users%2Fjedix%2Flinux-maple.git mm: rmap: make try_to_unmap() void function Currently try_to_unmap() return bool value by checking page_mapcount(), however this may return false positive since page_mapcount() doesn't check all subpages of compound page. The total_mapcount() could be used instead, but its cost is higher since it traverses all subpages. Actually the most callers of try_to_unmap() don't care about the return value at all. So just need check if page is still mapped by page_mapped() when necessary. And page_mapped() does bail out early when it finds mapped subpage. Link: https://lkml.kernel.org/r/20210526201239.3351-2-shy828301@gmail.com Signed-off-by: Yang Shi Suggested-by: Hugh Dickins Acked-by: Hugh Dickins Acked-by: Minchan Kim Reviewed-by: Shakeel Butt Signed-off-by: Andrew Morton Signed-off-by: Stephen Rothwell --- diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 3a1ce4ef9276a..55a75cbb0f6cc 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -191,7 +191,7 @@ int page_referenced(struct page *, int is_locked, struct mem_cgroup *memcg, unsigned long *vm_flags); bool try_to_migrate(struct page *page, enum ttu_flags flags); -bool try_to_unmap(struct page *, enum ttu_flags flags); +void try_to_unmap(struct page *, enum ttu_flags flags); int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, unsigned long end, struct page **pages, diff --git a/mm/memory-failure.c b/mm/memory-failure.c index b88183a5107a1..a55409c1b5e74 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1206,7 +1206,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, enum ttu_flags ttu = TTU_IGNORE_MLOCK; struct address_space *mapping; LIST_HEAD(tokill); - bool unmap_success = true; + bool unmap_success; int kill = 1, forcekill; struct page *hpage = *hpagep; bool mlocked = PageMlocked(hpage); @@ -1269,7 +1269,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED); if (!PageHuge(hpage)) { - unmap_success = try_to_unmap(hpage, ttu); + try_to_unmap(hpage, ttu); } else { if (!PageAnon(hpage)) { /* @@ -1281,17 +1281,16 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn, */ mapping = hugetlb_page_mapping_lock_write(hpage); if (mapping) { - unmap_success = try_to_unmap(hpage, - ttu|TTU_RMAP_LOCKED); + try_to_unmap(hpage, ttu|TTU_RMAP_LOCKED); i_mmap_unlock_write(mapping); - } else { + } else pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn); - unmap_success = false; - } } else { - unmap_success = try_to_unmap(hpage, ttu); + try_to_unmap(hpage, ttu); } } + + unmap_success = !page_mapped(hpage); if (!unmap_success) pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n", pfn, page_mapcount(hpage)); diff --git a/mm/rmap.c b/mm/rmap.c index fe062f63ef4d8..79393a9804f43 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1658,9 +1658,10 @@ static int page_not_mapped(struct page *page) * Tries to remove all the page table entries which are mapping this * page, used in the pageout path. Caller must hold the page lock. * - * If unmap is successful, return true. Otherwise, false. + * It is the callers' responsibility to check if the page is still + * mapped when needed. */ -bool try_to_unmap(struct page *page, enum ttu_flags flags) +void try_to_unmap(struct page *page, enum ttu_flags flags) { struct rmap_walk_control rwc = { .rmap_one = try_to_unmap_one, @@ -1946,8 +1947,6 @@ bool try_to_migrate(struct page *page, enum ttu_flags flags) rmap_walk_locked(page, &rwc); else rmap_walk(page, &rwc); - - return !page_mapcount(page) ? true : false; } /* diff --git a/mm/vmscan.c b/mm/vmscan.c index d7c3cb8688dd4..abd610a526983 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1499,7 +1499,8 @@ static unsigned int shrink_page_list(struct list_head *page_list, if (unlikely(PageTransHuge(page))) flags |= TTU_SPLIT_HUGE_PMD; - if (!try_to_unmap(page, flags)) { + try_to_unmap(page, flags); + if (page_mapped(page)) { stat->nr_unmap_fail += nr_pages; if (!was_swapbacked && PageSwapBacked(page)) stat->nr_lazyfree_fail += nr_pages;