From ef18a1ca847b01cb7296f11a728cb2f5ef671760 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 18 Oct 2019 20:20:36 -0700 Subject: [PATCH] mm/thp: allow dropping THP from page cache Once a THP is added to the page cache, it cannot be dropped via /proc/sys/vm/drop_caches. Fix this issue with proper handling in invalidate_mapping_pages(). Link: http://lkml.kernel.org/r/20191017164223.2762148-5-songliubraving@fb.com Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Signed-off-by: Kirill A. Shutemov Signed-off-by: Song Liu Tested-by: Song Liu Acked-by: Yang Shi Cc: Matthew Wilcox (Oracle) Cc: Oleg Nesterov Cc: Srikar Dronamraju Cc: William Kucharski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/truncate.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/truncate.c b/mm/truncate.c index 8563339041f6..dd9ebc1da356 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -592,6 +592,16 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, unlock_page(page); continue; } + + /* Take a pin outside pagevec */ + get_page(page); + + /* + * Drop extra pins before trying to invalidate + * the huge page. + */ + pagevec_remove_exceptionals(&pvec); + pagevec_release(&pvec); } ret = invalidate_inode_page(page); @@ -602,6 +612,8 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, */ if (!ret) deactivate_file_page(page); + if (PageTransHuge(page)) + put_page(page); count += ret; } pagevec_remove_exceptionals(&pvec);