From 19343b5bdd16ad4ae6b845ef829f68b683c4dfb5 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Mon, 13 May 2019 17:23:11 -0700 Subject: mm/page-writeback: introduce tracepoint for wait_on_page_writeback() Recently there have been some hung tasks on our server due to wait_on_page_writeback(), and we want to know the details of this PG_writeback, i.e. this page is writing back to which device. But it is not so convenient to get the details. I think it would be better to introduce a tracepoint for diagnosing the writeback details. Link: http://lkml.kernel.org/r/1556274402-19018-1-git-send-email-laoar.shao@gmail.com Signed-off-by: Yafang Shao Reviewed-by: Andrew Morton Cc: Jan Kara Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'mm') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 9f61dfec6a1f..07656485c0e6 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2808,6 +2808,18 @@ int __test_set_page_writeback(struct page *page, bool keep_write) } EXPORT_SYMBOL(__test_set_page_writeback); +/* + * Wait for a page to complete writeback + */ +void wait_on_page_writeback(struct page *page) +{ + if (PageWriteback(page)) { + trace_wait_on_page_writeback(page, page_mapping(page)); + wait_on_page_bit(page, PG_writeback); + } +} +EXPORT_SYMBOL_GPL(wait_on_page_writeback); + /** * wait_for_stable_page() - wait for writeback to finish, if necessary. * @page: The page to wait on. -- cgit