From 19343b5bdd16ad4ae6b845ef829f68b683c4dfb5 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Mon, 13 May 2019 17:23:11 -0700 Subject: [PATCH] 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 --- include/linux/pagemap.h | 10 +--------- include/trace/events/writeback.h | 16 +++++++++++++++- mm/page-writeback.c | 12 ++++++++++++ 3 files changed, 28 insertions(+), 10 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 2e8438a1216a0..112f15bb5907d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -540,15 +540,7 @@ static inline int wait_on_page_locked_killable(struct page *page) extern void put_and_wait_on_page_locked(struct page *page); -/* - * Wait for a page to complete writeback - */ -static inline void wait_on_page_writeback(struct page *page) -{ - if (PageWriteback(page)) - wait_on_page_bit(page, PG_writeback); -} - +void wait_on_page_writeback(struct page *page); extern void end_page_writeback(struct page *page); void wait_for_stable_page(struct page *page); diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 32db72c7c055f..aa7f3aeac7408 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -53,7 +53,7 @@ WB_WORK_REASON struct wb_writeback_work; -TRACE_EVENT(writeback_dirty_page, +DECLARE_EVENT_CLASS(writeback_page_template, TP_PROTO(struct page *page, struct address_space *mapping), @@ -79,6 +79,20 @@ TRACE_EVENT(writeback_dirty_page, ) ); +DEFINE_EVENT(writeback_page_template, writeback_dirty_page, + + TP_PROTO(struct page *page, struct address_space *mapping), + + TP_ARGS(page, mapping) +); + +DEFINE_EVENT(writeback_page_template, wait_on_page_writeback, + + TP_PROTO(struct page *page, struct address_space *mapping), + + TP_ARGS(page, mapping) +); + DECLARE_EVENT_CLASS(writeback_dirty_inode_template, TP_PROTO(struct inode *inode, int flags), diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 9f61dfec6a1f6..07656485c0e61 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.