From 19343b5bdd16ad4ae6b845ef829f68b683c4dfb5 Mon Sep 17 00:00:00 2001
From: Yafang Shao <laoar.shao@gmail.com>
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 <laoar.shao@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
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.
--
2.30.2