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Commit 19343b5b authored by Yafang Shao's avatar Yafang Shao Committed by Linus Torvalds
Browse files

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: default avatarYafang Shao <laoar.shao@gmail.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 60b62ff7

include/linux/pagemap.h

+1 −9
Original line number Diff line number Diff line
@@ -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);

include/trace/events/writeback.h

+15 −1
Original line number Diff line number Diff line
@@ -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),

mm/page-writeback.c

+12 −0
Original line number Diff line number Diff line
@@ -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.