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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>
This commit is contained in:
Yafang Shao 2019-05-13 17:23:11 -07:00 committed by Linus Torvalds
parent 60b62ff7cc
commit 19343b5bdd
3 changed files with 28 additions and 10 deletions
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10
include/linux/pagemap.h
View File

@ -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);

16
include/trace/events/writeback.h
View File

@ -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),

12
mm/page-writeback.c
View File

@ -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.