The patch titled
Subject: mm/page-writeback: introduce tracepoint for wait_on_page_writeback()
has been added to the -mm tree. Its filename is
mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Yafang Shao <laoar.shao@xxxxxxxxx>
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@xxxxxxxxx
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagemap.h | 10 +---------
include/trace/events/writeback.h | 16 +++++++++++++++-
mm/page-writeback.c | 12 ++++++++++++
3 files changed, 28 insertions(+), 10 deletions(-)
--- a/include/linux/pagemap.h~mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback
+++ a/include/linux/pagemap.h
@@ -540,15 +540,7 @@ static inline int wait_on_page_locked_ki
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);
--- a/include/trace/events/writeback.h~mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback
+++ a/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),
--- a/mm/page-writeback.c~mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback
+++ a/mm/page-writeback.c
@@ -2808,6 +2808,18 @@ int __test_set_page_writeback(struct pag
}
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.
_
Patches currently in -mm which might be from laoar.shao@xxxxxxxxx are
mm-vmscan-drop-zone-id-from-kswapd-tracepoints.patch
mm-compaction-show-gfp-flag-names-in-try_to_compact_pages-tracepoint.patch
mm-compaction-some-tracepoints-should-be-defined-only-when-config_compaction-is-set.patch
mm-vmscan-add-tracepoints-for-node-reclaim.patch
mm-vmscan-drop-may_writepage-and-classzone_idx-from-direct-reclaim-begin-template.patch
mm-page_alloc-remove-unnecessary-parameter-in-rmqueue_pcplist.patch
mm-vmscan-dont-disable-irq-again-when-count-pgrefill-for-memcg.patch
mm-vmscan-simplify-trace_reclaim_flags-and-trace_shrink_flags.patch
mm-page-writeback-introduce-tracepoint-for-wait_on_page_writeback.patch
