From 3a8e9ac89e6a5106cfb6b85d4c9cf9bfa3519bc7 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 29 Aug 2019 15:47:19 -0700 Subject: writeback: add tracepoints for cgroup foreign writebacks cgroup foreign inode handling has quite a bit of heuristics and internal states which sometimes makes it difficult to understand what's going on. Add tracepoints to improve visibility. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- include/trace/events/writeback.h | 123 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) (limited to 'include/trace/events/writeback.h') diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index aa7f3aeac740..3dc9fb9e7c78 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -176,6 +176,129 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w #endif /* CONFIG_CGROUP_WRITEBACK */ #endif /* CREATE_TRACE_POINTS */ +#ifdef CONFIG_CGROUP_WRITEBACK +TRACE_EVENT(inode_foreign_history, + + TP_PROTO(struct inode *inode, struct writeback_control *wbc, + unsigned int history), + + TP_ARGS(inode, wbc, history), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, ino) + __field(unsigned int, cgroup_ino) + __field(unsigned int, history) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(inode_to_bdi(inode)->dev), 32); + __entry->ino = inode->i_ino; + __entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc); + __entry->history = history; + ), + + TP_printk("bdi %s: ino=%lu cgroup_ino=%u history=0x%x", + __entry->name, + __entry->ino, + __entry->cgroup_ino, + __entry->history + ) +); + +TRACE_EVENT(inode_switch_wbs, + + TP_PROTO(struct inode *inode, struct bdi_writeback *old_wb, + struct bdi_writeback *new_wb), + + TP_ARGS(inode, old_wb, new_wb), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, ino) + __field(unsigned int, old_cgroup_ino) + __field(unsigned int, new_cgroup_ino) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(old_wb->bdi->dev), 32); + __entry->ino = inode->i_ino; + __entry->old_cgroup_ino = __trace_wb_assign_cgroup(old_wb); + __entry->new_cgroup_ino = __trace_wb_assign_cgroup(new_wb); + ), + + TP_printk("bdi %s: ino=%lu old_cgroup_ino=%u new_cgroup_ino=%u", + __entry->name, + __entry->ino, + __entry->old_cgroup_ino, + __entry->new_cgroup_ino + ) +); + +TRACE_EVENT(track_foreign_dirty, + + TP_PROTO(struct page *page, struct bdi_writeback *wb), + + TP_ARGS(page, wb), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(u64, bdi_id) + __field(unsigned long, ino) + __field(unsigned int, memcg_id) + __field(unsigned int, cgroup_ino) + __field(unsigned int, page_cgroup_ino) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->bdi_id = wb->bdi->id; + __entry->ino = page->mapping->host->i_ino; + __entry->memcg_id = wb->memcg_css->id; + __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); + __entry->page_cgroup_ino = page->mem_cgroup->css.cgroup->kn->id.ino; + ), + + TP_printk("bdi %s[%llu]: ino=%lu memcg_id=%u cgroup_ino=%u page_cgroup_ino=%u", + __entry->name, + __entry->bdi_id, + __entry->ino, + __entry->memcg_id, + __entry->cgroup_ino, + __entry->page_cgroup_ino + ) +); + +TRACE_EVENT(flush_foreign, + + TP_PROTO(struct bdi_writeback *wb, unsigned int frn_bdi_id, + unsigned int frn_memcg_id), + + TP_ARGS(wb, frn_bdi_id, frn_memcg_id), + + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned int, cgroup_ino) + __field(unsigned int, frn_bdi_id) + __field(unsigned int, frn_memcg_id) + ), + + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); + __entry->frn_bdi_id = frn_bdi_id; + __entry->frn_memcg_id = frn_memcg_id; + ), + + TP_printk("bdi %s: cgroup_ino=%u frn_bdi_id=%u frn_memcg_id=%u", + __entry->name, + __entry->cgroup_ino, + __entry->frn_bdi_id, + __entry->frn_memcg_id + ) +); +#endif + DECLARE_EVENT_CLASS(writeback_write_inode_template, TP_PROTO(struct inode *inode, struct writeback_control *wbc), -- cgit v1.2.3 From 0feacaa21634014148068035b02eade71f853496 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 30 Aug 2019 16:39:54 -0700 Subject: writeback: don't access page->mapping directly in track_foreign_dirty TP page->mapping may encode different values in it and page_mapping() should always be used to access the mapping pointer. track_foreign_dirty tracepoint was incorrectly accessing page->mapping directly. Use page_mapping() instead. Also, add NULL checks while at it. Fixes: 3a8e9ac89e6a ("writeback: add tracepoints for cgroup foreign writebacks") Reported-by: Jan Kara Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe --- include/trace/events/writeback.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/trace/events/writeback.h') diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 3dc9fb9e7c78..3a27335fce2c 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -251,9 +251,12 @@ TRACE_EVENT(track_foreign_dirty, ), TP_fast_assign( + struct address_space *mapping = page_mapping(page); + struct inode *inode = mapping ? mapping->host : NULL; + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); __entry->bdi_id = wb->bdi->id; - __entry->ino = page->mapping->host->i_ino; + __entry->ino = inode ? inode->i_ino : 0; __entry->memcg_id = wb->memcg_css->id; __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); __entry->page_cgroup_ino = page->mem_cgroup->css.cgroup->kn->id.ino; -- cgit v1.2.3