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.
Signed-off-by: Tejun Heo <[email protected]> Reported-by: Jan Kara <[email protected]> Fixes: 3a8e9ac89e6a ("writeback: add tracepoints for cgroup foreign writebacks") --- include/trace/events/writeback.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) 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;
