[mm-unstable v7 11/18] mm/madvise: add huge_memory:mm_madvise_collapse tracepoint

["Zach O'Keefe" <zokeefe@google.com>]

Add a tracepoint to expose mm, address, and enum scan_result of each
hugepage attempted to be collapsed by call to madvise(MADV_COLLAPSE).

Signed-off-by: Zach O'Keefe <zokeefe@google.com>
---
 include/trace/events/huge_memory.h | 22 ++++++++++++++++++++++
 mm/khugepaged.c                    |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index 55392bf30a03..38d339ffdb16 100644
--- a/include/trace/events/huge_memory.h
+++ b/include/trace/events/huge_memory.h
@@ -167,5 +167,27 @@ TRACE_EVENT(mm_collapse_huge_page_swapin,
 		__entry->ret)
 );
 
+TRACE_EVENT(mm_madvise_collapse,
+
+	TP_PROTO(struct mm_struct *mm, unsigned long addr, int result),
+
+	TP_ARGS(mm, addr, result),
+
+	TP_STRUCT__entry(__field(struct mm_struct *, mm)
+			 __field(unsigned long, addr)
+			 __field(int, result)
+	),
+
+	TP_fast_assign(__entry->mm = mm;
+		       __entry->addr = addr;
+		       __entry->result = result;
+	),
+
+	TP_printk("mm=%p addr=%#lx result=%s",
+		  __entry->mm,
+		  __entry->addr,
+		  __print_symbolic(__entry->result, SCAN_STATUS))
+);
+
 #endif /* __HUGE_MEMORY_H */
 #include <trace/define_trace.h>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index e0d00180512c..0207fc0a5b2a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2438,6 +2438,8 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
 		if (!mmap_locked)
 			*prev = NULL;  /* Tell caller we dropped mmap_lock */
 
+		trace_mm_madvise_collapse(mm, addr, result);
+
 		switch (result) {
 		case SCAN_SUCCEED:
 		case SCAN_PMD_MAPPED:
-- 
2.37.0.rc0.161.g10f37bed90-goog