diff mbox series

[RFC,v2,01/10] mm: page_ref_add_unless() does not trace 'u' argument

Message ID 20211117012059.141450-2-pasha.tatashin@soleen.com (mailing list archive)
State New
Headers show
Series Hardening page _refcount | expand

Commit Message

Pasha Tatashin Nov. 17, 2021, 1:20 a.m. UTC 
In other page_ref_* functions all arguments and returns are traced, but
in page_ref_add_unless the 'u' argument which stands for unless boolean
is not traced. However, what is more confusing is that in the tracing
routine:
	__page_ref_mod_unless(struct page *page, int v, int u);

The 'u' argument present, but instead a return value is passed into
this argument.

Add a new template specific for page_ref_add_unless(), and trace all
arguments and the return value.

Fixes: 95813b8faa0c ("mm/page_ref: add tracepoint to track down page reference manipulation")

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
---
 include/linux/page_ref.h        | 10 ++++----
 include/trace/events/page_ref.h | 43 ++++++++++++++++++++++++++++++---
 mm/debug_page_ref.c             |  8 +++---
 3 files changed, 49 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/page_ref.h b/include/linux/page_ref.h
index 2e677e6ad09f..1903af5fb087 100644
--- a/include/linux/page_ref.h
+++ b/include/linux/page_ref.h
@@ -11,7 +11,7 @@  DECLARE_TRACEPOINT(page_ref_set);
 DECLARE_TRACEPOINT(page_ref_mod);
 DECLARE_TRACEPOINT(page_ref_mod_and_test);
 DECLARE_TRACEPOINT(page_ref_mod_and_return);
-DECLARE_TRACEPOINT(page_ref_mod_unless);
+DECLARE_TRACEPOINT(page_ref_add_unless);
 DECLARE_TRACEPOINT(page_ref_freeze);
 DECLARE_TRACEPOINT(page_ref_unfreeze);
 
@@ -30,7 +30,7 @@  extern void __page_ref_set(struct page *page, int v);
 extern void __page_ref_mod(struct page *page, int v);
 extern void __page_ref_mod_and_test(struct page *page, int v, int ret);
 extern void __page_ref_mod_and_return(struct page *page, int v, int ret);
-extern void __page_ref_mod_unless(struct page *page, int v, int u);
+extern void __page_ref_add_unless(struct page *page, int v, int u, int ret);
 extern void __page_ref_freeze(struct page *page, int v, int ret);
 extern void __page_ref_unfreeze(struct page *page, int v);
 
@@ -50,7 +50,7 @@  static inline void __page_ref_mod_and_test(struct page *page, int v, int ret)
 static inline void __page_ref_mod_and_return(struct page *page, int v, int ret)
 {
 }
-static inline void __page_ref_mod_unless(struct page *page, int v, int u)
+static inline void __page_ref_add_unless(struct page *page, int v, int u, int ret)
 {
 }
 static inline void __page_ref_freeze(struct page *page, int v, int ret)
@@ -237,8 +237,8 @@  static inline bool page_ref_add_unless(struct page *page, int nr, int u)
 {
 	bool ret = atomic_add_unless(&page->_refcount, nr, u);
 
-	if (page_ref_tracepoint_active(page_ref_mod_unless))
-		__page_ref_mod_unless(page, nr, ret);
+	if (page_ref_tracepoint_active(page_ref_add_unless))
+		__page_ref_add_unless(page, nr, u, ret);
 	return ret;
 }
 
diff --git a/include/trace/events/page_ref.h b/include/trace/events/page_ref.h
index 8a99c1cd417b..c32d6d161cdb 100644
--- a/include/trace/events/page_ref.h
+++ b/include/trace/events/page_ref.h
@@ -94,6 +94,43 @@  DECLARE_EVENT_CLASS(page_ref_mod_and_test_template,
 		__entry->val, __entry->ret)
 );
 
+DECLARE_EVENT_CLASS(page_ref_add_unless_template,
+
+	TP_PROTO(struct page *page, int v, int u, int ret),
+
+	TP_ARGS(page, v, u, ret),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, pfn)
+		__field(unsigned long, flags)
+		__field(int, count)
+		__field(int, mapcount)
+		__field(void *, mapping)
+		__field(int, mt)
+		__field(int, val)
+		__field(int, unless)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		__entry->pfn = page_to_pfn(page);
+		__entry->flags = page->flags;
+		__entry->count = page_ref_count(page);
+		__entry->mapcount = page_mapcount(page);
+		__entry->mapping = page->mapping;
+		__entry->mt = get_pageblock_migratetype(page);
+		__entry->val = v;
+		__entry->ret = ret;
+	),
+
+	TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d unless=%d ret=%d",
+		__entry->pfn,
+		show_page_flags(__entry->flags & PAGEFLAGS_MASK),
+		__entry->count,
+		__entry->mapcount, __entry->mapping, __entry->mt,
+		__entry->val, __entry->unless, __entry->ret)
+);
+
 DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_and_test,
 
 	TP_PROTO(struct page *page, int v, int ret),
@@ -108,11 +145,11 @@  DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_and_return,
 	TP_ARGS(page, v, ret)
 );
 
-DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_mod_unless,
+DEFINE_EVENT(page_ref_add_unless_template, page_ref_add_unless,
 
-	TP_PROTO(struct page *page, int v, int ret),
+	TP_PROTO(struct page *page, int v, int u, int ret),
 
-	TP_ARGS(page, v, ret)
+	TP_ARGS(page, v, u, ret)
 );
 
 DEFINE_EVENT(page_ref_mod_and_test_template, page_ref_freeze,
diff --git a/mm/debug_page_ref.c b/mm/debug_page_ref.c
index f3b2c9d3ece2..1426d6887b01 100644
--- a/mm/debug_page_ref.c
+++ b/mm/debug_page_ref.c
@@ -33,12 +33,12 @@  void __page_ref_mod_and_return(struct page *page, int v, int ret)
 EXPORT_SYMBOL(__page_ref_mod_and_return);
 EXPORT_TRACEPOINT_SYMBOL(page_ref_mod_and_return);
 
-void __page_ref_mod_unless(struct page *page, int v, int u)
+void __page_ref_add_unless(struct page *page, int v, int u, int ret)
 {
-	trace_page_ref_mod_unless(page, v, u);
+	trace_page_ref_add_unless(page, v, u, ret);
 }
-EXPORT_SYMBOL(__page_ref_mod_unless);
-EXPORT_TRACEPOINT_SYMBOL(page_ref_mod_unless);
+EXPORT_SYMBOL(__page_ref_add_unless);
+EXPORT_TRACEPOINT_SYMBOL(page_ref_add_unless);
 
 void __page_ref_freeze(struct page *page, int v, int ret)
 {