[PATCH] Add a slab corruption tracepoint

[David Howells <dhowells@redhat.com>]

    
Add a tracepoint to log slab corruption messages to the trace log also so
that it's easier to correlate with other trace messages that are being used
to track refcounting.

Signed-off-by: David Howells <dhowells@redhat.com>
---
 include/trace/events/kmem.h |   23 +++++++++++++++++++++++
 mm/slab.c                   |    2 ++
 2 files changed, 25 insertions(+)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index eb57e3037deb..c96f3b03a6e2 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -315,6 +315,29 @@ TRACE_EVENT(mm_page_alloc_extfrag,
 		__entry->change_ownership)
 );
 
+TRACE_EVENT(slab_corruption,
+	TP_PROTO(const char *slab, void *object, unsigned int size, unsigned int offset),
+
+	TP_ARGS(slab, object, size, offset),
+
+	TP_STRUCT__entry(
+		__field(	void *,		object		)
+		__field(	unsigned int,	size		)
+		__field(	unsigned int,	offset		)
+		__array(	char,		slab, 16	)
+	),
+
+	TP_fast_assign(
+		strlcpy(__entry->slab, slab, sizeof(__entry->slab));
+		__entry->object		= object;
+		__entry->size		= size;
+		__entry->offset		= offset;
+	),
+
+	TP_printk("slab=%s obj=%px size=%x off=%x",
+		  __entry->slab, __entry->object, __entry->size, __entry->offset)
+);
+
 #endif /* _TRACE_KMEM_H */
 
 /* This part must be outside protection */
diff --git a/mm/slab.c b/mm/slab.c
index 9df370558e5d..47c5a86e39be 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1527,6 +1527,8 @@ static void check_poison_obj(struct kmem_cache *cachep, void *objp)
 				       print_tainted(), cachep->name,
 				       realobj, size);
 				print_objinfo(cachep, objp, 0);
+				trace_slab_corruption(cachep->name, realobj,
+						      size, i);
 			}
 			/* Hexdump the affected line */
 			i = (i / 16) * 16;