diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c
index 2779c57ad4baf8613a02e9a983f2c5fb7b7be892..995111dee7fba4ffe808ad0f99641d8d2235fb3d 100644
--- a/Documentation/perf_counter/kerneltop.c
+++ b/Documentation/perf_counter/kerneltop.c
@@ -184,6 +184,8 @@ static int			nmi				=  1;
 static int			group				=  0;
 static unsigned int		page_size;
 static unsigned int		mmap_pages			=  16;
+static int			use_mmap			= 0;
+static int			use_munmap			= 0;
 
 static char			*vmlinux;
 
@@ -333,6 +335,8 @@ static void display_help(void)
 	" -z        --zero             # zero counts after display\n"
 	" -D        --dump_symtab      # dump symbol table to stderr on startup\n"
 	" -m pages  --mmap_pages=<pages> # number of mmap data pages\n"
+	" -M        --mmap_info        # print mmap info stream\n"
+	" -U        --munmap_info      # print munmap info stream\n"
 	);
 
 	exit(0);
@@ -1052,9 +1056,11 @@ static void process_options(int argc, char *argv[])
 			{"stat",	no_argument,		NULL, 'S'},
 			{"zero",	no_argument,		NULL, 'z'},
 			{"mmap_pages",	required_argument,	NULL, 'm'},
+			{"mmap_info",	no_argument,		NULL, 'M'},
+			{"munmap_info",	no_argument,		NULL, 'U'},
 			{NULL,		0,			NULL,  0 }
 		};
-		int c = getopt_long(argc, argv, "+:ac:C:d:De:f:g:hn:m:p:s:Sx:z",
+		int c = getopt_long(argc, argv, "+:ac:C:d:De:f:g:hn:m:p:s:Sx:zMU",
 				    long_options, &option_index);
 		if (c == -1)
 			break;
@@ -1092,6 +1098,8 @@ static void process_options(int argc, char *argv[])
 		case 'x': vmlinux			= strdup(optarg); break;
 		case 'z': zero				=              1; break;
 		case 'm': mmap_pages			=   atoi(optarg); break;
+		case 'M': use_mmap			=              1; break;
+		case 'U': use_munmap			=              1; break;
 		default: error = 1; break;
 		}
 	}
@@ -1172,12 +1180,29 @@ static void mmap_read(struct mmap_data *md)
 	last_read = this_read;
 
 	for (; old != head;) {
-		struct event_struct {
+		struct ip_event {
 			struct perf_event_header header;
 			__u64 ip;
 			__u32 pid, tid;
-		} *event = (struct event_struct *)&data[old & md->mask];
-		struct event_struct event_copy;
+		};
+		struct mmap_event {
+			struct perf_event_header header;
+			__u32 pid, tid;
+			__u64 start;
+			__u64 len;
+			__u64 pgoff;
+			char filename[PATH_MAX];
+		};
+
+		typedef union event_union {
+			struct perf_event_header header;
+			struct ip_event ip;
+			struct mmap_event mmap;
+		} event_t;
+
+		event_t *event = (event_t *)&data[old & md->mask];
+
+		event_t event_copy;
 
 		unsigned int size = event->header.size;
 
@@ -1187,7 +1212,7 @@ static void mmap_read(struct mmap_data *md)
 		 */
 		if ((old & md->mask) + size != ((old + size) & md->mask)) {
 			unsigned int offset = old;
-			unsigned int len = sizeof(*event), cpy;
+			unsigned int len = min(sizeof(*event), size), cpy;
 			void *dst = &event_copy;
 
 			do {
@@ -1206,7 +1231,18 @@ static void mmap_read(struct mmap_data *md)
 		switch (event->header.type) {
 		case PERF_EVENT_IP:
 		case PERF_EVENT_IP | __PERF_EVENT_TID:
-			process_event(event->ip, md->counter);
+			process_event(event->ip.ip, md->counter);
+			break;
+
+		case PERF_EVENT_MMAP:
+		case PERF_EVENT_MUNMAP:
+			printf("%s: %Lu %Lu %Lu %s\n",
+					event->header.type == PERF_EVENT_MMAP
+					  ? "mmap" : "munmap",
+					event->mmap.start,
+					event->mmap.len,
+					event->mmap.pgoff,
+					event->mmap.filename);
 			break;
 		}
 	}
@@ -1255,6 +1291,8 @@ int main(int argc, char *argv[])
 			hw_event.record_type	= PERF_RECORD_IRQ;
 			hw_event.nmi		= nmi;
 			hw_event.include_tid	= 1;
+			hw_event.mmap		= use_mmap;
+			hw_event.munmap		= use_munmap;
 
 			fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0);
 			if (fd[i][counter] < 0) {