From 973186ca7fe94d770a9847d7d530864de6ab638b Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Fri, 23 Sep 2016 17:38:34 +0300 Subject: [PATCH] perf tools: Fix MMAP event synthesis broken by MAP_HUGETLB change Patch "perf record: Mark MAP_HUGETLB when synthesizing mmap events") breaks MMAP event synthesis. The executable name comparison will match any name if the length is zero, resulting in all the user space maps becoming anonymous. This is particularly noticeable with system-wide traces. Example: perf record -a sleep 1 perf script --show-mmap-events Committer note: That is not the case when, say, one has a qemu instance and libvirt actually mounts hugetlbfs. To test this I had to first umount it: [root@jouet ~]# mount | grep hugetlbfs hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel) [root@jouet ~]# After unmount it the error fixed by this patch manifests itself: # perf record -a sleep 1 # perf script --show-mmap-events | grep PERF_RECORD_MMAP2 | head -5 systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x557d47ed8000(0x167000) @ 0 fd:00 3146896 7362875424355726126]: r-xp //anon systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c488d000(0x4000) @ 0 fd:00 3153214 7362875424355726126]: r-xp //anon systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4a92000(0x3d000) @ 0 fd:00 3159276 7362875424355726126]: r-xp //anon systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4cd5000(0x15000) @ 0 fd:00 3153725 7362875424355726126]: r-xp //anon systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4eeb000(0x25000) @ 0 fd:00 3153260 7362875424355726126]: r-xp //anon # Fixed version: # perf record -a sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.419 MB perf.data (182 samples) ] # perf script --show-mmap-events | grep PERF_RECORD_MMAP2 | head -5 systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x557d47ed8000(0x167000) @ 0 fd:00 3146896 7362875424355726126]: r-xp /usr/lib/systemd/systemd systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c488d000(0x4000) @ 0 fd:00 3153214 7362875424355726126]: r-xp /usr/lib64/libuuid.so.1.3.0 systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4a92000(0x3d000) @ 0 fd:00 3159276 7362875424355726126]: r-xp /usr/lib64/libblkid.so.1.1.0 systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4cd5000(0x15000) @ 0 fd:00 3153725 7362875424355726126]: r-xp /usr/lib64/libz.so.1.2.8 systemd 0 [000] 0.000000: PERF_RECORD_MMAP2 1/1: [0x7f96c4eeb000(0x25000) @ 0 fd:00 3153260 7362875424355726126]: r-xp /usr/lib64/liblzma.so.5.2.2 [root@jouet ~]# Signed-off-by: Adrian Hunter Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Mathieu Poirier Link: http://lkml.kernel.org/r/1474641528-18776-3-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/event.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c index 2880e2226fdb..8ab0d7da956b 100644 --- a/tools/perf/util/event.c +++ b/tools/perf/util/event.c @@ -346,7 +346,8 @@ out: if (!strcmp(execname, "")) strcpy(execname, anonstr); - if (!strncmp(execname, hugetlbfs_mnt, hugetlbfs_mnt_len)) { + if (hugetlbfs_mnt_len && + !strncmp(execname, hugetlbfs_mnt, hugetlbfs_mnt_len)) { strcpy(execname, anonstr); event->mmap2.flags |= MAP_HUGETLB; } -- 2.11.0