Re: perf terminates immediately with segfault in dmesg

[David Ahern <dsahern@gmail.com>]

On 2/27/13 7:21 AM, Dongsoo Nathaniel Kim wrote:
> Hi,
>
> I'm trying to profile kvm guest and host as well.
> I checked out v3.8 vanilla kernel and built bundled perf tool.
> (commit 19f949f52599ba7c3f67a5897ac6be14bfcb1200)
>
> Here is my command line:
> sudo perf kvm --host --guest --guestmount=/tmp/guestmount record -o
> my.perf.data
> (I mounted guest instance on /tmp/guestmount using sshfs)
>
> and perf gets terminated immediately and no clue but segfault message in
> dmesg:
> [11618.130483] perf[39937]: segfault at 30 ip 00007fed26de1121 sp
> 00007fff0394c258 error 4 in libc-2.15.so[7fed26d58000+1b5000]
>
> Any idea? Can too many processor core cause this problem?

Does this solve the problem for you?

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index ca3f80e..e55701d 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -973,7 +973,7 @@ __cmd_buildid_list(const char *file_name, int argc, 
const char **argv)

  int cmd_kvm(int argc, const char **argv, const char *prefix 
__maybe_unused)
  {
-   const char *file_name;
+   const char *file_name = NULL;

     const struct option kvm_options[] = {
         OPT_STRING('i', "input", &file_name, "file",