4.16-stable review patch. If anyone has any objections, please let me know.
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From: Kan Liang kan.liang@linux.intel.com
[ Upstream commit f58385f629c87a9e210108b39c1f4950d0363ad2 ]
There is a segmentation fault when running 'perf trace'. For example:
[root@jouet e]# perf trace -e *chdir -o /tmp/bla perf report --ignore-vmlinux -i ../perf.data
The perf_mmap__consume() could unmap the mmap. It needs to check the refcnt in perf_mmap__read_done().
Reported-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Kan Liang kan.liang@linux.intel.com Cc: Jiri Olsa jolsa@kernel.org Cc: Namhyung Kim namhyung@kernel.org Cc: Wang Nan wangnan0@huawei.com Fixes: ee023de05f35 ("perf mmap: Introduce perf_mmap__read_done()") Link: http://lkml.kernel.org/r/1522071729-16776-1-git-send-email-kan.liang@linux.i... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/perf/util/mmap.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/tools/perf/util/mmap.c +++ b/tools/perf/util/mmap.c @@ -344,5 +344,11 @@ out: */ void perf_mmap__read_done(struct perf_mmap *map) { + /* + * Check if event was unmapped due to a POLLHUP/POLLERR. + */ + if (!refcount_read(&map->refcnt)) + return; + map->prev = perf_mmap__read_head(map); }