When the tracer of process is outside of current pid namespace, field `TracerPid` in /proc/<pid>/status will be 0, too, just like this process not have been traced. This is because that function `task_pid_nr_ns` used to get the pid of tracer will return 0 in this situation. Co-authored-by: Yuan Haisheng <heysion@xxxxxxxxxx> Signed-off-by: Chen Linxuan <chenlinxuan@xxxxxxxxxxxxx> --- Documentation/filesystems/proc.rst | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 898c99eae8e4..e98e0277f05e 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -245,7 +245,8 @@ It's slow but very precise. Ngid NUMA group ID (0 if none) Pid process id PPid process id of the parent process - TracerPid PID of process tracing this process (0 if not) + TracerPid PID of process tracing this process (0 if not, or + the tracer is outside of the current pid namespace) Uid Real, effective, saved set, and file system UIDs Gid Real, effective, saved set, and file system GIDs FDSize number of file descriptor slots currently allocated -- 2.38.1
