syscall_regfunc() ignores the kernel threads because "it has no effect",
see cc3b13c1 "Don't trace kernel thread syscalls" which added this check.
However, this means that a user-space task spawned by call_usermodehelper()
will run without TIF_SYSCALL_TRACEPOINT if sys_tracepoint_refcount != 0.
Remove this check. The unnecessary report from ret_from_fork path mentioned
by cc3b13c1 is no longer possible, see See commit fb45550d76bb5 "make sure
that kernel_thread() callbacks call do_exit() themselves".
A kernel_thread() callback can only return and take the int_ret_from_sys_call
path after do_execve() succeeds, otherwise the kernel will crash. But in this
case it is no longer a kernel thread and thus is needs TIF_SYSCALL_TRACEPOINT.
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
kernel/tracepoint.c | 4 +---
1 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index d907b7b..08456ba 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -747,9 +747,7 @@ void syscall_regfunc(void)
if (!sys_tracepoint_refcount) {
read_lock(&tasklist_lock);
for_each_process_thread(p, t) {
- /* Skip kernel threads. */
- if (!(t->flags & PF_KTHREAD))
- set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
+ set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
}
read_unlock(&tasklist_lock);
}
--
1.5.5.1
--
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