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Subject[PATCH 1/3] ptrace: give more respect to SIGKILL
ptrace_stop() has some complicated checks to prevent the scheduling in the
TASK_TRACED state with the pending SIGKILL, but these checks are racy, and
they depend on arch_ptrace_stop_needed().

This patch assumes that the traced task should die asap if it was killed by
SIGKILL, in that case schedule()->signal_pending_state() has no reason to
ignore the TASK_WAKEKILL part of TASK_TRACED, and we can kill this nasty
special case.

Note: do_exit()->ptrace_notify() is special, the killed task can already
dequeue SIGKILL at this point. Another indication that fatal_signal_pending()
is not exactly right.

Signed-off-by: Oleg Nesterov <>

--- 26-rc2/include/linux/sched.h~1_KILL_TRACED_CHECK 2008-06-01 16:44:39.000000000 +0400
+++ 26-rc2/include/linux/sched.h 2008-06-01 16:44:39.000000000 +0400
@@ -2034,9 +2034,6 @@ static inline int signal_pending_state(l
if (!signal_pending(p))
return 0;

- if (state & (__TASK_STOPPED | __TASK_TRACED))
- return 0;
return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);

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