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Commit 80fe728d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

signals: allow the kernel to actually kill /sbin/init 



Currently the buggy /sbin/init hangs if SIGSEGV/etc happens.  The kernel sends
the signal, init dequeues it and ignores, returns from the exception, repeats
the faulting instruction, and so on forever.

Imho, such a behaviour is not good.  I think that the explicit loud death of
the buggy /sbin/init is better than the silent hang.

Change force_sig_info() to clear SIGNAL_UNKILLABLE when the task should be
really killed.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7a5e873f

kernel/signal.c

+4 −1
Original line number Diff line number Diff line
@@ -892,7 +892,8 @@ specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t) 
 * since we do not want to have a signal handler that was blocked

 * be invoked when user space had explicitly blocked it.

 *

 * We don't want to have recursive SIGSEGV's etc, for example.

 * We don't want to have recursive SIGSEGV's etc, for example,

 * that is why we also clear SIGNAL_UNKILLABLE.

 */

int

force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
@@ -912,6 +913,8 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) 
			recalc_sigpending_and_wake(t);

		}

	}

	if (action->sa.sa_handler == SIG_DFL)

		t->signal->flags &= ~SIGNAL_UNKILLABLE;

	ret = specific_send_sig_info(sig, info, t);

	spin_unlock_irqrestore(&t->sighand->siglock, flags);