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

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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: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2008-04-30 00:53:05 -07:00 committed by Linus Torvalds
parent 7a5e873f09
commit 80fe728d59
1 changed files with 4 additions and 1 deletions
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5
kernel/signal.c
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@ -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);