From: Ralf Baechle <ralf@linux-mips.org>
To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: linux-mips@linux-mips.org
Subject: Re: unkillable process due to setup_frame() failure
Date: Tue, 6 Sep 2005 19:41:19 +0100 [thread overview]
Message-ID: <20050906184118.GC3102@linux-mips.org> (raw)
In-Reply-To: <20050907.014234.108739386.anemo@mba.ocn.ne.jp>
On Wed, Sep 07, 2005 at 01:42:34AM +0900, Atsushi Nemoto wrote:
> 1. The "break" instruction raises a exception.
> 2. The exception handler queues SIGTRAP(5).
> 3. dequeue_signal() dequeue a signal with LOWEST number (i.e. SIGTRAP).
> 4. setup_frame() fails due to bad stack pointer and queues SIGSEGV(11).
> 5. returns to user process (pc unchanged).
> 6. goto 1. (forever)
>
> So, the process can not be kill by SIGKILL. In 2.6.12, 'sigkill
> priority fix' was applied to __dequeue_signal(), but it does not help
> while the SIGTRAP is queued to tsk->pending but SIGKILL (by kill
> command) is queued to tsk->signal->shared_pending.
The behaviour of not advancing the EPC beyond the faulting instruction is
part of the problem - but I believe that was the usual behaviour for
MIPS UNIXoid operating systems.
Ralf
next prev parent reply other threads:[~2005-09-06 18:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-06 16:42 unkillable process due to setup_frame() failure Atsushi Nemoto
2005-09-06 18:41 ` Ralf Baechle [this message]
2005-09-07 9:14 ` Maciej W. Rozycki
2005-09-07 13:47 ` Ralf Baechle
2005-09-07 14:44 ` Atsushi Nemoto
2005-09-07 14:56 ` Atsushi Nemoto
2005-09-07 15:24 ` Maciej W. Rozycki
2005-09-07 16:11 ` Ralf Baechle
2005-09-07 16:34 ` Maciej W. Rozycki
2005-09-15 16:17 ` Atsushi Nemoto
2005-09-15 16:44 ` Ralf Baechle
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