linux-kernel - Re: [PATCH 1/4] INIT_TASK() should initialize ->thread

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Message-ID: <20100512021537.GA11805@us.ibm.com>
Date:	Tue, 11 May 2010 19:15:37 -0700
From:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Cedric Le Goater <clg@...t.ibm.com>,
	Dave Hansen <haveblue@...ibm.com>,
	Eric Biederman <ebiederm@...ssion.com>,
	Herbert Poetzl <herbert@...hfloor.at>,
	Ingo Molnar <mingo@...e.hu>,
	Mathias Krause <Mathias.Krause@...unet.com>,
	Roland McGrath <roland@...hat.com>,
	Serge Hallyn <serue@...ibm.com>,
	Sukadev Bhattiprolu <sukadev@...ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] INIT_TASK() should initialize ->thread_group list

Oleg Nesterov [oleg@...hat.com] wrote:
| The trivial /sbin/init doing
| 
| 	int main(void)
| 	{
| 		kill(0, SIGKILL)
| 	}
| 
| crashes the kernel.

Really subtle. Good catch.

So, now init is not part of any process group until it calls setsid().
So the above SIGKILL is lost right ? - i.e it does not kill even init
itself.

In my quick test, the following init process lives on inspite of the
SIGKILL.

	main()
	{
		kill(0, SIGKILL);

		while(1)
			sleep(1); 
	}

I don't have a better solution. Maybe a hung init is better than a
crashed kernel. the patches look good.

Acked-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
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