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Date: Thu, 2 Dec 2004 17:04:17 -0800
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From: Roland McGrath <roland@redhat.com>
To: Manfred Spraul <manfred@colorfullife.com>
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Cc: Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@osdl.org>,
       torvalds@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] use pid_alive in proc_pid_status
In-Reply-To: Manfred Spraul's message of  Monday, 29 November 2004 18:58:30 +0100 <41AB6346.2080601@colorfullife.com>
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> But I don't understand the lines in wait_task_zombie that reset 
> exit_state from DEAD to ZOMBIE, so perhaps I overlook something.

This happens when a sys_wait* call tries to reap a process, but then has
some problem like EFAULT.  It then abandons the reaping attempt by turning
DEAD back into ZOMBIE, so another sys_wait* call can succeed later.  So,
during this brief window it can be in DEAD though it in fact is never
reaped and the PID remains bound to that task_struct throughout.
If you don't want to rule out ZOMBIE, you can't really rule out DEAD.


Thanks,
Roland