Date: Tue, 15 Jun 2010 20:35:25 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>, Salman <sqazi@google.com>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org, peterz@infradead.org,
       tytso@google.com, torvalds@linux-foundation.org, walken@google.com
Subject: [PATCH 0/1] (Was: Fix a race in pid generation that causes pids to
	be reused immediately.)
Message-ID: <20100615183525.GA24577@redhat.com>
References: <AANLkTinlnb-HsDia4X2qgRjkTL_Z5CfVKYHRFwREoyIn@mail.gmail.com> <20100611224902.5039.60134.stgit@bumblebee1.mtv.corp.google.com>
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On 06/11, Salman wrote:
>
> A program that repeatedly forks and waits is susceptible to having the
> same pid repeated,

I agree this patch should fix this.

But the kernel still can use the same pid twice in a row, I am wondering
if there a simple solution to prevent this. Probably not, and this case
is unlikely.

While we are here, and given that many reviewers recently inspected
alloc_pidmap(), probably someone can explain the mysterious checks
in do/while loop ?

See the patch I am going to send, it is on top on Salman's fix but doesn't
really depend on it.

Oleg.

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