Date: Sun, 12 Sep 2004 02:43:33 -0700
From: William Lee Irwin III <wli@holomorphy.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Anton Blanchard <anton@samba.org>, linux-kernel@vger.kernel.org,
       viro@parcelfarce.linux.theplanet.co.uk
Subject: Re: /proc/sys/kernel/pid_max issues
Message-ID: <20040912094333.GK2660@holomorphy.com>
Mail-Followup-To: William Lee Irwin III <wli@holomorphy.com>,
	Ingo Molnar <mingo@elte.hu>, Anton Blanchard <anton@samba.org>,
	linux-kernel@vger.kernel.org,
	viro@parcelfarce.linux.theplanet.co.uk
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On Sun, Sep 12, 2004 at 11:39:43AM +0200, Ingo Molnar wrote:
> --- linux/kernel/pid.c.orig	
> +++ linux/kernel/pid.c	
> @@ -103,7 +103,7 @@ int alloc_pidmap(void)
>  	pidmap_t *map;
>  
>  	pid = last_pid + 1;
> -	if (pid >= pid_max)
> +	if (unlikely(pid >= pid_max))
>  		pid = RESERVED_PIDS;

Well, this part won't change the wrapping behavior.

On Sun, Sep 12, 2004 at 11:39:43AM +0200, Ingo Molnar wrote:
>  	offset = pid & BITS_PER_PAGE_MASK;
> @@ -116,6 +116,10 @@ int alloc_pidmap(void)
>  		 * slowpath and that fixes things up.
>  		 */
>  return_pid:
> +		if (unlikely(pid >= pid_max)) {
> +			clear_bit(offset, map->page);
> +			goto failure;
> +		}
>  		atomic_dec(&map->nr_free);
>  		last_pid = pid;
>  		return pid;

This is too late; it hands back a hard failure without resetting last_pid.


-- wli
-
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