Re: /proc/sys/kernel/pid_max issues

[William Lee Irwin III]

On Sun, Sep 12, 2004 at 02:36:05AM -0700, William Lee Irwin III wrote:
>> +		if (map > &pidmap_array[pid_max/BITS_PER_PAGE])
>> +			map = pidmap_array;
>>  		if (unlikely(!map->page)) {
>>  			unsigned long page = get_zeroed_page(GFP_KERNEL);

On Sun, Sep 12, 2004 at 02:58:05AM -0700, William Lee Irwin III wrote:
> If pid_max == BITS_PER_PAGE*n, none of &pidmap_array[pid_max/BITS_PER_PAGE]
> is usable, so if we must complete a full revolution around pidmap_array[]
> to discover a free pid slightly less than last_pid we will miss it. Hence:

That could only happen if max_steps were initialized to PIDMAP_ENTRIES
instead of PIDMAP_ENTRIES + 1, so this more accurate upper bound is not
strictly necessary, though with this in place, we could probably reduce
max_steps to just PIDMAP_ENTRIES so we cycle no further than the block
we began; I'll not bother with that.


-- wli
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