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SubjectRe: [PATCH v3 4/5][RESEND] page_alloc: Make movablecore_map has higher priority
Hi Simon,

Thanks for reviewing. This logic is aimed at make movablecore_map
coexist with kernelcore/movablecore.

Please see below. :)

On 12/12/2012 09:33 AM, Simon Jeons wrote:
>> @@ -4839,9 +4839,17 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>> required_kernelcore = max(required_kernelcore, corepages);
>> }
>>
>> - /* If kernelcore was not specified, there is no ZONE_MOVABLE */
>> - if (!required_kernelcore)
>> + /*
>> + * If neither kernelcore/movablecore nor movablecore_map is specified,
>> + * there is no ZONE_MOVABLE. But if movablecore_map is specified, the
>> + * start pfn of ZONE_MOVABLE has been stored in zone_movable_limit[].
>> + */
>> + if (!required_kernelcore) {
>> + if (movablecore_map.nr_map)
>> + memcpy(zone_movable_pfn, zone_movable_limit,
>> + sizeof(zone_movable_pfn));

If users didn't specified kernelcore option, then zone_movable_pfn[]
and zone_movable_limit[] are all the same. We skip the logic.

>> goto out;
>> + }
>>
>> /* usable_startpfn is the lowest possible pfn ZONE_MOVABLE can be at */
>> usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
>> @@ -4871,10 +4879,24 @@ restart:
>> for_each_mem_pfn_range(i, nid,&start_pfn,&end_pfn, NULL) {
>> unsigned long size_pages;
>>
>> + /*
>> + * Find more memory for kernelcore in
>> + * [zone_movable_pfn[nid], zone_movable_limit[nid]).
>> + */
>> start_pfn = max(start_pfn, zone_movable_pfn[nid]);
>> if (start_pfn>= end_pfn)
>> continue;
>>
>
> Hi Chen,
>
>> + if (zone_movable_limit[nid]) {

If users didn't give any limitation of ZONE_MOVABLE on node i, we could
skip the logic too.

>> + end_pfn = min(end_pfn, zone_movable_limit[nid]);

In order to reuse the original kernelcore/movablecore logic, we keep
end_pfn <= zone_movable_limit[nid]. We device [start_pfn, end_pfn) into
two parts:
[start_pfn, zone_movable_limit[nid])
and
[zone_movable_limit[nid], end_pfn).

We just remove the second part, and go on to the original logic.

>> + /* No range left for kernelcore in this node */
>> + if (start_pfn>= end_pfn) {

Since we re-evaluated end_pfn, if we have crossed the limitation, we
should stop.

>> + zone_movable_pfn[nid] =
>> + zone_movable_limit[nid];

Here, we found the real limitation. That means, the lowest pfn of
ZONE_MOVABLE is either zone_movable_limit[nid] or the value the original
logic calculates out, which is below zone_movable_limit[nid].

>> + break;

Then we break and go on to the next node.

>> + }
>> + }
>> +
>
> Could you explain this part of codes? hard to understand.
>
>> /* Account for what is only usable for kernelcore */
>> if (start_pfn< usable_startpfn) {
>> unsigned long kernel_pages;
>> @@ -4934,12 +4956,12 @@ restart:
>> if (usable_nodes&& required_kernelcore> usable_nodes)
>> goto restart;
>>
>> +out:
>> /* Align start of ZONE_MOVABLE on all nids to MAX_ORDER_NR_PAGES */
>> for (nid = 0; nid< MAX_NUMNODES; nid++)
>> zone_movable_pfn[nid] =
>> roundup(zone_movable_pfn[nid], MAX_ORDER_NR_PAGES);
>>
>> -out:
>> /* restore the node_state */
>> node_states[N_HIGH_MEMORY] = saved_node_state;
>> }
>
>
>



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