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    SubjectRe: [PATCH v3 4/5][RESEND] page_alloc: Make movablecore_map has higher priority
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    On Tue, 2012-12-11 at 12:56 +0800, Tang Chen wrote:
    > If kernelcore or movablecore is specified at the same time
    > with movablecore_map, movablecore_map will have higher
    > priority to be satisfied.
    > This patch will make find_zone_movable_pfns_for_nodes()
    > calculate zone_movable_pfn[] with the limit from
    > zone_movable_limit[].
    >
    > change log:
    > Move find_usable_zone_for_movable() to free_area_init_nodes()
    > so that sanitize_zone_movable_limit() in patch 3 could use
    > initialized movable_zone.
    >
    > Reported-by: Wu Jianguo <wujianguo@huawei.com>
    >
    > Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
    > Reviewed-by: Wen Congyang <wency@cn.fujitsu.com>
    > Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
    > Tested-by: Lin Feng <linfeng@cn.fujitsu.com>
    > ---
    > mm/page_alloc.c | 28 +++++++++++++++++++++++++---
    > 1 files changed, 25 insertions(+), 3 deletions(-)
    >
    > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    > index 52c368e..00fa67d 100644
    > --- a/mm/page_alloc.c
    > +++ b/mm/page_alloc.c
    > @@ -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));
    > 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]) {
    > + end_pfn = min(end_pfn, zone_movable_limit[nid]);
    > + /* No range left for kernelcore in this node */
    > + if (start_pfn >= end_pfn) {
    > + zone_movable_pfn[nid] =
    > + zone_movable_limit[nid];
    > + break;
    > + }
    > + }
    > +

    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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