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SubjectRe: [PATCH v12 01/11] mm: deferred_init_memmap improvements
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> This really begs to have two patches... I will not insist though. I also
> suspect the code can be further simplified but again this is nothing to
> block this to go.

Perhaps "page" can be avoided in deferred_init_range(), as pfn is
converted to page in deferred_free_range, but I have not studied it.

>
>> Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
>> Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
>> Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
>> Reviewed-by: Bob Picco <bob.picco@oracle.com>
>
> I do not see any obvious issues in the patch
>
> Acked-by: Michal Hocko <mhocko@suse.com>

Thank you very much!

Pavel

>
>> ---
>> mm/page_alloc.c | 168 ++++++++++++++++++++++++++++----------------------------
>> 1 file changed, 85 insertions(+), 83 deletions(-)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 77e4d3c5c57b..cdbd14829fd3 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -1410,14 +1410,17 @@ void clear_zone_contiguous(struct zone *zone)
>> }
>>
>> #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
>> -static void __init deferred_free_range(struct page *page,
>> - unsigned long pfn, int nr_pages)
>> +static void __init deferred_free_range(unsigned long pfn,
>> + unsigned long nr_pages)
>> {
>> - int i;
>> + struct page *page;
>> + unsigned long i;
>>
>> - if (!page)
>> + if (!nr_pages)
>> return;
>>
>> + page = pfn_to_page(pfn);
>> +
>> /* Free a large naturally-aligned chunk if possible */
>> if (nr_pages == pageblock_nr_pages &&
>> (pfn & (pageblock_nr_pages - 1)) == 0) {
>> @@ -1443,19 +1446,89 @@ static inline void __init pgdat_init_report_one_done(void)
>> complete(&pgdat_init_all_done_comp);
>> }
>>
>> +/*
>> + * Helper for deferred_init_range, free the given range, reset the counters, and
>> + * return number of pages freed.
>> + */
>> +static inline unsigned long __def_free(unsigned long *nr_free,
>> + unsigned long *free_base_pfn,
>> + struct page **page)
>> +{
>> + unsigned long nr = *nr_free;
>> +
>> + deferred_free_range(*free_base_pfn, nr);
>> + *free_base_pfn = 0;
>> + *nr_free = 0;
>> + *page = NULL;
>> +
>> + return nr;
>> +}
>> +
>> +static unsigned long deferred_init_range(int nid, int zid, unsigned long pfn,
>> + unsigned long end_pfn)
>> +{
>> + struct mminit_pfnnid_cache nid_init_state = { };
>> + unsigned long nr_pgmask = pageblock_nr_pages - 1;
>> + unsigned long free_base_pfn = 0;
>> + unsigned long nr_pages = 0;
>> + unsigned long nr_free = 0;
>> + struct page *page = NULL;
>> +
>> + for (; pfn < end_pfn; pfn++) {
>> + /*
>> + * First we check if pfn is valid on architectures where it is
>> + * possible to have holes within pageblock_nr_pages. On systems
>> + * where it is not possible, this function is optimized out.
>> + *
>> + * Then, we check if a current large page is valid by only
>> + * checking the validity of the head pfn.
>> + *
>> + * meminit_pfn_in_nid is checked on systems where pfns can
>> + * interleave within a node: a pfn is between start and end
>> + * of a node, but does not belong to this memory node.
>> + *
>> + * Finally, we minimize pfn page lookups and scheduler checks by
>> + * performing it only once every pageblock_nr_pages.
>> + */
>> + if (!pfn_valid_within(pfn)) {
>> + nr_pages += __def_free(&nr_free, &free_base_pfn, &page);
>> + } else if (!(pfn & nr_pgmask) && !pfn_valid(pfn)) {
>> + nr_pages += __def_free(&nr_free, &free_base_pfn, &page);
>> + } else if (!meminit_pfn_in_nid(pfn, nid, &nid_init_state)) {
>> + nr_pages += __def_free(&nr_free, &free_base_pfn, &page);
>> + } else if (page && (pfn & nr_pgmask)) {
>> + page++;
>> + __init_single_page(page, pfn, zid, nid);
>> + nr_free++;
>> + } else {
>> + nr_pages += __def_free(&nr_free, &free_base_pfn, &page);
>> + page = pfn_to_page(pfn);
>> + __init_single_page(page, pfn, zid, nid);
>> + free_base_pfn = pfn;
>> + nr_free = 1;
>> + cond_resched();
>> + }
>> + }
>> + /* Free the last block of pages to allocator */
>> + nr_pages += __def_free(&nr_free, &free_base_pfn, &page);
>> +
>> + return nr_pages;
>> +}
>> +
>> /* Initialise remaining memory on a node */
>> static int __init deferred_init_memmap(void *data)
>> {
>> pg_data_t *pgdat = data;
>> int nid = pgdat->node_id;
>> - struct mminit_pfnnid_cache nid_init_state = { };
>> unsigned long start = jiffies;
>> unsigned long nr_pages = 0;
>> - unsigned long walk_start, walk_end;
>> - int i, zid;
>> + unsigned long spfn, epfn;
>> + phys_addr_t spa, epa;
>> + int zid;
>> struct zone *zone;
>> unsigned long first_init_pfn = pgdat->first_deferred_pfn;
>> const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
>> + u64 i;
>>
>> if (first_init_pfn == ULONG_MAX) {
>> pgdat_init_report_one_done();
>> @@ -1477,83 +1550,12 @@ static int __init deferred_init_memmap(void *data)
>> if (first_init_pfn < zone_end_pfn(zone))
>> break;
>> }
>> + first_init_pfn = max(zone->zone_start_pfn, first_init_pfn);
>>
>> - for_each_mem_pfn_range(i, nid, &walk_start, &walk_end, NULL) {
>> - unsigned long pfn, end_pfn;
>> - struct page *page = NULL;
>> - struct page *free_base_page = NULL;
>> - unsigned long free_base_pfn = 0;
>> - int nr_to_free = 0;
>> -
>> - end_pfn = min(walk_end, zone_end_pfn(zone));
>> - pfn = first_init_pfn;
>> - if (pfn < walk_start)
>> - pfn = walk_start;
>> - if (pfn < zone->zone_start_pfn)
>> - pfn = zone->zone_start_pfn;
>> -
>> - for (; pfn < end_pfn; pfn++) {
>> - if (!pfn_valid_within(pfn))
>> - goto free_range;
>> -
>> - /*
>> - * Ensure pfn_valid is checked every
>> - * pageblock_nr_pages for memory holes
>> - */
>> - if ((pfn & (pageblock_nr_pages - 1)) == 0) {
>> - if (!pfn_valid(pfn)) {
>> - page = NULL;
>> - goto free_range;
>> - }
>> - }
>> -
>> - if (!meminit_pfn_in_nid(pfn, nid, &nid_init_state)) {
>> - page = NULL;
>> - goto free_range;
>> - }
>> -
>> - /* Minimise pfn page lookups and scheduler checks */
>> - if (page && (pfn & (pageblock_nr_pages - 1)) != 0) {
>> - page++;
>> - } else {
>> - nr_pages += nr_to_free;
>> - deferred_free_range(free_base_page,
>> - free_base_pfn, nr_to_free);
>> - free_base_page = NULL;
>> - free_base_pfn = nr_to_free = 0;
>> -
>> - page = pfn_to_page(pfn);
>> - cond_resched();
>> - }
>> -
>> - if (page->flags) {
>> - VM_BUG_ON(page_zone(page) != zone);
>> - goto free_range;
>> - }
>> -
>> - __init_single_page(page, pfn, zid, nid);
>> - if (!free_base_page) {
>> - free_base_page = page;
>> - free_base_pfn = pfn;
>> - nr_to_free = 0;
>> - }
>> - nr_to_free++;
>> -
>> - /* Where possible, batch up pages for a single free */
>> - continue;
>> -free_range:
>> - /* Free the current block of pages to allocator */
>> - nr_pages += nr_to_free;
>> - deferred_free_range(free_base_page, free_base_pfn,
>> - nr_to_free);
>> - free_base_page = NULL;
>> - free_base_pfn = nr_to_free = 0;
>> - }
>> - /* Free the last block of pages to allocator */
>> - nr_pages += nr_to_free;
>> - deferred_free_range(free_base_page, free_base_pfn, nr_to_free);
>> -
>> - first_init_pfn = max(end_pfn, first_init_pfn);
>> + for_each_free_mem_range(i, nid, MEMBLOCK_NONE, &spa, &epa, NULL) {
>> + spfn = max_t(unsigned long, first_init_pfn, PFN_UP(spa));
>> + epfn = min_t(unsigned long, zone_end_pfn(zone), PFN_DOWN(epa));
>> + nr_pages += deferred_init_range(nid, zid, spfn, epfn);
>> }
>>
>> /* Sanity check that the next zone really is unpopulated */
>> --
>> 2.14.2
>

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