On 06.04.22 17:18, Zi Yan wrote:
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> Enable set_migratetype_isolate() to check specified sub-range for
> unmovable pages during isolation. Page isolation is done
> at MAX_ORDER_NR_PAEGS granularity, but not all pages within that
> granularity are intended to be isolated. For example,
> alloc_contig_range(), which uses page isolation, allows ranges without
> alignment. This commit makes unmovable page check only look for
> interesting pages, so that page isolation can succeed for any
> non-overlapping ranges.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
> ---
[...]
> /*
> - * This function checks whether pageblock includes unmovable pages or not.
> + * This function checks whether the range [start_pfn, end_pfn) includes
> + * unmovable pages or not. The range must fall into a single pageblock and
> + * consequently belong to a single zone.
> *
> * PageLRU check without isolation or lru_lock could race so that
> * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
> @@ -28,12 +30,14 @@
> * cannot get removed (e.g., via memory unplug) concurrently.
> *
> */
> -static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> - int migratetype, int flags)
> +static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long end_pfn,
> + int migratetype, int flags)
> {
> - unsigned long iter = 0;
> - unsigned long pfn = page_to_pfn(page);
> - unsigned long offset = pfn % pageblock_nr_pages;
> + unsigned long pfn = start_pfn;
> + struct page *page = pfn_to_page(pfn);
Just do
struct page *page = pfn_to_page(start_pfn);
struct zone *zone = page_zone(page);
here. No need to lookup the zone again in the loop because, as you
document "must ... belong to a single zone.".
Then, there is also no need to initialize "pfn" here. In the loop header
is sufficient.
> +
> + VM_BUG_ON(ALIGN_DOWN(start_pfn, pageblock_nr_pages) !=
> + ALIGN_DOWN(end_pfn - 1, pageblock_nr_pages));
>
> if (is_migrate_cma_page(page)) {
> /*
> @@ -47,8 +51,11 @@ static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> return page;
> }
>
> - for (; iter < pageblock_nr_pages - offset; iter++) {
> - page = pfn_to_page(pfn + iter);
> + for (pfn = start_pfn; pfn < end_pfn; pfn++) {
> + struct zone *zone;
> +
> + page = pfn_to_page(pfn);
> + zone = page_zone(page);
>
> /*
> * Both, bootmem allocations and memory holes are marked
> @@ -85,7 +92,7 @@ static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> }
>
> skip_pages = compound_nr(head) - (page - head);
> - iter += skip_pages - 1;
> + pfn += skip_pages - 1;
> continue;
> }
>
> @@ -97,7 +104,7 @@ static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> */
> if (!page_ref_count(page)) {
> if (PageBuddy(page))
> - iter += (1 << buddy_order(page)) - 1;
> + pfn += (1 << buddy_order(page)) - 1;
> continue;
> }
>
> @@ -134,11 +141,18 @@ static struct page *has_unmovable_pages(struct zone *zone, struct page *page,
> return NULL;
> }
>
> -static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
> +/*
> + * This function set pageblock migratetype to isolate if no unmovable page is
> + * present in [start_pfn, end_pfn). The pageblock must intersect with
> + * [start_pfn, end_pfn).
> + */
> +static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags,
> + unsigned long start_pfn, unsigned long end_pfn)
I think we might be able do better, eventually not passing start_pfn at
all. Hmm.
I think we want to pull out the
start_isolate_page_range()/undo_isolate_page_range() interface change
into a separate patch.
Let me try to give it a shot, I'll try hacking something up real quick
to see if we can do better.
--
Thanks,
David / dhildenb
