David Hildenbrand
2022-Apr-12 13:10 UTC
[PATCH v10 2/5] mm: page_isolation: check specified range for unmovable pages
On 06.04.22 17:18, Zi Yan wrote:> From: Zi Yan <ziy at nvidia.com> > > 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 at nvidia.com> > ---[...]> /* > - * 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