On 12/15/18 12:03 AM, Mel Gorman wrote: > release_pages() is a simpler version of free_unref_page_list() but it > tracks the highest PFN for caching the restart point of the compaction > free scanner. This patch optionally tracks the highest PFN in the core > helper and converts compaction to use it. > > Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]> Nit below: > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2961,18 +2961,26 @@ void free_unref_page(struct page *page) > /* > * Free a list of 0-order pages > */ > -void free_unref_page_list(struct list_head *list) > +void __free_page_list(struct list_head *list, bool dropref, > + unsigned long *highest_pfn) > { > struct page *page, *next; > unsigned long flags, pfn; > int batch_count = 0; > > + if (highest_pfn) > + *highest_pfn = 0; > + > /* Prepare pages for freeing */ > list_for_each_entry_safe(page, next, list, lru) { > + if (dropref) > + WARN_ON_ONCE(!put_page_testzero(page)); That will warn just once, but then page will remain with elevated count and free_unref_page_prepare() will warn either immediately or later depending on DEBUG_VM, for each page. Also IIRC it's legal for basically anyone to do get_page_unless_zero() and later put_page(), and this would now cause warning. Maybe just test for put_page_testzero() result without warning, and continue? Hm but then we should still do a list_del() and that becomes racy after dropping our ref... > pfn = page_to_pfn(page); > if (!free_unref_page_prepare(page, pfn)) > list_del(&page->lru); > set_page_private(page, pfn); > + if (highest_pfn && pfn > *highest_pfn) > + *highest_pfn = pfn; > } > > local_irq_save(flags); >
