Hi, On 2021/11/26 21:42, David Hildenbrand wrote:
In the loop, pfn + i, 1 << order are repeatedly calculated. 1 << order is a step size, pfn + i is each step position.Let's prepare our fake page onlining code for subblock size smaller than MAX_ORDER - 1: we might get called for ranges not covering properly aligned MAX_ORDER - 1 pages. We have to detect the order to use dynamically. Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> --- drivers/virtio/virtio_mem.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 03e1c5743699..50de7582c9f8 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -1121,15 +1121,18 @@ static void virtio_mem_clear_fake_offline(unsigned long pfn, */ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages) { - const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES; + unsigned long order = MAX_ORDER - 1; unsigned long i;/*- * We are always called at least with MAX_ORDER_NR_PAGES - * granularity/alignment (e.g., the way subblocks work). All pages - * inside such a block are alike. + * We might get called for ranges that don't cover properly aligned + * MAX_ORDER - 1 pages; however, we can only online properly aligned + * pages with an order of MAX_ORDER - 1 at maximum. */ - for (i = 0; i < nr_pages; i += max_nr_pages) { + while (!IS_ALIGNED(pfn | nr_pages, 1 << order)) + order--; + + for (i = 0; i < nr_pages; i += 1 << order) { struct page *page = pfn_to_page(pfn + i);/*@@ -1139,14 +1142,12 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages) * alike. */ if (PageDirty(page)) { - virtio_mem_clear_fake_offline(pfn + i, max_nr_pages, - false); - generic_online_page(page, MAX_ORDER - 1); + virtio_mem_clear_fake_offline(pfn + i, 1 << order, false); + generic_online_page(page, order); } else { - virtio_mem_clear_fake_offline(pfn + i, max_nr_pages, - true); - free_contig_range(pfn + i, max_nr_pages); - adjust_managed_page_count(page, max_nr_pages); + virtio_mem_clear_fake_offline(pfn + i, 1 << order, true); + free_contig_range(pfn + i, 1 << order); + adjust_managed_page_count(page, 1 << order);
Better to figure the numer once each iter? LGTL. LGTM. Reviewed-by: Eric Ren <renzhengeek@xxxxxxxxx>
} } } @@ -2477,7 +2478,6 @@ static int virtio_mem_init_hotplug(struct virtio_mem *vm) /* * We want subblocks to span at least MAX_ORDER_NR_PAGES and * pageblock_nr_pages pages. This: - * - Simplifies our fake page onlining code (virtio_mem_fake_online). * - Is required for now for alloc_contig_range() to work reliably - * it doesn't properly handle smaller granularity on ZONE_NORMAL. */
