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authorDavid Hildenbrand <david@redhat.com>2020-11-12 14:37:56 +0100
committerMichael S. Tsirkin <mst@redhat.com>2020-12-18 16:14:26 -0500
commitf2d799d591359685a3a74d28c2989c56f4bb9898 (patch)
treec3612f771eb0ac45066ccf684544796eb5074cf6 /drivers/virtio
parent7a34c77dab7e0c7ecb58da8bf600b7aadb4d878c (diff)
virtio-mem: retry fake-offlining via alloc_contig_range() on ZONE_MOVABLE
ZONE_MOVABLE is supposed to give some guarantees, yet, alloc_contig_range() isn't prepared to properly deal with some racy cases properly (e.g., temporary page pinning when exiting processed, PCP). Retry 5 times for now. There is certainly room for improvement in the future. Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20201112133815.13332-11-david@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_mem.c37
1 files changed, 26 insertions, 11 deletions
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index c24055248f9d..2f1ce4d4781b 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -784,19 +784,34 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
*/
static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages)
{
- int rc;
+ const bool is_movable = zone_idx(page_zone(pfn_to_page(pfn))) ==
+ ZONE_MOVABLE;
+ int rc, retry_count;
- rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
- GFP_KERNEL);
- if (rc == -ENOMEM)
- /* whoops, out of memory */
- return rc;
- if (rc)
- return -EBUSY;
+ /*
+ * TODO: We want an alloc_contig_range() mode that tries to allocate
+ * harder (e.g., dealing with temporarily pinned pages, PCP), especially
+ * with ZONE_MOVABLE. So for now, retry a couple of times with
+ * ZONE_MOVABLE before giving up - because that zone is supposed to give
+ * some guarantees.
+ */
+ for (retry_count = 0; retry_count < 5; retry_count++) {
+ rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
+ GFP_KERNEL);
+ if (rc == -ENOMEM)
+ /* whoops, out of memory */
+ return rc;
+ else if (rc && !is_movable)
+ break;
+ else if (rc)
+ continue;
- virtio_mem_set_fake_offline(pfn, nr_pages, true);
- adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
- return 0;
+ virtio_mem_set_fake_offline(pfn, nr_pages, true);
+ adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
+ return 0;
+ }
+
+ return -EBUSY;
}
/*