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| author | David Hildenbrand <david@redhat.com> | 2020-11-12 16:37:56 +0300 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2020-12-19 00:14:26 +0300 |
| commit | f2d799d591359685a3a74d28c2989c56f4bb9898 (patch) | |
| tree | c3612f771eb0ac45066ccf684544796eb5074cf6 | |
| parent | 7a34c77dab7e0c7ecb58da8bf600b7aadb4d878c (diff) | |
| download | linux-f2d799d591359685a3a74d28c2989c56f4bb9898.tar.xz | |
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>
| -rw-r--r-- | drivers/virtio/virtio_mem.c | 37 |
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; } /* |