The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d9e427f6ab8142d6868eb719e6a7851aafea56b6 Mon Sep 17 00:00:00 2001
From: Jan Stancek jstancek@redhat.com Date: Fri, 1 Dec 2017 10:50:28 +0100 Subject: [PATCH] virtio_balloon: fix increment of vb->num_pfns in fill_balloon()
commit c7cdff0e8647 ("virtio_balloon: fix deadlock on OOM") changed code to increment vb->num_pfns before call to set_page_pfns(), which used to happen only after.
This patch fixes boot hang for me on ppc64le KVM guests.
Fixes: c7cdff0e8647 ("virtio_balloon: fix deadlock on OOM") Cc: Michael S. Tsirkin mst@redhat.com Cc: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Cc: Michal Hocko mhocko@suse.com Cc: Wei Wang wei.w.wang@intel.com Cc: stable@vger.kernel.org Signed-off-by: Jan Stancek jstancek@redhat.com Signed-off-by: Michael S. Tsirkin mst@redhat.com
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 7960746f7597..a1fb52cb3f0a 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -174,13 +174,12 @@ static unsigned fill_balloon(struct virtio_balloon *vb, size_t num) while ((page = balloon_page_pop(&pages))) { balloon_page_enqueue(&vb->vb_dev_info, page);
- vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; - set_page_pfns(vb, vb->pfns + vb->num_pfns, page); vb->num_pages += VIRTIO_BALLOON_PAGES_PER_PAGE; if (!virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) adjust_managed_page_count(page, -1); + vb->num_pfns += VIRTIO_BALLOON_PAGES_PER_PAGE; }
num_allocated_pages = vb->num_pfns;