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[79.178.2.19]) by smtp.gmail.com with ESMTPSA id e130sm23973211qkb.72.2020.03.10.04.19.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2020 04:19:18 -0700 (PDT) Date: Tue, 10 Mar 2020 07:19:13 -0400 From: "Michael S. Tsirkin" To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, Jason Wang , Stephen Rothwell , Tyler Sanderson , Wei Wang , Alexander Duyck , David Rientjes , Nadav Amit , Michal Hocko , Andrew Morton Subject: Re: [PATCH v2] virtio-balloon: Switch back to OOM handler for VIRTIO_BALLOON_F_DEFLATE_ON_OOM Message-ID: <20200310071844-mutt-send-email-mst@kernel.org> References: <20200310103903.6014-1-david@redhat.com> <20200310070413-mutt-send-email-mst@kernel.org> <78427916-fc17-b081-6b1e-cbcb00d51752@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <78427916-fc17-b081-6b1e-cbcb00d51752@redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 10, 2020 at 12:12:50PM +0100, David Hildenbrand wrote: > >> static void virtio_balloon_unregister_shrinker(struct virtio_balloon *vb) > >> @@ -971,7 +950,22 @@ static int virtballoon_probe(struct virtio_device *vdev) > >> VIRTIO_BALLOON_CMD_ID_STOP); > >> spin_lock_init(&vb->free_page_list_lock); > >> INIT_LIST_HEAD(&vb->free_page_list); > >> + /* > >> + * We're allowed to reuse any free pages, even if they are > >> + * still to be processed by the host. > >> + */ > >> + err = virtio_balloon_register_shrinker(vb); > >> + if (err) > >> + goto out_del_balloon_wq; > >> } > >> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { > >> + vb->oom_nb.notifier_call = virtio_balloon_oom_notify; > >> + vb->oom_nb.priority = VIRTIO_BALLOON_OOM_NOTIFY_PRIORITY; > >> + err = register_oom_notifier(&vb->oom_nb); > >> + if (err < 0) > >> + goto out_unregister_shrinker; > >> + } > >> + > > > > > > Let's decide whether we want an empty line after }, or not, and stick to > > it. I prefer an empty line but no biggie as long as we are consistent. > > Can add one. > > > > >> if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) { > >> /* Start with poison val of 0 representing general init */ > >> __u32 poison_val = 0; > >> @@ -986,15 +980,6 @@ static int virtballoon_probe(struct virtio_device *vdev) > >> virtio_cwrite(vb->vdev, struct virtio_balloon_config, > >> poison_val, &poison_val); > >> } > >> - /* > >> - * We continue to use VIRTIO_BALLOON_F_DEFLATE_ON_OOM to decide if a > >> - * shrinker needs to be registered to relieve memory pressure. > >> - */ > >> - if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) { > >> - err = virtio_balloon_register_shrinker(vb); > >> - if (err) > >> - goto out_del_balloon_wq; > >> - } > >> > >> vb->pr_dev_info.report = virtballoon_free_page_report; > >> if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_REPORTING)) { > >> @@ -1003,12 +988,12 @@ static int virtballoon_probe(struct virtio_device *vdev) > >> capacity = virtqueue_get_vring_size(vb->reporting_vq); > >> if (capacity < PAGE_REPORTING_CAPACITY) { > >> err = -ENOSPC; > >> - goto out_unregister_shrinker; > >> + goto out_unregister_oom; > >> } > >> > >> err = page_reporting_register(&vb->pr_dev_info); > >> if (err) > >> - goto out_unregister_shrinker; > >> + goto out_unregister_oom; > >> } > >> > >> virtio_device_ready(vdev); > >> @@ -1017,8 +1002,11 @@ static int virtballoon_probe(struct virtio_device *vdev) > >> virtballoon_changed(vdev); > >> return 0; > >> > >> +out_unregister_oom: > >> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) > >> + unregister_oom_notifier(&vb->oom_nb); > >> out_unregister_shrinker: > >> - if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_DEFLATE_ON_OOM)) > >> + if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) > >> virtio_balloon_unregister_shrinker(vb); > > > > > > What's with vdev versus vb->vdev here? > > I suggest we keep using vb->vdev to make the patch minimal if we can. > > Same elsewhere. > > As we touch this line either way, does it really make a difference? No > strong opinion. Can just do a vb->vdev and clean this up globally later. > Let's just be consistent. I guess that means keep using vb->vdev everywhere. > -- > Thanks, > > David / dhildenb