From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [PATCH v2 08/10] virtio-mem: Offline and remove completely unplugged memory blocks Date: Wed, 11 Mar 2020 18:14:20 +0100 Message-ID: <20200311171422.10484-9-david@redhat.com> References: <20200311171422.10484-1-david@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: In-Reply-To: <20200311171422.10484-1-david@redhat.com> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Jason Wang , Oscar Salvador , Igor Mammedov , Dave Young , Dan Williams , Pavel Tatashin , Stefan Hajnoczi , Vlastimil Babka List-Id: virtualization@lists.linuxfoundation.org Let's offline+remove memory blocks once all subblocks are unplugged. We can use the new Linux MM interface for that. As no memory is in use anymore, this shouldn't take a long time and shouldn't fail. There might be corner cases where the offlining could still fail (especially, if another notifier NACKs the offlining request). Cc: "Michael S. Tsirkin" Cc: Jason Wang Cc: Oscar Salvador Cc: Michal Hocko Cc: Igor Mammedov Cc: Dave Young Cc: Andrew Morton Cc: Dan Williams Cc: Pavel Tatashin Cc: Stefan Hajnoczi Cc: Vlastimil Babka Signed-off-by: David Hildenbrand --- drivers/virtio/virtio_mem.c | 47 +++++++++++++++++++++++++++++++++---- 1 file changed, 43 insertions(+), 4 deletions(-) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 35f20232770c..aa322e7732a4 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -443,6 +443,28 @@ static int virtio_mem_mb_remove(struct virtio_mem *v= m, unsigned long mb_id) return remove_memory(nid, addr, memory_block_size_bytes()); } =20 +/* + * Try to offline and remove a memory block from Linux. + * + * Must not be called with the vm->hotplug_mutex held (possible deadlock= with + * onlining code). + * + * Will not modify the state of the memory block. + */ +static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm, + unsigned long mb_id) +{ + const uint64_t addr =3D virtio_mem_mb_id_to_phys(mb_id); + int nid =3D vm->nid; + + if (nid =3D=3D NUMA_NO_NODE) + nid =3D memory_add_physaddr_to_nid(addr); + + dev_dbg(&vm->vdev->dev, "offlining and removing memory block: %lu\n", + mb_id); + return offline_and_remove_memory(nid, addr, memory_block_size_bytes()); +} + /* * Trigger the workqueue so the device can perform its magic. */ @@ -535,7 +557,13 @@ static void virtio_mem_notify_offline(struct virtio_= mem *vm, break; } =20 - /* trigger the workqueue, maybe we can now unplug memory. */ + /* + * Trigger the workqueue, maybe we can now unplug memory. Also, + * when we offline and remove a memory block, this will re-trigger + * us immediately - which is often nice because the removal of + * the memory block (e.g., memmap) might have freed up memory + * on other memory blocks we manage. + */ virtio_mem_retry(vm); } =20 @@ -1282,7 +1310,8 @@ static int virtio_mem_mb_unplug_any_sb_offline(stru= ct virtio_mem *vm, * Unplug the desired number of plugged subblocks of an online memory bl= ock. * Will skip subblock that are busy. * - * Will modify the state of the memory block. + * Will modify the state of the memory block. Might temporarily drop the + * hotplug_mutex. * * Note: Can fail after some subblocks were successfully unplugged. Can * return 0 even if subblocks were busy and could not get unplugge= d. @@ -1338,9 +1367,19 @@ static int virtio_mem_mb_unplug_any_sb_online(stru= ct virtio_mem *vm, } =20 /* - * TODO: Once all subblocks of a memory block were unplugged, we want - * to offline the memory block and remove it. + * Once all subblocks of a memory block were unplugged, offline and + * remove it. This will usually not fail, as no memory is in use + * anymore - however some other notifiers might NACK the request. */ + if (virtio_mem_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_per_mb)) { + mutex_unlock(&vm->hotplug_mutex); + rc =3D virtio_mem_mb_offline_and_remove(vm, mb_id); + mutex_lock(&vm->hotplug_mutex); + if (!rc) + virtio_mem_mb_set_state(vm, mb_id, + VIRTIO_MEM_MB_STATE_UNUSED); + } + return 0; } =20 --=20 2.24.1