| Message ID | 20200311171422.10484-9-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-mem: paravirtualized memory | expand |
> 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" <mst@redhat.com> > Cc: Jason Wang <jasowang@redhat.com> > Cc: Oscar Salvador <osalvador@suse.de> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Igor Mammedov <imammedo@redhat.com> > Cc: Dave Young <dyoung@redhat.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Dan Williams <dan.j.williams@intel.com> > Cc: Pavel Tatashin <pasha.tatashin@soleen.com> > Cc: Stefan Hajnoczi <stefanha@redhat.com> > Cc: Vlastimil Babka <vbabka@suse.cz> > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > 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 *vm, unsigned long mb_id) > return remove_memory(nid, addr, memory_block_size_bytes()); > } > > +/* > + * 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 = virtio_mem_mb_id_to_phys(mb_id); > + int nid = vm->nid; > + > + if (nid == NUMA_NO_NODE) > + nid = 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; > } > > - /* 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); > } > > @@ -1282,7 +1310,8 @@ static int virtio_mem_mb_unplug_any_sb_offline(struct virtio_mem *vm, > * Unplug the desired number of plugged subblocks of an online memory block. > * 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 unplugged. > @@ -1338,9 +1367,19 @@ static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm, > } > > /* > - * 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 = 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; > } > Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> > --
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 *vm, unsigned long mb_id) return remove_memory(nid, addr, memory_block_size_bytes()); } +/* + * 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 = virtio_mem_mb_id_to_phys(mb_id); + int nid = vm->nid; + + if (nid == NUMA_NO_NODE) + nid = 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; } - /* 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); } @@ -1282,7 +1310,8 @@ static int virtio_mem_mb_unplug_any_sb_offline(struct virtio_mem *vm, * Unplug the desired number of plugged subblocks of an online memory block. * 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 unplugged. @@ -1338,9 +1367,19 @@ static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm, } /* - * 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 = 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; }
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" <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Dave Young <dyoung@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: David Hildenbrand <david@redhat.com> --- drivers/virtio/virtio_mem.c | 47 +++++++++++++++++++++++++++++++++---- 1 file changed, 43 insertions(+), 4 deletions(-)