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virtio-mem: Offline and remove completely unplugged memory blocks

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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).

Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Tested-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
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>
Link: https://lore.kernel.org/r/20200507140139.17083-10-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Hildenbrand 2020-05-07 16:01:33 +02:00 committed by Michael S. Tsirkin
parent 08b3acd7a6
commit a573238786
1 changed files with 43 additions and 4 deletions
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47
drivers/virtio/virtio_mem.c
View File

@ -446,6 +446,28 @@ 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.
*/
@ -537,7 +559,13 @@ 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);
}
@ -1284,7 +1312,8 @@ 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.
@ -1340,9 +1369,19 @@ 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;
}