LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: David Hildenbrand <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 <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Oscar Salvador <osalvador@suse.de>,
	Igor Mammedov <imammedo@redhat.com>,
	Dave Young <dyoung@redhat.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v2 08/10] virtio-mem: Offline and remove completely unplugged memory blocks
Date: Wed, 11 Mar 2020 18:14:20 +0100	[thread overview]
Message-ID: <20200311171422.10484-9-david@redhat.com> (raw)
In-Reply-To: <20200311171422.10484-1-david@redhat.com>

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;
 }
 
-- 
2.24.1


  parent reply	other threads:[~2020-03-11 17:16 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 17:14 [PATCH v2 00/10] virtio-mem: paravirtualized memory David Hildenbrand
2020-03-11 17:14 ` [PATCH v2 01/10] virtio-mem: Paravirtualized memory hotplug David Hildenbrand
2020-04-15  5:59   ` Pankaj Gupta
2020-03-11 17:14 ` [PATCH v2 02/10] virtio-mem: Allow to specify an ACPI PXM as nid David Hildenbrand
2020-03-30 11:04   ` Pankaj Gupta
2020-03-11 17:14 ` [PATCH v2 03/10] virtio-mem: Paravirtualized memory hotunplug part 1 David Hildenbrand
2020-03-11 17:14 ` [PATCH v2 04/10] virtio-mem: Paravirtualized memory hotunplug part 2 David Hildenbrand
2020-03-11 17:14 ` [PATCH v2 05/10] mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE David Hildenbrand
2020-04-14 16:34   ` Michael S. Tsirkin
2020-04-15  0:32     ` Andrew Morton
2020-03-11 17:14 ` [PATCH v2 06/10] virtio-mem: Allow to offline partially unplugged memory blocks David Hildenbrand
2020-03-11 17:14 ` [PATCH v2 07/10] mm/memory_hotplug: Introduce offline_and_remove_memory() David Hildenbrand
2020-03-11 17:19   ` David Hildenbrand
2020-04-14 16:35     ` Michael S. Tsirkin
2020-04-15  0:30       ` Andrew Morton
2020-04-15  7:35   ` Pankaj Gupta
2020-03-11 17:14 ` David Hildenbrand [this message]
2020-04-15  7:42   ` [PATCH v2 08/10] virtio-mem: Offline and remove completely unplugged memory blocks Pankaj Gupta
2020-03-11 17:14 ` [PATCH v2 09/10] virtio-mem: Better retry handling David Hildenbrand
2020-03-11 17:14 ` [PATCH v2 10/10] MAINTAINERS: Add myself as virtio-mem maintainer David Hildenbrand
2020-03-27 16:58 ` [PATCH v2 00/10] virtio-mem: paravirtualized memory Pankaj Gupta
2020-03-27 17:03   ` David Hildenbrand
2020-03-27 17:07     ` David Hildenbrand
2020-03-29 15:41     ` Pankaj Gupta
2020-03-30  8:42       ` David Hildenbrand
2020-03-29 12:42 ` Michael S. Tsirkin
2020-03-30  8:16   ` David Hildenbrand
2020-04-14  9:15   ` David Hildenbrand
2020-04-14 16:28     ` Michael S. Tsirkin
2020-04-14 18:39       ` David Hildenbrand

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200311171422.10484-9-david@redhat.com \
    --to=david@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=dan.j.williams@intel.com \
    --cc=dyoung@redhat.com \
    --cc=imammedo@redhat.com \
    --cc=jasowang@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mst@redhat.com \
    --cc=osalvador@suse.de \
    --cc=pasha.tatashin@soleen.com \
    --cc=stefanha@redhat.com \
    --cc=vbabka@suse.cz \
    --cc=virtio-dev@lists.oasis-open.org \
    --cc=virtualization@lists.linux-foundation.org \
    --subject='Re: [PATCH v2 08/10] virtio-mem: Offline and remove completely unplugged memory blocks' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).