From: Wei Yang <richard.weiyang@linux.alibaba.com>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
virtualization@lists.linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
"Michael S . Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Michal Hocko <mhocko@kernel.org>,
Oscar Salvador <osalvador@suse.de>,
Wei Yang <richard.weiyang@linux.alibaba.com>
Subject: Re: [PATCH v1 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug
Date: Mon, 19 Oct 2020 11:48:17 +0800 [thread overview]
Message-ID: <20201019034817.GD54484@L-31X9LVDL-1304.local> (raw)
In-Reply-To: <20201012125323.17509-29-david@redhat.com>
On Mon, Oct 12, 2020 at 02:53:22PM +0200, David Hildenbrand wrote:
>Let's try to unplug completely offline big blocks first. Then, (if
>enabled via unplug_offline) try to offline and remove whole big blocks.
>
>No locking necessary - we can deal with concurrent onlining/offlining
>just fine.
>
>Note1: This is sub-optimal and might be dangerous in some environments: we
>could end up in an infinite loop when offlining (e.g., long-term pinnings),
>similar as with DIMMs. We'll introduce safe memory hotunplug via
>fake-offlining next, and use this basic mode only when explicitly enabled.
>
>Note2: Without ZONE_MOVABLE, memory unplug will be extremely unreliable
>with bigger block sizes.
>
>Cc: "Michael S. Tsirkin" <mst@redhat.com>
>Cc: Jason Wang <jasowang@redhat.com>
>Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
>Cc: Michal Hocko <mhocko@kernel.org>
>Cc: Oscar Salvador <osalvador@suse.de>
>Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
>Cc: Andrew Morton <akpm@linux-foundation.org>
>Signed-off-by: David Hildenbrand <david@redhat.com>
>---
> drivers/virtio/virtio_mem.c | 156 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 155 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
>index 94cf44b15cbf..6bcd0acbff32 100644
>--- a/drivers/virtio/virtio_mem.c
>+++ b/drivers/virtio/virtio_mem.c
>@@ -388,6 +388,12 @@ static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
> _bb_id++) \
> if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
>
>+#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \
>+ for (_bb_id = vm->bbm.next_bb_id - 1; \
>+ _bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \
>+ _bb_id--) \
>+ if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
>+
> /*
> * Set the state of a memory block, taking care of the state counter.
> */
>@@ -685,6 +691,18 @@ static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
> return virtio_mem_remove_memory(vm, addr, size);
> }
>
>+/*
>+ * See virtio_mem_remove_memory(): Try to remove all Linux memory blocks covered
>+ * by the big block.
>+ */
>+static int virtio_mem_bbm_remove_bb(struct virtio_mem *vm, unsigned long bb_id)
>+{
>+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
>+ const uint64_t size = vm->bbm.bb_size;
>+
>+ return virtio_mem_remove_memory(vm, addr, size);
>+}
>+
> /*
> * Try offlining and removing memory from Linux.
> *
>@@ -731,6 +749,19 @@ static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
> return virtio_mem_offline_and_remove_memory(vm, addr, size);
> }
>
>+/*
>+ * See virtio_mem_offline_and_remove_memory(): Try to offline and remove a
>+ * all Linux memory blocks covered by the big block.
>+ */
>+static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm,
>+ unsigned long bb_id)
>+{
>+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
>+ const uint64_t size = vm->bbm.bb_size;
>+
>+ return virtio_mem_offline_and_remove_memory(vm, addr, size);
>+}
>+
> /*
> * Trigger the workqueue so the device can perform its magic.
> */
>@@ -1928,6 +1959,129 @@ static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
> return rc;
> }
>
>+/*
>+ * Try to offline and remove a big block from Linux and unplug it. Will fail
>+ * with -EBUSY if some memory is busy and cannot get unplugged.
>+ *
>+ * Will modify the state of the memory block. Might temporarily drop the
>+ * hotplug_mutex.
>+ */
>+static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
>+ unsigned long bb_id)
>+{
>+ int rc;
>+
>+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
>+ VIRTIO_MEM_BBM_BB_ADDED))
>+ return -EINVAL;
>+
>+ rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id);
>+ if (rc)
>+ return rc;
>+
>+ rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
>+ if (rc)
>+ virtio_mem_bbm_set_bb_state(vm, bb_id,
>+ VIRTIO_MEM_BBM_BB_PLUGGED);
>+ else
>+ virtio_mem_bbm_set_bb_state(vm, bb_id,
>+ VIRTIO_MEM_BBM_BB_UNUSED);
>+ return rc;
>+}
>+
>+/*
>+ * Try to remove a big block from Linux and unplug it. Will fail with
>+ * -EBUSY if some memory is online.
>+ *
>+ * Will modify the state of the memory block.
>+ */
>+static int virtio_mem_bbm_remove_and_unplug_bb(struct virtio_mem *vm,
>+ unsigned long bb_id)
>+{
>+ int rc;
>+
>+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
>+ VIRTIO_MEM_BBM_BB_ADDED))
>+ return -EINVAL;
>+
>+ rc = virtio_mem_bbm_remove_bb(vm, bb_id);
>+ if (rc)
>+ return -EBUSY;
>+
>+ rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
>+ if (rc)
>+ virtio_mem_bbm_set_bb_state(vm, bb_id,
>+ VIRTIO_MEM_BBM_BB_PLUGGED);
>+ else
>+ virtio_mem_bbm_set_bb_state(vm, bb_id,
>+ VIRTIO_MEM_BBM_BB_UNUSED);
>+ return rc;
>+}
>+
>+/*
>+ * Test if a big block is completely offline.
>+ */
>+static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm,
>+ unsigned long bb_id)
>+{
>+ const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
>+ const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
>+ unsigned long pfn;
>+
>+ for (pfn = start_pfn; pfn < start_pfn + nr_pages;
>+ pfn += PAGES_PER_SECTION) {
Can we do the check with memory block granularity?
>+ if (pfn_to_online_page(pfn))
>+ return false;
>+ }
>+
>+ return true;
>+}
>+
>+static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
>+{
>+ uint64_t nb_bb = diff / vm->bbm.bb_size;
>+ uint64_t bb_id;
>+ int rc;
>+
>+ if (!nb_bb)
>+ return 0;
>+
>+ /* Try to unplug completely offline big blocks first. */
>+ virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) {
>+ cond_resched();
>+ /*
>+ * As we're holding no locks, this check is racy as memory
>+ * can get onlined in the meantime - but we'll fail gracefully.
>+ */
>+ if (!virtio_mem_bbm_bb_is_offline(vm, bb_id))
>+ continue;
>+ rc = virtio_mem_bbm_remove_and_unplug_bb(vm, bb_id);
>+ if (rc == -EBUSY)
>+ continue;
>+ if (!rc)
>+ nb_bb--;
>+ if (rc || !nb_bb)
>+ return rc;
>+ }
>+
>+ if (!unplug_online)
>+ return 0;
>+
>+ /* Try to unplug any big blocks. */
>+ virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) {
>+ cond_resched();
>+ rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id);
>+ if (rc == -EBUSY)
>+ continue;
>+ if (!rc)
>+ nb_bb--;
>+ if (rc || !nb_bb)
>+ return rc;
>+ }
>+
>+ return nb_bb ? -EBUSY : 0;
>+}
>+
> /*
> * Try to unplug the requested amount of memory.
> */
>@@ -1935,7 +2089,7 @@ static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
> {
> if (vm->in_sbm)
> return virtio_mem_sbm_unplug_request(vm, diff);
>- return -EBUSY;
>+ return virtio_mem_bbm_unplug_request(vm, diff);
> }
>
> /*
>--
>2.26.2
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2020-10-19 3:48 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 12:52 [PATCH v1 00/29] virtio-mem: Big Block Mode (BBM) David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 01/29] virtio-mem: determine nid only once using memory_add_physaddr_to_nid() David Hildenbrand
2020-10-15 3:56 ` Wei Yang
2020-10-15 19:26 ` Pankaj Gupta
2020-10-12 12:52 ` [PATCH v1 02/29] virtio-mem: simplify calculation in virtio_mem_mb_state_prepare_next_mb() David Hildenbrand
2020-10-15 4:02 ` Wei Yang
2020-10-15 8:00 ` David Hildenbrand
2020-10-15 10:00 ` Wei Yang
2020-10-15 10:01 ` David Hildenbrand
2020-10-15 20:24 ` Pankaj Gupta
2020-10-16 9:00 ` David Hildenbrand
2020-10-12 12:52 ` [PATCH v1 03/29] virtio-mem: simplify MAX_ORDER - 1 / pageblock_order handling David Hildenbrand
2020-10-15 7:06 ` Wei Yang
2020-10-12 12:52 ` [PATCH v1 04/29] virtio-mem: drop rc2 in virtio_mem_mb_plug_and_add() David Hildenbrand
2020-10-12 13:09 ` Pankaj Gupta
2020-10-15 7:14 ` Wei Yang
2020-10-12 12:52 ` [PATCH v1 05/29] virtio-mem: generalize check for added memory David Hildenbrand
2020-10-15 8:28 ` Wei Yang
2020-10-15 8:50 ` David Hildenbrand
2020-10-16 2:16 ` Wei Yang
2020-10-16 9:11 ` David Hildenbrand
2020-10-16 10:02 ` Wei Yang
2020-10-16 10:32 ` David Hildenbrand
2020-10-16 22:38 ` Wei Yang
2020-10-17 7:39 ` David Hildenbrand
2020-10-18 12:27 ` Wei Yang
2020-10-16 22:39 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 06/29] virtio-mem: generalize virtio_mem_owned_mb() David Hildenbrand
2020-10-15 8:32 ` Wei Yang
2020-10-15 8:37 ` David Hildenbrand
2020-10-15 20:30 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 07/29] virtio-mem: generalize virtio_mem_overlaps_range() David Hildenbrand
2020-10-20 9:22 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 08/29] virtio-mem: drop last_mb_id David Hildenbrand
2020-10-15 8:35 ` Wei Yang
2020-10-15 20:32 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 09/29] virtio-mem: don't always trigger the workqueue when offlining memory David Hildenbrand
2020-10-16 4:03 ` Wei Yang
2020-10-16 9:18 ` David Hildenbrand
2020-10-18 3:57 ` Wei Yang
2020-10-19 9:04 ` David Hildenbrand
2020-10-20 0:41 ` Wei Yang
2020-10-20 9:09 ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 10/29] virtio-mem: generalize handling when memory is getting onlined deferred David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 11/29] virtio-mem: use "unsigned long" for nr_pages when fake onlining/offlining David Hildenbrand
2020-10-15 20:31 ` Pankaj Gupta
2020-10-16 6:11 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 12/29] virtio-mem: factor out fake-offlining into virtio_mem_fake_offline() David Hildenbrand
2020-10-16 6:24 ` Wei Yang
2020-10-20 9:31 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 13/29] virtio-mem: factor out handling of fake-offline pages in memory notifier David Hildenbrand
2020-10-16 7:15 ` Wei Yang
2020-10-16 8:00 ` Wei Yang
2020-10-16 8:57 ` David Hildenbrand
2020-10-18 12:37 ` Wei Yang
2020-10-18 12:38 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 14/29] virtio-mem: retry fake-offlining via alloc_contig_range() on ZONE_MOVABLE David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 15/29] virito-mem: document Sub Block Mode (SBM) David Hildenbrand
2020-10-15 9:33 ` David Hildenbrand
2020-10-20 9:38 ` Pankaj Gupta
2020-10-16 8:03 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 16/29] virtio-mem: memory block states are specific to " David Hildenbrand
2020-10-16 8:40 ` Wei Yang
2020-10-16 8:43 ` Wei Yang
2020-10-20 9:48 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 17/29] virito-mem: subblock " David Hildenbrand
2020-10-16 8:43 ` Wei Yang
2020-10-20 9:54 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 18/29] virtio-mem: factor out calculation of the bit number within the sb_states bitmap David Hildenbrand
2020-10-16 8:46 ` Wei Yang
2020-10-20 9:58 ` Pankaj Gupta
2020-10-12 12:53 ` [PATCH v1 19/29] virito-mem: existing (un)plug functions are specific to Sub Block Mode (SBM) David Hildenbrand
2020-10-16 8:49 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 20/29] virtio-mem: nb_sb_per_mb and subblock_size " David Hildenbrand
2020-10-16 8:51 ` Wei Yang
2020-10-16 8:53 ` Wei Yang
2020-10-16 13:17 ` David Hildenbrand
2020-10-18 12:41 ` Wei Yang
2020-10-19 11:57 ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 21/29] virtio-mem: memory notifier callbacks " David Hildenbrand
2020-10-19 1:57 ` Wei Yang
2020-10-19 10:22 ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 22/29] virtio-mem: memory block ids " David Hildenbrand
2020-10-16 8:54 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 23/29] virtio-mem: factor out adding/removing memory from Linux David Hildenbrand
2020-10-16 8:59 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 24/29] virtio-mem: print debug messages from virtio_mem_send_*_request() David Hildenbrand
2020-10-16 9:07 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 25/29] virtio-mem: Big Block Mode (BBM) memory hotplug David Hildenbrand
2020-10-16 9:38 ` Wei Yang
2020-10-16 13:13 ` David Hildenbrand
2020-10-19 2:26 ` Wei Yang
2020-10-19 9:15 ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 26/29] virtio-mem: allow to force Big Block Mode (BBM) and set the big block size David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block David Hildenbrand
2020-10-15 13:08 ` Michael S. Tsirkin
2020-10-19 3:22 ` Wei Yang
2020-10-12 12:53 ` [PATCH v1 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug David Hildenbrand
2020-10-19 3:48 ` Wei Yang [this message]
2020-10-19 9:12 ` David Hildenbrand
2020-10-12 12:53 ` [PATCH v1 29/29] virtio-mem: Big Block Mode (BBM) - safe " David Hildenbrand
2020-10-19 7:54 ` Wei Yang
2020-10-19 8:50 ` David Hildenbrand
2020-10-20 0:23 ` Wei Yang
2020-10-20 0:24 ` Wei Yang
2020-10-18 12:49 ` [PATCH v1 00/29] virtio-mem: Big Block Mode (BBM) Wei Yang
2020-10-18 15:29 ` Michael S. Tsirkin
2020-10-18 16:34 ` 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=20201019034817.GD54484@L-31X9LVDL-1304.local \
--to=richard.weiyang@linux.alibaba.com \
--cc=akpm@linux-foundation.org \
--cc=david@redhat.com \
--cc=jasowang@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=mst@redhat.com \
--cc=osalvador@suse.de \
--cc=pankaj.gupta.linux@gmail.com \
--cc=virtualization@lists.linux-foundation.org \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).