From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org, linux-mm@kvack.org,
"Michael S . Tsirkin" <mst@redhat.com>,
David Hildenbrand <david@redhat.com>,
Wei Yang <richard.weiyang@linux.alibaba.com>,
Jason Wang <jasowang@redhat.com>,
Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
Michal Hocko <mhocko@kernel.org>,
Oscar Salvador <osalvador@suse.de>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH v2 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block
Date: Thu, 12 Nov 2020 14:38:13 +0100 [thread overview]
Message-ID: <20201112133815.13332-28-david@redhat.com> (raw)
In-Reply-To: <20201112133815.13332-1-david@redhat.com>
virtio-mem soon wants to use offline_and_remove_memory() memory that
exceeds a single Linux memory block (memory_block_size_bytes()). Let's
remove that restriction.
Let's remember the old state and try to restore that if anything goes
wrong. While re-onlining can, in general, fail, it's highly unlikely to
happen (usually only when a notifier fails to allocate memory, and these
are rather rare).
This will be used by virtio-mem to offline+remove memory ranges that are
bigger than a single memory block - for example, with a device block
size of 1 GiB (e.g., gigantic pages in the hypervisor) and a Linux memory
block size of 128MB.
While we could compress the state into 2 bit, using 8 bit is much
easier.
This handling is similar, but different to acpi_scan_try_to_offline():
a) We don't try to offline twice. I am not sure if this CONFIG_MEMCG
optimization is still relevant - it should only apply to ZONE_NORMAL
(where we have no guarantees). If relevant, we can always add it.
b) acpi_scan_try_to_offline() simply onlines all memory in case
something goes wrong. It doesn't restore previous online type. Let's do
that, so we won't overwrite what e.g., user space configured.
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
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>
---
mm/memory_hotplug.c | 105 +++++++++++++++++++++++++++++++++++++-------
1 file changed, 89 insertions(+), 16 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b44d4c7ba73b..217080ca93e5 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1806,39 +1806,112 @@ int remove_memory(int nid, u64 start, u64 size)
}
EXPORT_SYMBOL_GPL(remove_memory);
+static int try_offline_memory_block(struct memory_block *mem, void *arg)
+{
+ uint8_t online_type = MMOP_ONLINE_KERNEL;
+ uint8_t **online_types = arg;
+ struct page *page;
+ int rc;
+
+ /*
+ * Sense the online_type via the zone of the memory block. Offlining
+ * with multiple zones within one memory block will be rejected
+ * by offlining code ... so we don't care about that.
+ */
+ page = pfn_to_online_page(section_nr_to_pfn(mem->start_section_nr));
+ if (page && zone_idx(page_zone(page)) == ZONE_MOVABLE)
+ online_type = MMOP_ONLINE_MOVABLE;
+
+ rc = device_offline(&mem->dev);
+ /*
+ * Default is MMOP_OFFLINE - change it only if offlining succeeded,
+ * so try_reonline_memory_block() can do the right thing.
+ */
+ if (!rc)
+ **online_types = online_type;
+
+ (*online_types)++;
+ /* Ignore if already offline. */
+ return rc < 0 ? rc : 0;
+}
+
+static int try_reonline_memory_block(struct memory_block *mem, void *arg)
+{
+ uint8_t **online_types = arg;
+ int rc;
+
+ if (**online_types != MMOP_OFFLINE) {
+ mem->online_type = **online_types;
+ rc = device_online(&mem->dev);
+ if (rc < 0)
+ pr_warn("%s: Failed to re-online memory: %d",
+ __func__, rc);
+ }
+
+ /* Continue processing all remaining memory blocks. */
+ (*online_types)++;
+ return 0;
+}
+
/*
- * Try to offline and remove a memory block. Might take a long time to
- * finish in case memory is still in use. Primarily useful for memory devices
- * that logically unplugged all memory (so it's no longer in use) and want to
- * offline + remove the memory block.
+ * Try to offline and remove memory. Might take a long time to finish in case
+ * memory is still in use. Primarily useful for memory devices that logically
+ * unplugged all memory (so it's no longer in use) and want to offline + remove
+ * that memory.
*/
int offline_and_remove_memory(int nid, u64 start, u64 size)
{
- struct memory_block *mem;
- int rc = -EINVAL;
+ const unsigned long mb_count = size / memory_block_size_bytes();
+ uint8_t *online_types, *tmp;
+ int rc;
if (!IS_ALIGNED(start, memory_block_size_bytes()) ||
- size != memory_block_size_bytes())
- return rc;
+ !IS_ALIGNED(size, memory_block_size_bytes()) || !size)
+ return -EINVAL;
+
+ /*
+ * We'll remember the old online type of each memory block, so we can
+ * try to revert whatever we did when offlining one memory block fails
+ * after offlining some others succeeded.
+ */
+ online_types = kmalloc_array(mb_count, sizeof(*online_types),
+ GFP_KERNEL);
+ if (!online_types)
+ return -ENOMEM;
+ /*
+ * Initialize all states to MMOP_OFFLINE, so when we abort processing in
+ * try_offline_memory_block(), we'll skip all unprocessed blocks in
+ * try_reonline_memory_block().
+ */
+ memset(online_types, MMOP_OFFLINE, mb_count);
lock_device_hotplug();
- mem = find_memory_block(__pfn_to_section(PFN_DOWN(start)));
- if (mem)
- rc = device_offline(&mem->dev);
- /* Ignore if the device is already offline. */
- if (rc > 0)
- rc = 0;
+
+ tmp = online_types;
+ rc = walk_memory_blocks(start, size, &tmp, try_offline_memory_block);
/*
- * In case we succeeded to offline the memory block, remove it.
+ * In case we succeeded to offline all memory, remove it.
* This cannot fail as it cannot get onlined in the meantime.
*/
if (!rc) {
rc = try_remove_memory(nid, start, size);
- WARN_ON_ONCE(rc);
+ if (rc)
+ pr_err("%s: Failed to remove memory: %d", __func__, rc);
+ }
+
+ /*
+ * Rollback what we did. While memory onlining might theoretically fail
+ * (nacked by a notifier), it barely ever happens.
+ */
+ if (rc) {
+ tmp = online_types;
+ walk_memory_blocks(start, size, &tmp,
+ try_reonline_memory_block);
}
unlock_device_hotplug();
+ kfree(online_types);
return rc;
}
EXPORT_SYMBOL_GPL(offline_and_remove_memory);
--
2.26.2
next prev parent reply other threads:[~2020-11-12 13:40 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-12 13:37 [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM) David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 01/29] virtio-mem: determine nid only once using memory_add_physaddr_to_nid() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 02/29] virtio-mem: more precise calculation in virtio_mem_mb_state_prepare_next_mb() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 03/29] virtio-mem: simplify MAX_ORDER - 1 / pageblock_order handling David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 04/29] virtio-mem: drop rc2 in virtio_mem_mb_plug_and_add() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 05/29] virtio-mem: use "unsigned long" for nr_pages when fake onlining/offlining David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 06/29] virtio-mem: factor out calculation of the bit number within the subblock bitmap David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 07/29] virtio-mem: print debug messages from virtio_mem_send_*_request() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 08/29] virtio-mem: factor out fake-offlining into virtio_mem_fake_offline() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 09/29] virtio-mem: factor out handling of fake-offline pages in memory notifier David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 10/29] virtio-mem: retry fake-offlining via alloc_contig_range() on ZONE_MOVABLE David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 11/29] virtio-mem: generalize check for added memory David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 12/29] virtio-mem: generalize virtio_mem_owned_mb() David Hildenbrand
2020-11-12 13:37 ` [PATCH v2 13/29] virtio-mem: generalize virtio_mem_overlaps_range() David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 14/29] virtio-mem: drop last_mb_id David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 15/29] virtio-mem: don't always trigger the workqueue when offlining memory David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 16/29] virtio-mem: generalize handling when memory is getting onlined deferred David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 17/29] virito-mem: document Sub Block Mode (SBM) David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 18/29] virtio-mem: memory block states are specific to " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 19/29] virito-mem: subblock " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 20/29] virtio-mem: nb_sb_per_mb and subblock_size " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 21/29] virtio-mem: memory block ids " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 22/29] virito-mem: existing (un)plug functions " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 23/29] virtio-mem: memory notifier callbacks " David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 24/29] virtio-mem: factor out adding/removing memory from Linux David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 25/29] virtio-mem: Big Block Mode (BBM) memory hotplug David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 26/29] virtio-mem: allow to force Big Block Mode (BBM) and set the big block size David Hildenbrand
2020-11-12 13:38 ` David Hildenbrand [this message]
2020-11-18 4:53 ` [PATCH v2 27/29] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block Andrew Morton
2020-11-18 8:59 ` David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 28/29] virtio-mem: Big Block Mode (BBM) - basic memory hotunplug David Hildenbrand
2020-11-12 13:38 ` [PATCH v2 29/29] virtio-mem: Big Block Mode (BBM) - safe " David Hildenbrand
2020-11-18 9:00 ` [PATCH v2 00/29] virtio-mem: Big Block Mode (BBM) Michael S. Tsirkin
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