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Date: Wed, 2 Jun 2021 20:57:17 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: David Hildenbrand <david@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Marek Kedzierski <mkedzier@...hat.com>,
Hui Zhu <teawater@...il.com>,
Pankaj Gupta <pankaj.gupta.linux@...il.com>,
Wei Yang <richard.weiyang@...ux.alibaba.com>,
Oscar Salvador <osalvador@...e.de>,
Michal Hocko <mhocko@...nel.org>,
virtualization@...ts.linux-foundation.org, linux-mm@...ck.org
Subject: [PATCH v1 4/7] virtio-mem: simplify high-level unplug handling in Sub Block Mode
Let's simplify by introducing a new virtio_mem_sbm_unplug_any_sb(),
similar to virtio_mem_sbm_plug_any_sb(), to simplify high-level memory
block selection when unplugging in Sub Block Mode.
Rename existing virtio_mem_sbm_unplug_any_sb() to
virtio_mem_sbm_unplug_any_sb_raw().
The only change is that we now temporarily unlock the hotplug mutex around
cond_resched() when processing offline memory blocks, which doesn't
make a real difference as we already have to temporarily unlock in
virtio_mem_sbm_unplug_any_sb_offline() when removing a memory block.
Signed-off-by: David Hildenbrand <david@...hat.com>
---
drivers/virtio/virtio_mem.c | 103 ++++++++++++++++++++----------------
1 file changed, 57 insertions(+), 46 deletions(-)
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index c0e6ea6244e4..d54bb34a7ed8 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1453,8 +1453,8 @@ static int virtio_mem_bbm_plug_bb(struct virtio_mem *vm, unsigned long bb_id)
*
* Note: can fail after some subblocks were unplugged.
*/
-static int virtio_mem_sbm_unplug_any_sb(struct virtio_mem *vm,
- unsigned long mb_id, uint64_t *nb_sb)
+static int virtio_mem_sbm_unplug_any_sb_raw(struct virtio_mem *vm,
+ unsigned long mb_id, uint64_t *nb_sb)
{
int sb_id, count;
int rc;
@@ -1496,7 +1496,7 @@ static int virtio_mem_sbm_unplug_mb(struct virtio_mem *vm, unsigned long mb_id)
{
uint64_t nb_sb = vm->sbm.sbs_per_mb;
- return virtio_mem_sbm_unplug_any_sb(vm, mb_id, &nb_sb);
+ return virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, &nb_sb);
}
/*
@@ -1806,7 +1806,7 @@ static int virtio_mem_sbm_unplug_any_sb_offline(struct virtio_mem *vm,
{
int rc;
- rc = virtio_mem_sbm_unplug_any_sb(vm, mb_id, nb_sb);
+ rc = virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, nb_sb);
/* some subblocks might have been unplugged even on failure */
if (!virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
@@ -1929,11 +1929,46 @@ static int virtio_mem_sbm_unplug_any_sb_online(struct virtio_mem *vm,
return 0;
}
+/*
+ * Unplug the desired number of plugged subblocks of a memory block that is
+ * already added to Linux. Will skip subblock of online memory blocks that are
+ * busy (by the OS). Will fail if any subblock that's not busy cannot get
+ * unplugged.
+ *
+ * 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.
+ */
+static int virtio_mem_sbm_unplug_any_sb(struct virtio_mem *vm,
+ unsigned long mb_id,
+ uint64_t *nb_sb)
+{
+ const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
+
+ switch (old_state) {
+ case VIRTIO_MEM_SBM_MB_ONLINE_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_ONLINE:
+ return virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, nb_sb);
+ case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
+ case VIRTIO_MEM_SBM_MB_OFFLINE:
+ return virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, nb_sb);
+ }
+ return -EINVAL;
+}
+
static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
+ const int mb_states[] = {
+ VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_OFFLINE,
+ VIRTIO_MEM_SBM_MB_ONLINE_PARTIAL,
+ VIRTIO_MEM_SBM_MB_ONLINE,
+ };
uint64_t nb_sb = diff / vm->sbm.sb_size;
unsigned long mb_id;
- int rc;
+ int rc, i;
if (!nb_sb)
return 0;
@@ -1945,47 +1980,23 @@ static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
*/
mutex_lock(&vm->hotplug_mutex);
- /* Try to unplug subblocks of partially plugged offline blocks. */
- virtio_mem_sbm_for_each_mb_rev(vm, mb_id,
- VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL) {
- rc = virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, &nb_sb);
- if (rc || !nb_sb)
- goto out_unlock;
- cond_resched();
- }
-
- /* Try to unplug subblocks of plugged offline blocks. */
- virtio_mem_sbm_for_each_mb_rev(vm, mb_id, VIRTIO_MEM_SBM_MB_OFFLINE) {
- rc = virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, &nb_sb);
- if (rc || !nb_sb)
- goto out_unlock;
- cond_resched();
- }
-
- if (!unplug_online) {
- mutex_unlock(&vm->hotplug_mutex);
- return 0;
- }
-
- /* Try to unplug subblocks of partially plugged online blocks. */
- virtio_mem_sbm_for_each_mb_rev(vm, mb_id,
- VIRTIO_MEM_SBM_MB_ONLINE_PARTIAL) {
- rc = virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, &nb_sb);
- if (rc || !nb_sb)
- goto out_unlock;
- mutex_unlock(&vm->hotplug_mutex);
- cond_resched();
- mutex_lock(&vm->hotplug_mutex);
- }
-
- /* Try to unplug subblocks of plugged online blocks. */
- virtio_mem_sbm_for_each_mb_rev(vm, mb_id, VIRTIO_MEM_SBM_MB_ONLINE) {
- rc = virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, &nb_sb);
- if (rc || !nb_sb)
- goto out_unlock;
- mutex_unlock(&vm->hotplug_mutex);
- cond_resched();
- mutex_lock(&vm->hotplug_mutex);
+ /*
+ * We try unplug from partially plugged blocks first, to try removing
+ * whole memory blocks along with metadata.
+ */
+ for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
+ virtio_mem_sbm_for_each_mb_rev(vm, mb_id, mb_states[i]) {
+ rc = virtio_mem_sbm_unplug_any_sb(vm, mb_id, &nb_sb);
+ if (rc || !nb_sb)
+ goto out_unlock;
+ mutex_unlock(&vm->hotplug_mutex);
+ cond_resched();
+ mutex_lock(&vm->hotplug_mutex);
+ }
+ if (!unplug_online && i == 1) {
+ mutex_unlock(&vm->hotplug_mutex);
+ return 0;
+ }
}
mutex_unlock(&vm->hotplug_mutex);
--
2.31.1
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