[PATCH 5.7 145/204] nvme: fix deadlock in disconnect during scan_work and/or ana_work

Greg Kroah-Hartman
2020-08-20T12:57:03Z

From: Sagi Grimberg <sagi@grimberg.me>

[ Upstream commit ecca390e80561debbfdb4dc96bf94595136889fa ]

A deadlock happens in the following scenario with multipath:
1) scan_work(nvme0) detects a new nsid while nvme0
is an optimized path to it, path nvme1 happens to be
inaccessible.

2) Before scan_work is complete nvme0 disconnect is initiated
nvme_delete_ctrl_sync() sets nvme0 state to NVME_CTRL_DELETING

3) scan_work(1) attempts to submit IO,
but nvme_path_is_optimized() observes nvme0 is not LIVE.
Since nvme1 is a possible path IO is requeued and scan_work hangs.

--
Workqueue: nvme-wq nvme_scan_work [nvme_core]
kernel: Call Trace:
kernel: __schedule+0x2b9/0x6c0
kernel: schedule+0x42/0xb0
kernel: io_schedule+0x16/0x40
kernel: do_read_cache_page+0x438/0x830
kernel: read_cache_page+0x12/0x20
kernel: read_dev_sector+0x27/0xc0
kernel: read_lba+0xc1/0x220
kernel: efi_partition+0x1e6/0x708
kernel: check_partition+0x154/0x244
kernel: rescan_partitions+0xae/0x280
kernel: __blkdev_get+0x40f/0x560
kernel: blkdev_get+0x3d/0x140
kernel: __device_add_disk+0x388/0x480
kernel: device_add_disk+0x13/0x20
kernel: nvme_mpath_set_live+0x119/0x140 [nvme_core]
kernel: nvme_update_ns_ana_state+0x5c/0x60 [nvme_core]
kernel: nvme_set_ns_ana_state+0x1e/0x30 [nvme_core]
kernel: nvme_parse_ana_log+0xa1/0x180 [nvme_core]
kernel: nvme_mpath_add_disk+0x47/0x90 [nvme_core]
kernel: nvme_validate_ns+0x396/0x940 [nvme_core]
kernel: nvme_scan_work+0x24f/0x380 [nvme_core]
kernel: process_one_work+0x1db/0x380
kernel: worker_thread+0x249/0x400
kernel: kthread+0x104/0x140
--

4) Delete also hangs in flush_work(ctrl->scan_work)
from nvme_remove_namespaces().

Similiarly a deadlock with ana_work may happen: if ana_work has started
and calls nvme_mpath_set_live and device_add_disk, it will
trigger I/O. When we trigger disconnect I/O will block because
our accessible (optimized) path is disconnecting, but the alternate
path is inaccessible, so I/O blocks. Then disconnect tries to flush
the ana_work and hangs.

[ 605.550896] Workqueue: nvme-wq nvme_ana_work [nvme_core]
[ 605.552087] Call Trace:
[ 605.552683] __schedule+0x2b9/0x6c0
[ 605.553507] schedule+0x42/0xb0
[ 605.554201] io_schedule+0x16/0x40
[ 605.555012] do_read_cache_page+0x438/0x830
[ 605.556925] read_cache_page+0x12/0x20
[ 605.557757] read_dev_sector+0x27/0xc0
[ 605.558587] amiga_partition+0x4d/0x4c5
[ 605.561278] check_partition+0x154/0x244
[ 605.562138] rescan_partitions+0xae/0x280
[ 605.563076] __blkdev_get+0x40f/0x560
[ 605.563830] blkdev_get+0x3d/0x140
[ 605.564500] __device_add_disk+0x388/0x480
[ 605.565316] device_add_disk+0x13/0x20
[ 605.566070] nvme_mpath_set_live+0x5e/0x130 [nvme_core]
[ 605.567114] nvme_update_ns_ana_state+0x2c/0x30 [nvme_core]
[ 605.568197] nvme_update_ana_state+0xca/0xe0 [nvme_core]
[ 605.569360] nvme_parse_ana_log+0xa1/0x180 [nvme_core]
[ 605.571385] nvme_read_ana_log+0x76/0x100 [nvme_core]
[ 605.572376] nvme_ana_work+0x15/0x20 [nvme_core]
[ 605.573330] process_one_work+0x1db/0x380
[ 605.574144] worker_thread+0x4d/0x400
[ 605.574896] kthread+0x104/0x140
[ 605.577205] ret_from_fork+0x35/0x40
[ 605.577955] INFO: task nvme:14044 blocked for more than 120 seconds.
[ 605.579239] Tainted: G OE 5.3.5-050305-generic #201910071830
[ 605.580712] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 605.582320] nvme D 0 14044 14043 0x00000000
[ 605.583424] Call Trace:
[ 605.583935] __schedule+0x2b9/0x6c0
[ 605.584625] schedule+0x42/0xb0
[ 605.585290] schedule_timeout+0x203/0x2f0
[ 605.588493] wait_for_completion+0xb1/0x120
[ 605.590066] __flush_work+0x123/0x1d0
[ 605.591758] __cancel_work_timer+0x10e/0x190
[ 605.593542] cancel_work_sync+0x10/0x20
[ 605.594347] nvme_mpath_stop+0x2f/0x40 [nvme_core]
[ 605.595328] nvme_stop_ctrl+0x12/0x50 [nvme_core]
[ 605.596262] nvme_do_delete_ctrl+0x3f/0x90 [nvme_core]
[ 605.597333] nvme_sysfs_delete+0x5c/0x70 [nvme_core]
[ 605.598320] dev_attr_store+0x17/0x30

Fix this by introducing a new state: NVME_CTRL_DELETE_NOIO, which will
indicate the phase of controller deletion where I/O cannot be allowed
to access the namespace. NVME_CTRL_DELETING still allows mpath I/O to
be issued to the bottom device, and only after we flush the ana_work
and scan_work (after nvme_stop_ctrl and nvme_prep_remove_namespaces)
we change the state to NVME_CTRL_DELETING_NOIO. Also we prevent ana_work
from re-firing by aborting early if we are not LIVE, so we should be safe
here.

In addition, change the transport drivers to follow the updated state
machine.

Fixes: 0d0b660f214d ("nvme: add ANA support")
Reported-by: Anton Eidelman <anton@lightbitslabs.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/core.c | 15 +++++++++++++++
drivers/nvme/host/fabrics.c | 2 +-
drivers/nvme/host/fabrics.h | 3 ++-
drivers/nvme/host/fc.c | 1 +
drivers/nvme/host/multipath.c | 18 +++++++++++++++---
drivers/nvme/host/nvme.h | 1 +
drivers/nvme/host/rdma.c | 10 ++++++----
drivers/nvme/host/tcp.c | 15 +++++++++------
8 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f7540a9e54fd2..ee67113d96b1b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -368,6 +368,16 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
break;
}
break;
+ case NVME_CTRL_DELETING_NOIO:
+ switch (old_state) {
+ case NVME_CTRL_DELETING:
+ case NVME_CTRL_DEAD:
+ changed = true;
+ /* FALLTHRU */
+ default:
+ break;
+ }
+ break;
case NVME_CTRL_DEAD:
switch (old_state) {
case NVME_CTRL_DELETING:
@@ -405,6 +415,7 @@ static bool nvme_state_terminal(struct nvme_ctrl *ctrl)
case NVME_CTRL_CONNECTING:
return false;
case NVME_CTRL_DELETING:
+ case NVME_CTRL_DELETING_NOIO:
case NVME_CTRL_DEAD:
return true;
default:
@@ -3280,6 +3291,7 @@ static ssize_t nvme_sysfs_show_state(struct device *dev,
[NVME_CTRL_RESETTING] = "resetting",
[NVME_CTRL_CONNECTING] = "connecting",
[NVME_CTRL_DELETING] = "deleting",
+ [NVME_CTRL_DELETING_NOIO]= "deleting (no IO)",
[NVME_CTRL_DEAD] = "dead",
};

@@ -3860,6 +3872,9 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
if (ctrl->state == NVME_CTRL_DEAD)
nvme_kill_queues(ctrl);

+ /* this is a no-op when called from the controller reset handler */
+ nvme_change_ctrl_state(ctrl, NVME_CTRL_DELETING_NOIO);
+
down_write(&ctrl->namespaces_rwsem);
list_splice_init(&ctrl->namespaces, &ns_list);
up_write(&ctrl->namespaces_rwsem);
diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 2a6c8190eeb76..4ec4829d62334 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -547,7 +547,7 @@ static struct nvmf_transport_ops *nvmf_lookup_transport(
blk_status_t nvmf_fail_nonready_command(struct nvme_ctrl *ctrl,
struct request *rq)
{
- if (ctrl->state != NVME_CTRL_DELETING &&
+ if (ctrl->state != NVME_CTRL_DELETING_NOIO &&
ctrl->state != NVME_CTRL_DEAD &&
!blk_noretry_request(rq) && !(rq->cmd_flags & REQ_NVME_MPATH))
return BLK_STS_RESOURCE;
diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
index a0ec40ab62eeb..a9c1e3b4585ec 100644
--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -182,7 +182,8 @@ bool nvmf_ip_options_match(struct nvme_ctrl *ctrl,
static inline bool nvmf_check_ready(struct nvme_ctrl *ctrl, struct request *rq,
bool queue_live)
{
- if (likely(ctrl->state == NVME_CTRL_LIVE))
+ if (likely(ctrl->state == NVME_CTRL_LIVE ||
+ ctrl->state == NVME_CTRL_DELETING))
return true;
return __nvmf_check_ready(ctrl, rq, queue_live);
}
diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 564e3f220ac79..a70220df1f570 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -800,6 +800,7 @@ nvme_fc_ctrl_connectivity_loss(struct nvme_fc_ctrl *ctrl)
break;

case NVME_CTRL_DELETING:
+ case NVME_CTRL_DELETING_NOIO:
default:
/* no action to take - let it delete */
break;
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index d3914b7e8f52c..8f235fbfe44ee 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -167,9 +167,18 @@ void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl)

static bool nvme_path_is_disabled(struct nvme_ns *ns)
{
- return ns->ctrl->state != NVME_CTRL_LIVE ||
- test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
- test_bit(NVME_NS_REMOVING, &ns->flags);
+ /*
+ * We don't treat NVME_CTRL_DELETING as a disabled path as I/O should
+ * still be able to complete assuming that the controller is connected.
+ * Otherwise it will fail immediately and return to the requeue list.
+ */
+ if (ns->ctrl->state != NVME_CTRL_LIVE &&
+ ns->ctrl->state != NVME_CTRL_DELETING)
+ return true;
+ if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
+ test_bit(NVME_NS_REMOVING, &ns->flags))
+ return true;
+ return false;
}

static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
@@ -575,6 +584,9 @@ static void nvme_ana_work(struct work_struct *work)
{
struct nvme_ctrl *ctrl = container_of(work, struct nvme_ctrl, ana_work);

+ if (ctrl->state != NVME_CTRL_LIVE)
+ return;
+
nvme_read_ana_log(ctrl);
}

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 8f1b0a30fd2a6..ff0b4079e8d6d 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -183,6 +183,7 @@ enum nvme_ctrl_state {
NVME_CTRL_RESETTING,
NVME_CTRL_CONNECTING,
NVME_CTRL_DELETING,
+ NVME_CTRL_DELETING_NOIO,
NVME_CTRL_DEAD,
};

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 19c94080512cf..fdab0054cd809 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -1023,11 +1023,12 @@ static int nvme_rdma_setup_ctrl(struct nvme_rdma_ctrl *ctrl, bool new)
changed = nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_LIVE);
if (!changed) {
/*
- * state change failure is ok if we're in DELETING state,
+ * state change failure is ok if we started ctrl delete,
* unless we're during creation of a new controller to
* avoid races with teardown flow.
*/
- WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING);
+ WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING &&
+ ctrl->ctrl.state != NVME_CTRL_DELETING_NOIO);
WARN_ON_ONCE(new);
ret = -EINVAL;
goto destroy_io;
@@ -1080,8 +1081,9 @@ static void nvme_rdma_error_recovery_work(struct work_struct *work)
blk_mq_unquiesce_queue(ctrl->ctrl.admin_q);

if (!nvme_change_ctrl_state(&ctrl->ctrl, NVME_CTRL_CONNECTING)) {
- /* state change failure is ok if we're in DELETING state */
- WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING);
+ /* state change failure is ok if we started ctrl delete */
+ WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING &&
+ ctrl->ctrl.state != NVME_CTRL_DELETING_NOIO);
return;
}

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 99eaa0474e10b..06d6c1c6de35b 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1938,11 +1938,12 @@ static int nvme_tcp_setup_ctrl(struct nvme_ctrl *ctrl, bool new)

if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE)) {
/*
- * state change failure is ok if we're in DELETING state,
+ * state change failure is ok if we started ctrl delete,
* unless we're during creation of a new controller to
* avoid races with teardown flow.
*/
- WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
+ WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING &&
+ ctrl->state != NVME_CTRL_DELETING_NOIO);
WARN_ON_ONCE(new);
ret = -EINVAL;
goto destroy_io;
@@ -1998,8 +1999,9 @@ static void nvme_tcp_error_recovery_work(struct work_struct *work)
blk_mq_unquiesce_queue(ctrl->admin_q);

if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING)) {
- /* state change failure is ok if we're in DELETING state */
- WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
+ /* state change failure is ok if we started ctrl delete */
+ WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING &&
+ ctrl->state != NVME_CTRL_DELETING_NOIO);
return;
}

@@ -2034,8 +2036,9 @@ static void nvme_reset_ctrl_work(struct work_struct *work)
nvme_tcp_teardown_ctrl(ctrl, false);

if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_CONNECTING)) {
- /* state change failure is ok if we're in DELETING state */
- WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING);
+ /* state change failure is ok if we started ctrl delete */
+ WARN_ON_ONCE(ctrl->state != NVME_CTRL_DELETING &&
+ ctrl->state != NVME_CTRL_DELETING_NOIO);
return;
}

--
2.25.1