From: Anton Eidelman anton@lightbitslabs.com
[ Upstream commit d8a22f85609fadb46ba699e0136cc3ebdeebff79 ]
In the following scenario scan_work and ana_work will deadlock:
When scan_work calls nvme_mpath_add_disk() this holds ana_lock and invokes nvme_parse_ana_log(), which may issue IO in device_add_disk() and hang waiting for an accessible path.
While nvme_mpath_set_live() only called when nvme_state_is_live(), a transition may cause NVME_SC_ANA_TRANSITION and requeue the IO.
Since nvme_mpath_set_live() holds ns->head->lock, an ana_work on ANY ctrl will not be able to complete nvme_mpath_set_live() on the same ns->head, which is required in order to update the new accessible path and remove NVME_NS_ANA_PENDING.. Therefore IO never completes: deadlock [1].
Fix: Move device_add_disk out of the head->lock and protect it with an atomic test_and_set for a new NVME_NS_HEAD_HAS_DISK bit.
[1]: kernel: INFO: task kworker/u8:2:160 blocked for more than 120 seconds. kernel: Tainted: G OE 5.3.5-050305-generic #201910071830 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: kworker/u8:2 D 0 160 2 0x80004000 kernel: Workqueue: nvme-wq nvme_ana_work [nvme_core] kernel: Call Trace: kernel: __schedule+0x2b9/0x6c0 kernel: schedule+0x42/0xb0 kernel: schedule_preempt_disabled+0xe/0x10 kernel: __mutex_lock.isra.0+0x182/0x4f0 kernel: __mutex_lock_slowpath+0x13/0x20 kernel: mutex_lock+0x2e/0x40 kernel: nvme_update_ns_ana_state+0x22/0x60 [nvme_core] kernel: nvme_update_ana_state+0xca/0xe0 [nvme_core] kernel: nvme_parse_ana_log+0xa1/0x180 [nvme_core] kernel: nvme_read_ana_log+0x76/0x100 [nvme_core] kernel: nvme_ana_work+0x15/0x20 [nvme_core] kernel: process_one_work+0x1db/0x380 kernel: worker_thread+0x4d/0x400 kernel: kthread+0x104/0x140 kernel: ret_from_fork+0x35/0x40 kernel: INFO: task kworker/u8:4:439 blocked for more than 120 seconds. kernel: Tainted: G OE 5.3.5-050305-generic #201910071830 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: kworker/u8:4 D 0 439 2 0x80004000 kernel: 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_mpath_add_disk+0xbe/0x100 [nvme_core] kernel: nvme_validate_ns+0x396/0x940 [nvme_core] kernel: nvme_scan_work+0x256/0x390 [nvme_core] kernel: process_one_work+0x1db/0x380 kernel: worker_thread+0x4d/0x400 kernel: kthread+0x104/0x140 kernel: ret_from_fork+0x35/0x40
Fixes: 0d0b660f214d ("nvme: add ANA support") Signed-off-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/multipath.c | 4 ++-- drivers/nvme/host/nvme.h | 2 ++ 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 18f0a05c74b56..574b52e911f08 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -417,11 +417,11 @@ static void nvme_mpath_set_live(struct nvme_ns *ns) if (!head->disk) return;
- mutex_lock(&head->lock); - if (!(head->disk->flags & GENHD_FL_UP)) + if (!test_and_set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) device_add_disk(&head->subsys->dev, head->disk, nvme_ns_id_attr_groups);
+ mutex_lock(&head->lock); if (nvme_path_is_optimized(ns)) { int node, srcu_idx;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 22e8401352c22..ed02260862cb5 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -345,6 +345,8 @@ struct nvme_ns_head { spinlock_t requeue_lock; struct work_struct requeue_work; struct mutex lock; + unsigned long flags; +#define NVME_NSHEAD_DISK_LIVE 0 struct nvme_ns __rcu *current_path[]; #endif };