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[76.23.2.87]) by smtp.googlemail.com with ESMTPSA id o2sm12004006wrh.13.2021.09.18.14.57.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 18 Sep 2021 14:58:01 -0700 (PDT) From: Anton Eidelman X-Google-Original-From: Anton Eidelman To: linux-nvme@lists.infradead.org, hch@lst.de, kbusch@kernel.org, sagi@grimberg.me, axboe@fb.com Cc: Anton Eidelman Subject: [PATCH] nvme/mpath: fix hang when disk goes live over reconnect Date: Sat, 18 Sep 2021 15:57:29 -0600 Message-Id: <20210918215729.388968-1-anton@lightbitslabs.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210918_145804_580208_38648548 X-CRM114-Status: GOOD ( 17.95 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org nvme_mpath_init_identify() invoked from nvme_init_identify() fetches a fresh ANA log from the ctrl. This is essential to have an up to date path states for both existing namespaces and for those scan_work may discover once the ctrl is up. This happens in the following cases: 1) A new ctrl is being connected. 2) An existing ctrl is successfully reconnected. 3) An existing ctrl is being reset. While in (1) ctrl->namespaces is empty, (2 & 3) may have namespaces, and nvme_read_ana_log() may call nvme_update_ns_ana_state(). This result in a hang when the ANA state of an existing namespace changes and makes the disk live: nvme_mpath_set_live() issues IO to the namespace through the ctrl, which does NOT have IO queues yet. See sample hang below. Solution: - move nvme_read_ana_log() call from nvme_mpath_init_identify() into a separate function, nvme_mpath_update(). - call this function in nvme_start_ctrl() - here the ctrl is ready. Downside: in case nvme_read_ana_log() fails, we do not find this out in nvme_mpath_init_identify(). Alernative solution: nvme_get_log() in nvme_mpath_init_identify(), but don't parse. Then nvme_start_ctrl() can just queue_work(nvme_wq, &ctrl->ana_work), along with scan_work. The ctrl->ana_log_buf contents is valid for scan_work, and ana_work will re-fetch and parse it. Downside: fetching an ANA log from the ctrl twice. Sample failure: nvme nvme0: starting error recovery nvme nvme0: Reconnecting in 10 seconds... block nvme0n6: no usable path - requeuing I/O INFO: task kworker/u8:3:312 blocked for more than 122 seconds. Tainted: G E 5.14.5-1.el7.elrepo.x86_64 #1 Workqueue: nvme-wq nvme_tcp_reconnect_ctrl_work [nvme_tcp] Call Trace: __schedule+0x2a2/0x7e0 schedule+0x4e/0xb0 io_schedule+0x16/0x40 wait_on_page_bit_common+0x15c/0x3e0 do_read_cache_page+0x1e0/0x410 read_cache_page+0x12/0x20 read_part_sector+0x46/0x100 read_lba+0x121/0x240 efi_partition+0x1d2/0x6a0 bdev_disk_changed.part.0+0x1df/0x430 bdev_disk_changed+0x18/0x20 blkdev_get_whole+0x77/0xe0 blkdev_get_by_dev+0xd2/0x3a0 __device_add_disk+0x1ed/0x310 device_add_disk+0x13/0x20 nvme_mpath_set_live+0x138/0x1b0 [nvme_core] nvme_update_ns_ana_state+0x2b/0x30 [nvme_core] nvme_update_ana_state+0xca/0xe0 [nvme_core] nvme_parse_ana_log+0xac/0x170 [nvme_core] nvme_read_ana_log+0x7d/0xe0 [nvme_core] nvme_mpath_init_identify+0x105/0x150 [nvme_core] nvme_init_identify+0x2df/0x4d0 [nvme_core] nvme_init_ctrl_finish+0x8d/0x3b0 [nvme_core] nvme_tcp_setup_ctrl+0x337/0x390 [nvme_tcp] nvme_tcp_reconnect_ctrl_work+0x24/0x40 [nvme_tcp] process_one_work+0x1bd/0x360 worker_thread+0x50/0x3d0 Signed-off-by: Anton Eidelman --- drivers/nvme/host/core.c | 1 + drivers/nvme/host/multipath.c | 9 ++++++--- drivers/nvme/host/nvme.h | 4 ++++ 3 files changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 97f8211cf92c..884ca1f6f80b 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -4325,6 +4325,7 @@ void nvme_start_ctrl(struct nvme_ctrl *ctrl) nvme_enable_aen(ctrl); if (ctrl->queue_count > 1) { + nvme_mpath_update(ctrl); nvme_queue_scan(ctrl); nvme_start_queues(ctrl); } diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index e8ccdd398f78..8bd133f66636 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -850,9 +850,7 @@ int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) return -ENOMEM; } ctrl->ana_log_size = ana_log_size; - error = nvme_read_ana_log(ctrl); - if (error) - goto out_uninit; + return 0; out_uninit: @@ -860,6 +858,11 @@ int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) return error; } +void nvme_mpath_update(struct nvme_ctrl *ctrl) +{ + nvme_read_ana_log(ctrl); +} + void nvme_mpath_uninit(struct nvme_ctrl *ctrl) { kfree(ctrl->ana_log_buf); diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 9871c0c9374c..1560ea7adc6b 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -746,6 +746,7 @@ void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id); void nvme_mpath_remove_disk(struct nvme_ns_head *head); int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id); void nvme_mpath_init_ctrl(struct nvme_ctrl *ctrl); +void nvme_mpath_update(struct nvme_ctrl *ctrl); void nvme_mpath_uninit(struct nvme_ctrl *ctrl); void nvme_mpath_stop(struct nvme_ctrl *ctrl); bool nvme_mpath_clear_current_path(struct nvme_ns *ns); @@ -820,6 +821,9 @@ static inline int nvme_mpath_init_identify(struct nvme_ctrl *ctrl, "Please enable CONFIG_NVME_MULTIPATH for full support of multi-port devices.\n"); return 0; } +static void nvme_mpath_update(struct nvme_ctrl *ctrl) +{ +} static inline void nvme_mpath_uninit(struct nvme_ctrl *ctrl) { } -- 2.25.1 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme