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Message-ID: <2100C70C0D4CA64E+20241127220437.65ae99dd@john-PC> Date: Wed, 27 Nov 2024 22:04:37 +0800 From: Qiang Ma <maqianga@...ontech.com> To: Ming Lei <ming.lei@...hat.com> Cc: James.Bottomley@...senpartnership.com, martin.petersen@...cle.com, axboe@...nel.dk, dwagner@...e.de, hare@...e.de, linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] scsi: Don't wait for completion of in-flight requests On Tue, 26 Nov 2024 22:15:02 +0800 Ming Lei <ming.lei@...hat.com> wrote: > On Tue, Nov 26, 2024 at 07:50:08PM +0800, Qiang Ma wrote: > > Problem: > > When the system disk uses the scsi disk bus, The main > > qemu command line includes: > > ... > > -device virtio-scsi-pci,id=scsi0 \ > > -device scsi-hd,scsi-id=1,drive=drive-virtio-disk > > -drive id=drive-virtio-disk,if=none,file=/home/kvm/test.qcow2 > > ... > > > > The dmesg log is as follows:: > > > > [ 50.304591][ T4382] sd 0:0:0:0: [sda] Synchronizing SCSI cache > > [ 50.377002][ T4382] kexec_core: Starting new kernel > > [ 50.669775][ T194] psci: CPU1 killed (polled 0 ms) > > [ 50.849665][ T194] psci: CPU2 killed (polled 0 ms) > > [ 51.109625][ T194] psci: CPU3 killed (polled 0 ms) > > [ 51.319594][ T194] psci: CPU4 killed (polled 0 ms) > > [ 51.489667][ T194] psci: CPU5 killed (polled 0 ms) > > [ 51.709582][ T194] psci: CPU6 killed (polled 0 ms) > > [ 51.949508][ T10] psci: CPU7 killed (polled 0 ms) > > [ 52.139499][ T10] psci: CPU8 killed (polled 0 ms) > > [ 52.289426][ T10] psci: CPU9 killed (polled 0 ms) > > [ 52.439552][ T10] psci: CPU10 killed (polled 0 ms) > > [ 52.579525][ T10] psci: CPU11 killed (polled 0 ms) > > [ 52.709501][ T10] psci: CPU12 killed (polled 0 ms) > > [ 52.819509][ T194] psci: CPU13 killed (polled 0 ms) > > [ 52.919509][ T194] psci: CPU14 killed (polled 0 ms) > > [ 243.214009][ T115] INFO: task kworker/0:1:10 blocked for more > > than 122 seconds. [ 243.214810][ T115] Not tainted 6.6.0+ #1 > > [ 243.215517][ T115] "echo 0 > > > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > [ 243.216390][ T115] task:kworker/0:1 state:D stack:0 > > > pid:10 ppid:2 flags:0x00000008 > > [ 243.217299][ T115] Workqueue: events vmstat_shepherd > > [ 243.217816][ T115] Call trace: > > [ 243.218133][ T115] __switch_to+0x130/0x1e8 > > [ 243.218568][ T115] __schedule+0x660/0xcf8 > > [ 243.219013][ T115] schedule+0x58/0xf0 > > [ 243.219402][ T115] percpu_rwsem_wait+0xb0/0x1d0 > > [ 243.219880][ T115] __percpu_down_read+0x40/0xe0 > > [ 243.220353][ T115] cpus_read_lock+0x5c/0x70 > > [ 243.220795][ T115] vmstat_shepherd+0x40/0x140 > > [ 243.221250][ T115] process_one_work+0x170/0x3c0 > > [ 243.221726][ T115] worker_thread+0x234/0x3b8 > > [ 243.222176][ T115] kthread+0xf0/0x108 > > [ 243.222564][ T115] ret_from_fork+0x10/0x20 > > ... > > [ 243.254080][ T115] INFO: task kworker/0:2:194 blocked for more > > than 122 seconds. [ 243.254834][ T115] Not tainted 6.6.0+ #1 > > [ 243.255529][ T115] "echo 0 > > > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > [ 243.256378][ T115] task:kworker/0:2 state:D stack:0 > > > pid:194 ppid:2 flags:0x00000008 > > [ 243.257284][ T115] Workqueue: events work_for_cpu_fn > > [ 243.257793][ T115] Call trace: > > [ 243.258111][ T115] __switch_to+0x130/0x1e8 > > [ 243.258541][ T115] __schedule+0x660/0xcf8 > > [ 243.258971][ T115] schedule+0x58/0xf0 > > [ 243.259360][ T115] schedule_timeout+0x280/0x2f0 > > [ 243.259832][ T115] wait_for_common+0xcc/0x2d8 > > [ 243.260287][ T115] wait_for_completion+0x20/0x38 > > [ 243.260767][ T115] cpuhp_kick_ap+0xe8/0x278 > > [ 243.261207][ T115] cpuhp_kick_ap_work+0x5c/0x188 > > [ 243.261688][ T115] _cpu_down+0x120/0x378 > > [ 243.262103][ T115] __cpu_down_maps_locked+0x20/0x38 > > [ 243.262609][ T115] work_for_cpu_fn+0x24/0x40 > > [ 243.263059][ T115] process_one_work+0x170/0x3c0 > > [ 243.263533][ T115] worker_thread+0x234/0x3b8 > > [ 243.263981][ T115] kthread+0xf0/0x108 > > [ 243.264405][ T115] ret_from_fork+0x10/0x20 > > [ 243.264846][ T115] INFO: task kworker/15:2:639 blocked for more > > than 122 seconds. [ 243.265602][ T115] Not tainted 6.6.0+ #1 > > [ 243.266296][ T115] "echo 0 > > > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > > [ 243.267143][ T115] task:kworker/15:2 state:D stack:0 > > > pid:639 ppid:2 flags:0x00000008 > > [ 243.268044][ T115] Workqueue: events_freezable_power_ > > disk_events_workfn [ 243.268727][ T115] Call trace: > > [ 243.269051][ T115] __switch_to+0x130/0x1e8 > > [ 243.269481][ T115] __schedule+0x660/0xcf8 > > [ 243.269903][ T115] schedule+0x58/0xf0 > > [ 243.270293][ T115] schedule_timeout+0x280/0x2f0 > > [ 243.270763][ T115] io_schedule_timeout+0x50/0x70 > > [ 243.271245][ T115] wait_for_common_io.constprop.0+0xb0/0x298 > > [ 243.271830][ T115] wait_for_completion_io+0x1c/0x30 > > [ 243.272335][ T115] blk_execute_rq+0x1d8/0x278 > > [ 243.272793][ T115] scsi_execute_cmd+0x114/0x238 > > [ 243.273267][ T115] sr_check_events+0xc8/0x310 [sr_mod] > > [ 243.273808][ T115] cdrom_check_events+0x2c/0x50 [cdrom] > > [ 243.274408][ T115] sr_block_check_events+0x34/0x48 [sr_mod] > > [ 243.274994][ T115] disk_check_events+0x44/0x1b0 > > [ 243.275468][ T115] disk_events_workfn+0x20/0x38 > > [ 243.275939][ T115] process_one_work+0x170/0x3c0 > > [ 243.276410][ T115] worker_thread+0x234/0x3b8 > > [ 243.276855][ T115] kthread+0xf0/0x108 > > [ 243.277241][ T115] ret_from_fork+0x10/0x20 > > Question is why this scsi command can't be completed? > > When blk_mq_hctx_notify_offline() is called, the CPU isn't shutdown > yet, and it still can handle interrupt of this SCSI command. > > > Thanks, > Ming > > Sorry, at the moment I don't know why it can't be finished, just provides a solution like loop and dm-rq. Currently see the call stack: => blk_mq_run_hw_queue =>__blk_mq_sched_restart => blk_mq_run_hw_queue => __blk_mq_sched_restart => __blk_mq_free_request => blk_mq_free_request => blk_mq_end_request => blk_flush_complete_seq => flush_end_io => __blk_mq_end_request => scsi_end_request => scsi_io_completion => scsi_finish_command => scsi_complete => blk_mq_complete_request => scsi_done_internal => scsi_done => virtscsi_complete_cmd => virtscsi_req_done => vring_interrupt In finction blk_mq_run_hw_queue(): __blk_mq_run_dispatch_ops(hctx->queue, false, need_run = !blk_queue_quiesced(hctx->queue) && blk_mq_hctx_has_pending(hctx)); if (!need_run) return; Come here and return directly.
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