On 6/3/19, Fangjian (Turing) <f.fangjian@xxxxxxxxxx> wrote: > Hi, We met a deadlock triggered by a NONFATAL AER event during a sysfs > "sriov_numvfs" operation. Any suggestion to fix such deadlock ? > > enable one VF > # echo 1 > /sys/devices/pci0000:74/0000:74:00.0/0000:75:00.0/sriov_numvfs > > The sysfs "sriov_numvfs" side is: > > sriov_numvfs_store > device_lock # hold the device_lock > ... > pci_enable_sriov > sriov_enable > ... > pci_device_add > down_write(&pci_bus_sem) # wait for > up_read(&pci_bus_sem) > > The AER side is: > > pcie_do_recovery > pci_walk_bus > down_read(&pci_bus_sem) # hold the rw_semaphore > report_resume Should we replace these device lock with try lock loop with some sleep statements. This could solve the immediate deadlock issues until someone implements granular locking in pci. > device_lock # wait for device_unlock() > > The calltrace is as below: > > [ 258.411464] INFO: task kworker/0:1:13 blocked for more than 120 seconds. > [ 258.418139] Tainted: G C O 5.1.0-rc1-ge2e3ca0 #1 > [ 258.424379] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables > this message. > [ 258.432172] kworker/0:1 D 0 13 2 0x00000028 > [ 258.437640] Workqueue: events aer_recover_work_func > [ 258.442496] Call trace: > [ 258.444933] __switch_to+0xb4/0x1b8 > [ 258.448409] __schedule+0x1ec/0x720 > [ 258.451884] schedule+0x38/0x90 > [ 258.455012] schedule_preempt_disabled+0x20/0x38 > [ 258.459610] __mutex_lock.isra.1+0x150/0x518 > [ 258.463861] __mutex_lock_slowpath+0x10/0x18 > [ 258.468112] mutex_lock+0x34/0x40 > [ 258.471413] report_resume+0x1c/0x78 > [ 258.474973] pci_walk_bus+0x58/0xb0 > [ 258.478451] pcie_do_recovery+0x18c/0x248 > [ 258.482445] aer_recover_work_func+0xe0/0x118 > [ 258.486783] process_one_work+0x1e4/0x468 > [ 258.490776] worker_thread+0x40/0x450 > [ 258.494424] kthread+0x128/0x130 > [ 258.497639] ret_from_fork+0x10/0x1c > [ 258.501329] INFO: task flr.sh:4534 blocked for more than 120 seconds. > [ 258.507742] Tainted: G C O 5.1.0-rc1-ge2e3ca0 #1 > [ 258.513980] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables > this message. > [ 258.521774] flr.sh D 0 4534 4504 0x00000000 > [ 258.527235] Call trace: > [ 258.529671] __switch_to+0xb4/0x1b8 > [ 258.533146] __schedule+0x1ec/0x720 > [ 258.536619] schedule+0x38/0x90 > [ 258.539749] rwsem_down_write_failed+0x14c/0x210 > [ 258.544347] down_write+0x48/0x60 > [ 258.547648] pci_device_add+0x1a0/0x290 > [ 258.551469] pci_iov_add_virtfn+0x190/0x358 > [ 258.555633] sriov_enable+0x24c/0x480 > [ 258.559279] pci_enable_sriov+0x14/0x28 > [ 258.563101] hisi_zip_sriov_configure+0x64/0x100 [hisi_zip] > [ 258.568649] sriov_numvfs_store+0xc4/0x190 > [ 258.572728] dev_attr_store+0x18/0x28 > [ 258.576375] sysfs_kf_write+0x3c/0x50 > [ 258.580024] kernfs_fop_write+0x114/0x1d8 > [ 258.584018] __vfs_write+0x18/0x38 > [ 258.587404] vfs_write+0xa4/0x1b0 > [ 258.590705] ksys_write+0x60/0xd8 > [ 258.594007] __arm64_sys_write+0x18/0x20 > [ 258.597914] el0_svc_common+0x5c/0x100 > [ 258.601646] el0_svc_handler+0x2c/0x80 > [ 258.605381] el0_svc+0x8/0xc > [ 379.243461] INFO: task kworker/0:1:13 blocked for more than 241 seconds. > [ 379.250134] Tainted: G C O 5.1.0-rc1-ge2e3ca0 #1 > [ 379.256373] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables > this message. > > > Thank you, > Jay > >
