From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Sinan Kaya <Okaya@kernel.org>,
"Fangjian (Turing)" <f.fangjian@huawei.com>
Cc: linux-pci@vger.kernel.org, Bjorn Helgaas <helgaas@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: Bug report: AER driver deadlock
Date: Wed, 05 Jun 2019 09:47:02 +1000 [thread overview]
Message-ID: <a1c90cfb9ce4062b4823c6647d7709baf1c5534f.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAK9iUCPREGruU7zGqnkS9w_x8Q7iE8twveEp2dn8ArupTTQyHA@mail.gmail.com>
On Tue, 2019-06-04 at 10:34 -0400, Sinan Kaya wrote:
> On 6/3/19, Fangjian (Turing) <f.fangjian@huawei.com> 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.
That won't necessarily solve this AB->BA problem. I think the issue
here is that sriov shouldn't device_lock before doing something that
can take the pci_bus_sem.
Ben.
> > 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
> >
> >
next prev parent reply other threads:[~2019-06-04 23:47 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-04 3:25 Bug report: AER driver deadlock Fangjian (Turing)
2019-06-04 14:34 ` Sinan Kaya
2019-06-04 23:47 ` Benjamin Herrenschmidt [this message]
2019-06-05 0:59 ` Sinan Kaya
2019-06-20 3:14 ` Fangjian (Turing)
2019-06-25 17:16 ` Bjorn Helgaas
2019-08-05 12:43 ` Fangjian (Turing)
2019-08-16 7:11 ` Jay Fang
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