Re: Possible regression with cgroups in 3.11

[Sasha Levin <sasha.levin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On 11/18/2013 03:39 PM, Bjorn Helgaas wrote:
> On Mon, Nov 18, 2013 at 11:29:32AM -0800, Yinghai Lu wrote:
>> On Mon, Nov 18, 2013 at 10:14 AM, Bjorn Helgaas <bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
>>>> A bit of comment here would be nice but yeah I think this should work.
>>>> Can you please also queue the revert of c2fda509667b ("workqueue:
>>>> allow work_on_cpu() to be called recursively") after this patch?
>>>> Please feel free to add my acked-by.
>>>
>>> OK, below are the two patches (Alex's fix + the revert) I propose to
>>> merge.  Unless there are objections, I'll ask Linus to pull these
>>> before v3.13-rc1.
>>>
>>>
>>>
>>> commit 84f23f99b507c2c9247f47d3db0f71a3fd65e3a3
>>> Author: Alexander Duyck <alexander.h.duyck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>>> Date:   Mon Nov 18 10:59:59 2013 -0700
>>>
>>>      PCI: Avoid unnecessary CPU switch when calling driver .probe() method
>>>
>>>      If we are already on a CPU local to the device, call the driver .probe()
>>>      method directly without using work_on_cpu().
>>>
>>>      This is a workaround for a lockdep warning in the following scenario:
>>>
>>>        pci_call_probe
>>>          work_on_cpu(cpu, local_pci_probe, ...)
>>>            driver .probe
>>>              pci_enable_sriov
>>>                ...
>>>                  pci_bus_add_device
>>>                    ...
>>>                      pci_call_probe
>>>                        work_on_cpu(cpu, local_pci_probe, ...)
>>>
>>>      It would be better to fix PCI so we don't call VF driver .probe() methods
>>>      from inside a PF driver .probe() method, but that's a bigger project.
>>>
>>>      [bhelgaas: disable preemption, open bugzilla, rework comments & changelog]
>>>      Link: https://bugzilla.kernel.org/show_bug.cgi?id=65071
>>>      Link: http://lkml.kernel.org/r/CAE9FiQXYQEAZ=0sG6+2OdffBqfLS9MpoN1xviRR9aDbxPxcKxQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org
>>>      Link: http://lkml.kernel.org/r/20130624195942.40795.27292.stgit-+uVpp3jiz/Q1YPczIWDRvLvm/XP+8Wra@public.gmane.org
>>>      Signed-off-by: Alexander Duyck <alexander.h.duyck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
>>>      Signed-off-by: Bjorn Helgaas <bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>>>      Acked-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>>
>> Tested-by: Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>> Acked-by: Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>
> Thanks, I added these and pushed my for-linus branch for -next to
> pick up before I ask Linus to pull them.

Hi guys,

This patch seems to be causing virtio (wouldn't it happen with any other driver too?) to give
the following spew:

[   11.966381] virtio-pci 0000:00:00.0: enabling device (0000 -> 0003)
[   11.968306] BUG: scheduling while atomic: swapper/0/1/0x00000002
[   11.968616] 2 locks held by swapper/0/1:
[   11.969144]  #0:  (&__lockdep_no_validate__){......}, at: [<ffffffff820162e8>] 
__driver_attach+0x48/0xa0
[   11.969720]  #1:  (&__lockdep_no_validate__){......}, at: [<ffffffff820162f9>] 
__driver_attach+0x59/0xa0
[   11.971519] Modules linked in:
[   11.971519] CPU: 3 PID: 1 Comm: swapper/0 Tainted: G        W 
3.12.0-next-20131120-sasha-00002-gf582b19 #4023
[   11.972293]  0000000000000003 ffff880fced736c8 ffffffff8429caa2 0000000000000003
[   11.973145]  ffff880fce820000 ffff880fced736e8 ffffffff8115b67b 0000000000000003
[   11.973952]  ffff880fe5dd7880 ffff880fced73768 ffffffff8429d463 ffff880fced73708
[   11.974881] Call Trace:
[   11.975233]  [<ffffffff8429caa2>] dump_stack+0x52/0x7f
[   11.975786]  [<ffffffff8115b67b>] __schedule_bug+0x6b/0x90
[   11.976411]  [<ffffffff8429d463>] __schedule+0x93/0x760
[   11.976971]  [<ffffffff810adfe4>] ? kvm_clock_read+0x24/0x50
[   11.977646]  [<ffffffff8429dde5>] schedule+0x65/0x70
[   11.978223]  [<ffffffff8429cb8d>] schedule_timeout+0x3d/0x260
[   11.978821]  [<ffffffff8117c8ce>] ? put_lock_stats+0xe/0x30
[   11.979595]  [<ffffffff8429eea7>] ? wait_for_completion+0xb7/0x120
[   11.980324]  [<ffffffff8117fd2a>] ? __lock_release+0x1da/0x1f0
[   11.981554]  [<ffffffff8429eea7>] ? wait_for_completion+0xb7/0x120
[   11.981664]  [<ffffffff8429eeaf>] wait_for_completion+0xbf/0x120
[   11.982266]  [<ffffffff81163880>] ? try_to_wake_up+0x2a0/0x2a0
[   11.982891]  [<ffffffff811421a8>] call_usermodehelper_exec+0x198/0x240
[   11.983552]  [<ffffffff811758e8>] ? complete+0x28/0x60
[   11.984053]  [<ffffffff81142385>] call_usermodehelper+0x45/0x50
[   11.984660]  [<ffffffff81a51d64>] kobject_uevent_env+0x594/0x600
[   11.985254]  [<ffffffff81a51ddb>] kobject_uevent+0xb/0x10
[   11.985855]  [<ffffffff82013635>] device_add+0x2b5/0x4a0
[   11.986495]  [<ffffffff8201383e>] device_register+0x1e/0x30
[   11.987051]  [<ffffffff81c59837>] register_virtio_device+0x87/0xb0
[   11.987760]  [<ffffffff81ac36a3>] ? pci_set_master+0x23/0x30
[   11.988410]  [<ffffffff81c5c3f2>] virtio_pci_probe+0x162/0x1c0
[   11.989000]  [<ffffffff81ac725c>] local_pci_probe+0x4c/0xb0
[   11.989683]  [<ffffffff81ac7361>] pci_call_probe+0xa1/0xd0
[   11.990359]  [<ffffffff81ac7643>] pci_device_probe+0x63/0xa0
[   11.991829]  [<ffffffff82015ce3>] ? driver_sysfs_add+0x73/0xb0
[   11.991829]  [<ffffffff8201601f>] really_probe+0x11f/0x2f0
[   11.992234]  [<ffffffff82016273>] driver_probe_device+0x83/0xb0
[   11.992847]  [<ffffffff8201630e>] __driver_attach+0x6e/0xa0
[   11.993407]  [<ffffffff820162a0>] ? driver_probe_device+0xb0/0xb0
[   11.994020]  [<ffffffff820162a0>] ? driver_probe_device+0xb0/0xb0
[   11.994719]  [<ffffffff82014066>] bus_for_each_dev+0x66/0xc0
[   11.995272]  [<ffffffff82015c1e>] driver_attach+0x1e/0x20
[   11.995829]  [<ffffffff8201552e>] bus_add_driver+0x11e/0x240
[   11.996411]  [<ffffffff870d3600>] ? virtio_mmio_init+0x14/0x14
[   11.996996]  [<ffffffff82016958>] driver_register+0xa8/0xf0
[   11.997628]  [<ffffffff870d3600>] ? virtio_mmio_init+0x14/0x14
[   11.998196]  [<ffffffff81ac7774>] __pci_register_driver+0x64/0x70
[   11.998798]  [<ffffffff870d3619>] virtio_pci_driver_init+0x19/0x1b
[   11.999421]  [<ffffffff810020ca>] do_one_initcall+0xca/0x1d0
[   12.000109]  [<ffffffff8114cf0b>] ? parse_args+0x1cb/0x310
[   12.000666]  [<ffffffff87065d76>] ? kernel_init_freeable+0x339/0x339
[   12.001364]  [<ffffffff87065a1a>] do_basic_setup+0x9c/0xbf
[   12.001903]  [<ffffffff87065d76>] ? kernel_init_freeable+0x339/0x339
[   12.002542]  [<ffffffff8708e894>] ? sched_init_smp+0x13f/0x141
[   12.003202]  [<ffffffff87065cf3>] kernel_init_freeable+0x2b6/0x339
[   12.003815]  [<ffffffff84292d4e>] ? kernel_init+0xe/0x130
[   12.004475]  [<ffffffff84292d40>] ? rest_init+0xd0/0xd0
[   12.005011]  [<ffffffff84292d4e>] kernel_init+0xe/0x130
[   12.005541]  [<ffffffff842ac9fc>] ret_from_fork+0x7c/0xb0
[   12.006068]  [<ffffffff84292d40>] ? rest_init+0xd0/0xd0


Thanks,
Sasha