Re: Possible deadlock related to CPU hotplug and kernfs

On Tuesday, September 08, 2015 12:40:08 PM Peter Zijlstra wrote: > On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote: > > On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > > Peter, Ingo, some help from lockdep expert is needed. > > > > We have a splat that almost

Re: Possible deadlock related to CPU hotplug and kernfs

On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote: > On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > Peter, Ingo, some help from lockdep expert is needed. > > We have a splat that almost certainly is a false positive (the original report > is here

Re: Possible deadlock related to CPU hotplug and kernfs

On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote: > On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > Peter, Ingo, some help from lockdep expert is needed. > > We have a splat that almost certainly is a false positive (the original report > is here

Re: Possible deadlock related to CPU hotplug and kernfs

On Tuesday, September 08, 2015 12:40:08 PM Peter Zijlstra wrote: > On Mon, Sep 07, 2015 at 11:33:21PM +0200, Rafael J. Wysocki wrote: > > On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > > Peter, Ingo, some help from lockdep expert is needed. > > > > We have a splat that almost

Re: Possible deadlock related to CPU hotplug and kernfs

On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > On 2015/9/4 22:16, Rafael J. Wysocki wrote: > > Hi, > > > > On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: > >> On 2015/9/4 4:08, Rafael J. Wysocki wrote: > >>> Hi Tejun, > >>> > >>> On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote:

Re: Possible deadlock related to CPU hotplug and kernfs

On Monday, September 07, 2015 11:11:19 AM Jiang Liu wrote: > On 2015/9/4 22:16, Rafael J. Wysocki wrote: > > Hi, > > > > On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: > >> On 2015/9/4 4:08, Rafael J. Wysocki wrote: > >>> Hi Tejun, > >>> > >>> On Thu, Sep 3, 2015 at

Re: Possible deadlock related to CPU hotplug and kernfs

On 2015/9/4 22:16, Rafael J. Wysocki wrote: > Hi, > > On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: >> On 2015/9/4 4:08, Rafael J. Wysocki wrote: >>> Hi Tejun, >>> >>> On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: Hello, Rafael. On Thu, Sep 03, 2015 at 02:58:16AM +0200,

Re: Possible deadlock related to CPU hotplug and kernfs

On 2015/9/4 22:16, Rafael J. Wysocki wrote: > Hi, > > On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: >> On 2015/9/4 4:08, Rafael J. Wysocki wrote: >>> Hi Tejun, >>> >>> On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: Hello, Rafael.

Re: Possible deadlock related to CPU hotplug and kernfs

Hi, On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: > On 2015/9/4 4:08, Rafael J. Wysocki wrote: >> Hi Tejun, >> >> On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: >>> Hello, Rafael. >>> >>> On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: So acpi_device_hotplug() calls

Re: Possible deadlock related to CPU hotplug and kernfs

On 2015/9/4 4:08, Rafael J. Wysocki wrote: > Hi Tejun, > > On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: >> Hello, Rafael. >> >> On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: >>> So acpi_device_hotplug() calls lock_device_hotplug() which simply >>> acquires

Re: Possible deadlock related to CPU hotplug and kernfs

Hi, On Fri, Sep 4, 2015 at 9:20 AM, Jiang Liu wrote: > On 2015/9/4 4:08, Rafael J. Wysocki wrote: >> Hi Tejun, >> >> On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: >>> Hello, Rafael. >>> >>> On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J.

Re: Possible deadlock related to CPU hotplug and kernfs

On 2015/9/4 4:08, Rafael J. Wysocki wrote: > Hi Tejun, > > On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: >> Hello, Rafael. >> >> On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: >>> So acpi_device_hotplug() calls lock_device_hotplug() which simply >>>

Re: Possible deadlock related to CPU hotplug and kernfs

Hi Tejun, On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: > Hello, Rafael. > > On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: >> So acpi_device_hotplug() calls lock_device_hotplug() which simply >> acquires device_hotplug_lock. It is held throughout the entire >>

Re: Possible deadlock related to CPU hotplug and kernfs

Hello, Rafael. On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: > So acpi_device_hotplug() calls lock_device_hotplug() which simply > acquires device_hotplug_lock. It is held throughout the entire > hot-add/hot-remove code path. > > Witing anything to

Re: Possible deadlock related to CPU hotplug and kernfs

Hello, Rafael. On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: > So acpi_device_hotplug() calls lock_device_hotplug() which simply > acquires device_hotplug_lock. It is held throughout the entire > hot-add/hot-remove code path. > > Witing anything to

Re: Possible deadlock related to CPU hotplug and kernfs

Hi Tejun, On Thu, Sep 3, 2015 at 6:19 PM, Tejun Heo wrote: > Hello, Rafael. > > On Thu, Sep 03, 2015 at 02:58:16AM +0200, Rafael J. Wysocki wrote: >> So acpi_device_hotplug() calls lock_device_hotplug() which simply >> acquires device_hotplug_lock. It is held throughout the

Re: Possible deadlock related to CPU hotplug and kernfs

On Wednesday, September 02, 2015 12:14:45 PM Tejun Heo wrote: > On Tue, Sep 01, 2015 at 03:12:34PM +0800, Jiang Liu wrote: > > Hi Rafael and Tejun, > > When running CPU hotplug tests, it triggers an lockdep warning > > as follow. The two possible deadlock paths are: > > 1) echo x >

Re: Possible deadlock related to CPU hotplug and kernfs

On Tue, Sep 01, 2015 at 03:12:34PM +0800, Jiang Liu wrote: > Hi Rafael and Tejun, > When running CPU hotplug tests, it triggers an lockdep warning > as follow. The two possible deadlock paths are: > 1) echo x > /sys/devices/system/cpu/cpux/online >->kernfs_fop_write() >

Re: Possible deadlock related to CPU hotplug and kernfs

On Tue, Sep 01, 2015 at 03:12:34PM +0800, Jiang Liu wrote: > Hi Rafael and Tejun, > When running CPU hotplug tests, it triggers an lockdep warning > as follow. The two possible deadlock paths are: > 1) echo x > /sys/devices/system/cpu/cpux/online >->kernfs_fop_write() >

Re: Possible deadlock related to CPU hotplug and kernfs

On Wednesday, September 02, 2015 12:14:45 PM Tejun Heo wrote: > On Tue, Sep 01, 2015 at 03:12:34PM +0800, Jiang Liu wrote: > > Hi Rafael and Tejun, > > When running CPU hotplug tests, it triggers an lockdep warning > > as follow. The two possible deadlock paths are: > > 1) echo x >