Re: Commit 35ce7f29a breaks hibernation for XPS 13

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Mon, Oct 27, 2014 at 09:47:57AM -0400, Eric B Munson wrote:
> On Fri, 24 Oct 2014, Paul E. McKenney wrote:
> 
> > On Fri, Oct 24, 2014 at 02:40:28PM -0400, Eric B Munson wrote:
> > > On Fri, 24 Oct 2014, Paul E. McKenney wrote:
> > > 
> > > > On Fri, Oct 24, 2014 at 12:36:12PM -0400, Eric B Munson wrote:
> > > > > On Fri, 24 Oct 2014, Paul E. McKenney wrote:
> > > > > 
> > > > > > On Fri, Oct 24, 2014 at 12:08:15PM -0400, Eric B Munson wrote:
> > > > > > > Paul,
> > > > > > > 
> > > > > > > As of 3.18-rc1 I can no longer hibernate my Dell XPS-13.  Bisect points
> > > > > > > the finger at 35ce7f29a.  A revert of that commit confirms, I can once
> > > > > > > again hibernate my machine without it.
> > > > > > > 
> > > > > > > When the hibernation fails I see this in dmesg:
> > > > > > > [   37.953313] PM: Syncing filesystems ... done.
> > > > > > > [   37.963694] Freezing user space processes ... (elapsed 0.001 seconds) done.
> > > > > > > [   37.965297] PM: Marking nosave pages: [mem 0x00000000-0x00000fff]
> > > > > > > [   37.965299] PM: Marking nosave pages: [mem 0x00058000-0x00058fff]
> > > > > > > [   37.965301] PM: Marking nosave pages: [mem 0x0009d000-0x000fffff]
> > > > > > > [   37.965304] PM: Marking nosave pages: [mem 0xc496a000-0xc4b6bfff]
> > > > > > > [   37.965315] PM: Marking nosave pages: [mem 0xdadb7000-0xdcffefff]
> > > > > > > [   37.965479] PM: Marking nosave pages: [mem 0xdd000000-0xffffffff]
> > > > > > > [   37.966000] PM: Basic memory bitmaps created
> > > > > > > [   37.966046] PM: Preallocating image memory... done (allocated 181989 pages)
> > > > > > > [   38.141524] PM: Allocated 727956 kbytes in 0.17 seconds (4282.09 MB/s)
> > > > > > > [   38.141525] Freezing remaining freezable tasks ... 
> > > > > > > [   58.151863] Freezing of tasks failed after 20.004 seconds (0 tasks refusing to freeze, wq_busy=1):
> > > > > > > [   58.151894] 
> > > > > > > [   58.151896] Restarting kernel threads ... done.
> > > > > > > [   58.181915] PM: Basic memory bitmaps freed
> > > > > > > [   58.181917] Restarting tasks ... done.
> > > > > > > 
> > > > > > > 
> > > > > > > I am not sure what else I can provide that might be useful, but I did
> > > > > > > see the thread on net-dev about this same commit.  Please CC me on any
> > > > > > > fixes and I will be happy to test.
> > > > > > 
> > > > > > Thank you for the bug report!
> > > > > > 
> > > > > > Does the following patch help?
> > > > > > 
> > > > > > 							Thanx, Paul
> > > > > 
> > > > > Paul,
> > > > > 
> > > > > This patch does not help.  I see the same dmesg output and failure to
> > > > > hibernate.
> > > > 
> > > > Thank you for testing it.  Does the following (untested, might not even
> > > > build) patch help?  (Or feel free to wait until I have done some testing
> > > > on it.)
> > > > 
> > > > 							Thanx, Paul
> > > 
> > > Still didn't help.  If it helps, when I attempt to reboot after trying
> > > to hibernate I see a kworker thread hung and get the stack trace below
> > > from that thread.  I assume this is the same thread that is holding up
> > > the hibernate.
> > 
> > Yep, looks like something that some other people are running into as well.
> > 
> > If you turn off CONFIG_RCU_NOCB_CPU, do you still get the failure?
> 
> Disabling CONFIG_RCU_NOCB_CPU fixes the problem.  I am able to hibernate
> and resume successfully.

Very good!  Then the fix I am working on might actually be a fix.  ;-)

							Thanx, Paul