Re: Linux 3.7-rc3

[Hugo Mills <hugo-lkml@carfax.org.uk>]

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On Tue, Oct 30, 2012 at 01:10:32AM +0100, Rafael J. Wysocki wrote:
> On Sunday, October 28, 2012 12:59:49 PM Linus Torvalds wrote:
> > It's been a week, time for -rc3!
> > 
> > Nothing particularly stands out here. Lots of small fixes, exemplified
> > by the series of memory leak fixes in usb serial drivers. Just a lot
> > of random stuff..
> > 
> > Most of it is drivers (all over: drm, wireless, staging, usb, sound),
> > but there's a few filesystem updates (nfs, btrfs, ext4), arch updates
> > (arm, x86 and m68k) and just random stuff. Shortlog appended.
> 
> Unfortunately, s2disk is broken with this one and previous -rc.  In the
> majority of cases it just hangs the machine during hibernation, although
> sometimes it returns to user space reporting freezing problems, suspicions
> RCU usage and similar stuff, pretty much without any useful debug information.
> 
> I'm quite confident that v3.6 was OK (and -stable based on that too), so
> it most likely is a recent regression.  The in-kernel hibernation
> (ie. "echo disk > /sys/power/state") works no problem.  So does suspend to
> RAM on my test boxes.
> 
> So far I have been able to reproduce this 100% of the time on two machines
> with Intel CPUs and graphics driven by i915.  I _suspect_ that this may be
> related to VT switching, because s2disk does some ugly things in that area
> which are not done by the in-kernel code.  Dunno.

   I've had this symptom on my laptop (Thinkpad Edge 13, Intel
graphics & CPU; I can get details when I get back home in about 8
hours), but only with 3.7-rc2. It was definitely working in 3.6, and
seems to be OK in 3.7-rc3, although I've only tried two cycles of that
last night.

   When I did suspend to disk, I get a blank screen (but clearly with
backlight still on), and a blinking text-mode cursor in the top left.
I left it for half an hour once, and nothing changed, so I'm fairly
sure it was properly hung. I've not seen it return to user space with
errors at all -- just the hang.

> Anyway, it looks like nothing short of bisection is going to help debug this,
> but I'm afraid I won't have the time to bisect within the next two weeks, so if
> anyone can reproduce this issue and will be able to bisect it, please help
> (openSUSE/Tumbleweed users anyone?).

   I can try to bisect the 3.6 -> 3.7-rc2 failure, if that helps? But
as I said, I've got it working on -rc3, so I may not have the same
problem.

   Hugo.

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=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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