Re: Was: Re: [GIT PULL] timer changes for v3.6, Is: Regression introducedby 1e75fa8be9fb61e1af46b5b3b176347a4c958ca1

From: John Stultz
Date: Mon Jul 23 2012 - 13:47:33 EST


On 07/23/2012 07:49 AM, Konrad Rzeszutek Wilk wrote:
I hadn't looked in details of the patch, but this commit:

commit 1e75fa8be9fb61e1af46b5b3b176347a4c958ca1
Author: John Stultz <john.stultz@xxxxxxxxxx>
Date: Fri Jul 13 01:21:53 2012 -0400

time: Condense timekeeper.xtime into xtime_sec

causes 32-bit (and only 32-bit) bootup time crashes on Xen guests. I couldn't
do a git revert on top of Linus's tree (had a bunch of conflicts), but with
git bisection it narrowed down to that patch.

I could also bootup with git commit 55acdddbac1725b80df0c41970505e8a41c84956
(the smp-hotplug-for-linus merge), but with git commit
3992c0321258bdff3666cbaf5225f538ad61a548 (timers-core-for-linus merge aka this pull)
it went belly up.

This is the guest config:

extra="console=hvc0 debug earlyprintk=xen memblock=debug"
kernel="/mnt/lab/bootstrap-i386/vmlinuz"
ramdisk="/mnt/lab/bootstrap-i386/initramfs.cpio.gz"
mem=10248
vcpus=1
name="bootstrap-i386"
on_crash="preserve"

Attached is the crash log and I am also attaching the .config file and bisect log.

John, any thoughts? Is Xen clock timer (arch/x86/xen/time.c) code missing something obvious?

Thanks for the testing and the report! I'll take a closer look here and see.

Using config file "/test.xm".
Started domain bootstrap-i386 (id=4)
[ 0.000000] console [hvc0] enabled, bootconsole disabled
[ 0.000000] Xen: using vcpuop timer interface
[ 0.000000] installing Xen timer for CPU 0
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] WARNING: at /home/konrad/linux/kernel/time/clockevents.c:209 clockevents_program_event+0x176/0x190()
[ 0.000000] Modules linked in:
[ 0.000000] Pid: 0, comm: swapper/0 Not tainted 3.5.0upstream-00242-g3992c03 #1
[ 0.000000] Call Trace:
[ 0.000000] [<c1067aed>] warn_slowpath_common+0x6d/0xa0
[ 0.000000] [<c10aa846>] ? clockevents_program_event+0x176/0x190
[ 0.000000] [<c10aa846>] ? clockevents_program_event+0x176/0x190
[ 0.000000] [<c1067b3d>] warn_slowpath_null+0x1d/0x20
[ 0.000000] [<c10aa846>] clockevents_program_event+0x176/0x190
[ 0.000000] [<c10aaa36>] tick_setup_periodic+0x66/0xa0
[ 0.000000] [<c10aade7>] tick_notify+0x377/0x3d0
[ 0.000000] [<c1511043>] notifier_call_chain+0x43/0x60
[ 0.000000] [<c108985a>] raw_notifier_call_chain+0x1a/0x20
[ 0.000000] [<c10aa1f8>] clockevents_register_device+0x88/0xf0
[ 0.000000] [<c102fb12>] xen_setup_cpu_clockevents+0x22/0x40
[ 0.000000] [<c16bba3a>] xen_time_init+0xb7/0xbf
[ 0.000000] [<c16bcf1c>] x86_late_time_init+0x9/0x10
[ 0.000000] [<c16b7a7f>] start_kernel+0x286/0x317
[ 0.000000] [<c16b766a>] ? kernel_init+0x1cd/0x1cd
[ 0.000000] [<c16b72e6>] i386_start_kernel+0xa9/0xb0
[ 0.000000] [<c16ba609>] xen_start_kernel+0x5c9/0x5d1

Is this WARN_ON new, as well as the oops?

thanks
-john


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