* Frederic Weisbecker <fweis...@gmail.com> wrote:
> On Tue, Aug 13, 2013 at 04:57:30PM +0200, Ingo Molnar wrote:
> >
> > * Frederic Weisbecker <fweis...@gmail.com> wrote:
> >
> > > > > 19 files changed, 534 insertions(+), 326 deletions(-)
> > > >
> > > > When merged to -tip it causes this build error:
> > > >
> > > > kernel/time/tick-sched.c:186:3: error: 'have_nohz_full_mask'
> > > > undeclared (first use in this function)
> > > > kernel/time/tick-sched.c:345:2: error: 'cpu' undeclared (first use in
> > > > this function)
> > > >
> > > > config attached.
> > > >
> > > > I did what looked like to be an obvious conflict resolution to
> > > > tick-sched.c (attached), please double check that too.
> > > >
> > > > While at it, mind rebasing your changes to tip:timers/urgent, which has
> > > > a
> > > > few nohz fixes pending as well?
> > >
> > > Ok I did the rebase on top of tip:timers/urgent and handled the
> > > conflicts along. The new branch is "timers/nohz-v2".
> > >
> > > Tell me if anything goes wrong with it.
> >
> > it produces this splat on bootup with the attached config, on a dual-core
> > Athlon64 box:
> >
> > calling context_tracking_init+0x0/0x3a @ 1
> > initcall context_tracking_init+0x0/0x3a returned 0 after 0 usecs
> > calling dynamic_debug_init+0x0/0x239 @ 1
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 1 at kernel/sched/cputime.c:639
> > get_vtime_delta+0x49/0x5f()
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.11.0-rc5-01689-g7830cba-dirty
> > #226899
> > Hardware name: System manufacturer System Product Name/A8N-E, BIOS ASUS
> > A8N-E ACPI BIOS Revision 1008 08/22/2005
> > 0000000000000009 ffff88003fa03ea8 ffffffff81f83f30 0000000000000b63
> > 0000000000000000 ffff88003fa03ee8 ffffffff810996a4 0000000000000000
> > ffffffff810bcfb5 ffff88003e33a000 0000000015752a00 0000000000000000
> > Call Trace:
> > <IRQ> [<ffffffff81f83f30>] dump_stack+0x46/0x58
> > [<ffffffff810996a4>] warn_slowpath_common+0x72/0x8c
> > [<ffffffff810bcfb5>] ? get_vtime_delta+0x49/0x5f
> > [<ffffffff8109976c>] warn_slowpath_null+0x15/0x19
> > [<ffffffff810bcfb5>] get_vtime_delta+0x49/0x5f
> > [<ffffffff810bd213>] __vtime_account_system+0xf/0x37
> > [<ffffffff810bd426>] vtime_account_system+0x21/0x2e
> > [<ffffffff810bd5bf>] vtime_common_account_irq_enter+0x41/0x43
> > [<ffffffff8109ce4a>] irq_enter+0x65/0x7c
> > [<ffffffff810434e2>] smp_apic_timer_interrupt+0x23/0x40
> > [<ffffffff81f9435d>] apic_timer_interrupt+0x6d/0x80
> > <EOI> [<ffffffff810c42d5>] ? arch_local_irq_restore+0x12/0x19
> > [<ffffffff810c5acb>] vprintk_emit+0x3e2/0x40a
> > [<ffffffff81099995>] ? cpu_maps_update_begin+0x12/0x14
> > [<ffffffff832e9244>] ? ddebug_setup_query+0x4d/0x4d
> > [<ffffffff81f80ddd>] printk+0x5c/0x5e
> > [<ffffffff8135caff>] __dynamic_pr_debug+0x79/0x7b
> > [<ffffffff810c764d>] ? timekeeping_get_ns.constprop.10+0x12/0x38
> > [<ffffffff832db12b>] ? init_hw_breakpoint+0xf7/0xf7
> > [<ffffffff810c7bbb>] ? ktime_get+0x65/0x74
> > [<ffffffff832db12b>] ? init_hw_breakpoint+0xf7/0xf7
> > [<ffffffff832e9244>] ? ddebug_setup_query+0x4d/0x4d
> > [<ffffffff832c4d9d>] do_one_initcall+0x5b/0x12a
> > [<ffffffff832d09a5>] ? native_smp_prepare_cpus+0x300/0x341
> > [<ffffffff832c4ed6>] kernel_init_freeable+0x6a/0x195
> > [<ffffffff81f7c075>] ? rest_init+0xb9/0xb9
> > [<ffffffff81f7c07e>] kernel_init+0x9/0xd1
> > [<ffffffff81f9357c>] ret_from_fork+0x7c/0xb0
> > [<ffffffff81f7c075>] ? rest_init+0xb9/0xb9
> > ---[ end trace 268f4433da36e82f ]---
> > initcall dynamic_debug_init+0x0/0x239 returned 0 after 0 usecs
> >
> > Thanks,
> >
> > Ingo
>
> Sorry about that, I missed it. This is because context tracking
> initialization when CONFIG_CONTEXT_TRACKING_FORCE=y is done too late. As
> a result, the user init task can run with context tracking disabled when
> it is scheduled for the first time and then later run with context
> tracking enabled due to the late initialization. And this finally messes
> up the state of context tracking internal on CPU 0.
>
> Anyway I fixed this by moving the context tracking initialization
> earlier, before irqs are enabled and the user init task is created.
>
> Please check out the branch "timers/nohz-v3".
>
> Only commit "context_tracking: Ground setup for static key use" which is
> now 65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c has changed to integrate
> the fix.
>
> And following is the diff against the previous branch.
Pulled, thanks Frederic! Seems to be working better now.
Thanks,
Ingo
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