Fix backtrace in amd_e400_idle (rhbz 1031296)
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Josh Boyer
parent
1f3e7fdd87
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@ -626,6 +626,9 @@ Patch25189: ath9k-fix-bad-udelay.patch
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Patch25192: imx-hdmi-fix.patch
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Patch25192: imx-hdmi-fix.patch
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Patch25193: fix-exynos-hdmi-build.patch
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Patch25193: fix-exynos-hdmi-build.patch
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#rhbz 1031296
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Patch25194: tick-Clear-broadcast-pending-bit-when-switching-to-oneshot.patch
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# END OF PATCH DEFINITIONS
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# END OF PATCH DEFINITIONS
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%endif
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%endif
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@ -1274,6 +1277,9 @@ ApplyPatch ath9k-fix-bad-udelay.patch
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ApplyPatch imx-hdmi-fix.patch
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ApplyPatch imx-hdmi-fix.patch
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ApplyPatch fix-exynos-hdmi-build.patch
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ApplyPatch fix-exynos-hdmi-build.patch
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#rhbz 1031296
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ApplyPatch tick-Clear-broadcast-pending-bit-when-switching-to-oneshot.patch
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# END OF PATCH APPLICATIONS
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# END OF PATCH APPLICATIONS
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%endif
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%endif
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@ -2053,6 +2059,9 @@ fi
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# ||----w |
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# ||----w |
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# || ||
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# || ||
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%changelog
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%changelog
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* Wed Feb 12 2014 Josh Boyer <jwboyer@fedoraproject.org>
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- Fix backtrace in amd_e400_idle (rhbz 1031296)
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* Tue Feb 11 2014 Josh Boyer <jwboyer@fedoraproject.org> - 3.14.0-0.rc2.git1.1
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* Tue Feb 11 2014 Josh Boyer <jwboyer@fedoraproject.org> - 3.14.0-0.rc2.git1.1
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- Linux v3.14-rc2-26-g6792dfe
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- Linux v3.14-rc2-26-g6792dfe
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- Reenable debugging options.
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- Reenable debugging options.
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@ -0,0 +1,88 @@
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On Mon, 10 Feb 2014, Thomas Gleixner wrote:
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> On Mon, 10 Feb 2014, poma wrote:
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>
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> > [ 83.558551] [<ffffffff81025b17>] amd_e400_idle+0x87/0x130
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>
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> So this seems to happen only on AMD machines which use that e400 idle
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> mode. I have no idea at the moment whats wrong there. I'll find one of
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> those machines and try to reproduce.
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Found it. Patch below.
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Thanks,
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tglx
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----
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Subject: tick: Clear broadcast pending bit when switching to oneshot
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 11 Feb 2014 14:35:40 +0100
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AMD systems which use the C1E workaround in the amd_e400_idle routine
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trigger the WARN_ON_ONCE in the broadcast code when onlining a CPU.
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The reason is that the idle routine of those AMD systems switches the
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cpu into forced broadcast mode early on before the newly brought up
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CPU can switch over to high resolution / NOHZ mode. The timer related
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CPU1 bringup looks like this:
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clockevent_register_device(local_apic);
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tick_setup(local_apic);
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...
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idle()
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tick_broadcast_on_off(FORCE);
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tick_broadcast_oneshot_control(ENTER)
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cpumask_set(cpu, broadcast_oneshot_mask);
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halt();
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Now the broadcast interrupt on CPU0 sets CPU1 in the
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broadcast_pending_mask and wakes CPU1. So CPU1 continues:
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local_apic_timer_interrupt()
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tick_handle_periodic();
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softirq()
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tick_init_highres();
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cpumask_clr(cpu, broadcast_oneshot_mask);
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tick_broadcast_oneshot_control(ENTER)
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WARN_ON(cpumask_test(cpu, broadcast_pending_mask);
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So while we remove CPU1 from the broadcast_oneshot_mask when we switch
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over to highres mode, we do not clear the pending bit, which then
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triggers the warning when we go back to idle.
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The reason why this is only visible on C1E affected AMD systems is
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that the other machines enter the deep sleep states via
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acpi_idle/intel_idle and exit the broadcast mode before executing the
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remote triggered local_apic_timer_interrupt. So the pending bit is
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already cleared when the switch over to highres mode is clearing the
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oneshot mask.
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The solution is simple: Clear the pending bit together with the mask
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bit when we switch over to highres mode.
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Reported-by: poma <pomidorabelisima@gmail.com>
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Cc: stable@vger.kernel.org # 3.10+
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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kernel/time/tick-broadcast.c | 1 +
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1 file changed, 1 insertion(+)
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Index: linux-2.6/kernel/time/tick-broadcast.c
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===================================================================
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--- linux-2.6.orig/kernel/time/tick-broadcast.c
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+++ linux-2.6/kernel/time/tick-broadcast.c
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@@ -756,6 +756,7 @@ out:
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static void tick_broadcast_clear_oneshot(int cpu)
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{
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cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
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+ cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
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}
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static void tick_broadcast_init_next_event(struct cpumask *mask,
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