Messages in this thread | | | Date | Wed, 08 Aug 2012 00:33:49 +0800 | From | Jiang Liu <> | Subject | Re: [PATCH] x86/smp: Fix cpuN startup panic |
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On 08/07/2012 05:50 PM, Chen, LinX Z wrote: > From: Lin Chen <linx.z.chen@intel.com> > > We hit a panic while doing cpu hotplug test. > <0>[ 627.982857] Kernel panic - not syncing: smp_callin: CPU1 started up but did not get a callout! > <0>[ 627.982864] > <4>[ 627.982876] Pid: 0, comm: kworker/0:1 Tainted: G ... > <4>[ 627.982883] Call Trace: > <4>[ 627.982903] [<c18f2977>] panic+0x66/0x16c > <4>[ 627.982918] [<c12234cc>] ? default_get_apic_id+0x1c/0x40 > <4>[ 627.982931] [<c18ef96d>] start_secondary+0xda/0x252 > > During BSP bootup AP, it is possible that BSP be preempted before > finishing STARTUP sequence of AP(set cpu_callout_mask) which maybe cause > AP busy wait for it. At present, AP will wait for 2 seconds then panic. > > This patch let AP waits until BSP finish the startup sequence and gives > WARNING when BSP is preempted more than 2 seconds. > > Signed-off-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> > Signed-off-by: Lin Chen <linx.z.chen@intel.com> > --- > arch/x86/kernel/smpboot.c | 11 ++++++----- > 1 files changed, 6 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 7c5a8c3..a9e3379 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -165,19 +165,20 @@ static void __cpuinit smp_callin(void) > * Waiting 2s total for startup (udelay is not yet working) > */ > timeout = jiffies + 2*HZ; > - while (time_before(jiffies, timeout)) { > + while (1) { Hi Yanmin,
Seems a little risky, what if a slave CPU can't be booted due to hardware errors? Regards! Gerry
> /* > * Has the boot CPU finished it's STARTUP sequence? > */ > if (cpumask_test_cpu(cpuid, cpu_callout_mask)) > break; > cpu_relax(); > + if (!time_before(jiffies, timeout)) { > + WARN(1, "%s: CPU%d started up but did not get a callout!\n", > + __func__, cpuid); > + timeout = jiffies + 2*HZ; > + } > } > > - if (!time_before(jiffies, timeout)) { > - panic("%s: CPU%d started up but did not get a callout!\n", > - __func__, cpuid); > - } > > /* > * the boot CPU has finished the init stage and is spinning
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