lkml.org 
[lkml]   [2008]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: 2.6.25-mm1: not looking good

    * Andrew Morton <akpm@linux-foundation.org> wrote:

    > WARNING: at arch/x86/kernel/genapic_64.c:86 read_apic_id+0x31/0x67()
    >
    > [<ffffffff803523e6>] ? debug_smp_processor_id+0x32/0xc4
    > [<ffffffff8021ede5>] read_apic_id+0x31/0x67
    > [<ffffffff8066f7f2>] verify_local_APIC+0xa7/0x163
    > [<ffffffff8066e837>] native_smp_prepare_cpus+0x1ed/0x301
    > [<ffffffff80669ab2>] kernel_init+0x5a/0x276

    that came in via the UV-APIC patchset but the warning is entirely
    harmless. At that point we've got a single CPU running only so
    preemption of that code to another CPU is not possible.

    native_smp_prepare_cpus() should probably just disable preemption, that
    way we could remove all those ugly preempt disable-enable calls from the
    called functions - per the patch below. (not boot tested yet - might
    provoke atomic-scheduling warnings if i forgot about some schedule point
    in this rather large codepath)

    Ingo

    ------------------->
    Subject: x86: disable preemption in native_smp_prepare_cpus
    From: Ingo Molnar <mingo@elte.hu>
    Date: Fri Apr 18 11:07:10 CEST 2008

    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    arch/x86/kernel/smpboot.c | 2 ++
    1 file changed, 2 insertions(+)

    Index: linux-x86.q/arch/x86/kernel/smpboot.c
    ===================================================================
    --- linux-x86.q.orig/arch/x86/kernel/smpboot.c
    +++ linux-x86.q/arch/x86/kernel/smpboot.c
    @@ -1181,6 +1181,7 @@ static void __init smp_cpu_index_default
    */
    void __init native_smp_prepare_cpus(unsigned int max_cpus)
    {
    + preempt_disable();
    nmi_watchdog_default();
    smp_cpu_index_default();
    current_cpu_data = boot_cpu_data;
    @@ -1237,6 +1238,7 @@ void __init native_smp_prepare_cpus(unsi
    printk(KERN_INFO "CPU%d: ", 0);
    print_cpu_info(&cpu_data(0));
    setup_boot_clock();
    + preempt_enable();
    }
    /*
    * Early setup to make printk work.

    \
     
     \ /
      Last update: 2008-04-18 11:27    [W:0.023 / U:186.948 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site