Messages in this thread | | | Date | Wed, 10 Aug 2016 13:41:14 +0200 | From | Jiri Olsa <> | Subject | Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup |
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ping
thanks, jirka
On Wed, Aug 03, 2016 at 06:23:58PM +0200, Jiri Olsa wrote: > Frank reported kernel panic when he disabled several cores in BIOS > via following option: > > Core Disable Bitmap(Hex) [0] > > with number 0xFFE, which leaves 16 CPUs in system (out of 48). > > The kernel panic below goes along with following messages: > > smpboot: Max logical packages: 2^M > smpboot: APIC(0) Converting physical 0 to logical package 0^M > smpboot: APIC(20) Converting physical 1 to logical package 1^M > smpboot: APIC(40) Package 2 exceeds logical package map^M > smpboot: CPU 8 APICId 40 disabled^M > smpboot: APIC(60) Package 3 exceeds logical package map^M > smpboot: CPU 12 APICId 60 disabled^M > ... > general protection fault: 0000 [#1] SMP^M > Modules linked in:^M > CPU: 15 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc5+ #1^M > Hardware name: SGI UV300/UV300, BIOS SGI UV 300 series BIOS 05/25/2016^M > task: ffff8801673e0000 ti: ffff8801673ac000 task.ti: ffff8801673ac000^M > RIP: 0010:[<ffffffff81014d54>] [<ffffffff81014d54>] uncore_change_context+0xd4/0x180^M > ... > [<ffffffff810158ac>] uncore_event_init_cpu+0x6c/0x70^M > [<ffffffff81d8c91c>] intel_uncore_init+0x1c2/0x2dd^M > [<ffffffff81d8c75a>] ? uncore_cpu_setup+0x17/0x17^M > [<ffffffff81002190>] do_one_initcall+0x50/0x190^M > [<ffffffff810ab193>] ? parse_args+0x293/0x480^M > [<ffffffff81d87365>] kernel_init_freeable+0x1a5/0x249^M > [<ffffffff81d86a35>] ? set_debug_rodata+0x12/0x12^M > [<ffffffff816dc19e>] kernel_init+0xe/0x110^M > [<ffffffff816e93bf>] ret_from_fork+0x1f/0x40^M > [<ffffffff816dc190>] ? rest_init+0x80/0x80^M > > The reason for the panic is wrong value of __max_logical_packages, > which lets logical_package_map uninitialized and the uncore code > relying on this map being properly initialized (maybe we should > add some safety checks there as well). > > The __max_logical_packages is computed as: > > DIV_ROUND_UP(total_cpus, ncpus); > - ncpus being number of cores > > With above BIOS setup we get total_cpus == 16 which set > __max_logical_packages to 2 (ncpus is 12). > > Once topology_update_package_map processes CPU with logical > pkg over 2 we display above messages and fail to initialize > the physical_to_logical_pkg map, which makes the uncore code > crash. > > The fix is to set __max_logical_packages directly to total_cpus, > which should be the maximum possible logical ID of the pkg in > any case. > > Reported-by: Frank Ramsay <framsay@redhat.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 157bf0957219..484f7d357c77 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -340,7 +340,7 @@ static void __init smp_init_package_map(void) > ncpus = 1; > } > > - __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); > + __max_logical_packages = total_cpus; > > /* > * Possibly larger than what we need as the number of apic ids per
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