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    SubjectRe: [Patch] x86 : set numa_nodes_parsed at acpi_numa_memory_affinity_init
    On 05/31/2012 07:25 PM, KOSAKI Motohiro wrote:
    > Hi Ishimatsu-san,
    >
    >
    > (5/29/12 3:45 AM), Yasuaki Ishimatsu wrote:
    >> When hot-adding a CPU into my system, the system showed following message
    >> since node_to_cpumask_map[2] was not allocated memory.
    >>
    >> Booting Node 2 Processor 32 APIC 0xc0
    >> node_to_cpumask_map[2] NULL
    >> Pid: 0, comm: swapper/32 Tainted: G A 3.3.5-acd #21
    >> Call Trace:
    >> [<ffffffff81048845>] debug_cpumask_set_cpu+0x155/0x160
    >> [<ffffffff8105e28a>] ? add_timer_on+0xaa/0x120
    >> [<ffffffff8150665f>] numa_add_cpu+0x1e/0x22
    >> [<ffffffff815020bb>] identify_cpu+0x1df/0x1e4
    >> [<ffffffff815020d6>] identify_econdary_cpu+0x16/0x1d
    >> [<ffffffff81504614>] smp_store_cpu_info+0x3c/0x3e
    >> [<ffffffff81505263>] smp_callin+0x139/0x1be
    >> [<ffffffff815052fb>] start_secondary+0x13/0xeb
    >>
    >> In my investigation, the root cause is that the bit of node 2 was not set at
    >> numa_nodes_parsed since hot-added cpu was not written in ACPI SRAT Table.
    >> But hot-added memory which is same PXM as the cpu is written in here.
    >
    > I don't understand this explanation. If cpu is not written in srat table,
    > it is firmware bug. isn't it? srat table should describe all possible cpus.
    > Why doesn't your system describe cpu info in acpi table?
    >
    >>
    >> ACPI Spec Rev 5.0 says about ACPI SRAT talbe as follows:
    >> This optional table provides information that allows OSPM to associate
    >> processors and memory ranges, including ranges of memory provided by
    >> hot-added memory devices, with system localities / proximity domains
    >> and clock domains.
    >>
    >> So I think the ACPI SRAT Table is not wrong. Thus numa_nodes_parsed should be set
    >> by not only acpi_numa_processor_affinity_init / acpi_numa_x2apic_affinity_init
    >> but also acpi_numa_memory_affinity_init for the case.
    >>
    >> Signed-off-by: Yasuaki Ishimatsu<isimatu.yasuaki@jp.fujitsu.com>
    >> ---
    >> arch/x86/mm/srat.c | 2 ++
    >> 1 file changed, 2 insertions(+)
    >>
    >> Index: linux-3.4/arch/x86/mm/srat.c
    >> ===================================================================
    >> --- linux-3.4.orig/arch/x86/mm/srat.c 2012-05-21 07:29:13.000000000 +0900
    >> +++ linux-3.4/arch/x86/mm/srat.c 2012-05-29 05:28:27.353916902 +0900
    >> @@ -176,6 +176,8 @@ acpi_numa_memory_affinity_init(struct ac
    >> return;
    >> }
    >>
    >> + node_set(node, numa_nodes_parsed);
    >> +
    >
    > But...
    > I think this patch itself is correct. If a system have cpuless memory node,
    > acpi_numa_processor_affinity_init / acpi_numa_x2apic_affinity_init can't
    > find any cpu description. but we need memory node allocation.
    SRAT table only provides information for CPUs present at boot time.
    For hot-added CPUs, the _PXM and _SLI methods provide the same information for them
    as SRAT table.

    >
    >
    >> printk(KERN_INFO "SRAT: Node %u PXM %u %Lx-%Lx\n", node, pxm,
    >> start, end);
    >> }
    >>
    >> --
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