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    Subject[PATCH 5.11 084/329] powerpc/smp: Set numa node before updating mask
    Date
    From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

    [ Upstream commit 6980d13f0dd189846887bbbfa43793d9a41768d3 ]

    Geethika reported a trace when doing a dlpar CPU add.

    ------------[ cut here ]------------
    WARNING: CPU: 152 PID: 1134 at kernel/sched/topology.c:2057
    CPU: 152 PID: 1134 Comm: kworker/152:1 Not tainted 5.12.0-rc5-master #5
    Workqueue: events cpuset_hotplug_workfn
    NIP: c0000000001cfc14 LR: c0000000001cfc10 CTR: c0000000007e3420
    REGS: c0000034a08eb260 TRAP: 0700 Not tainted (5.12.0-rc5-master+)
    MSR: 8000000000029033 <SF,EE,ME,IR,DR,RI,LE> CR: 28828422 XER: 00000020
    CFAR: c0000000001fd888 IRQMASK: 0 #012GPR00: c0000000001cfc10
    c0000034a08eb500 c000000001f35400 0000000000000027 #012GPR04:
    c0000035abaa8010 c0000035abb30a00 0000000000000027 c0000035abaa8018
    #012GPR08: 0000000000000023 c0000035abaaef48 00000035aa540000
    c0000035a49dffe8 #012GPR12: 0000000028828424 c0000035bf1a1c80
    0000000000000497 0000000000000004 #012GPR16: c00000000347a258
    0000000000000140 c00000000203d468 c000000001a1a490 #012GPR20:
    c000000001f9c160 c0000034adf70920 c0000034aec9fd20 0000000100087bd3
    #012GPR24: 0000000100087bd3 c0000035b3de09f8 0000000000000030
    c0000035b3de09f8 #012GPR28: 0000000000000028 c00000000347a280
    c0000034aefe0b00 c0000000010a2a68
    NIP [c0000000001cfc14] build_sched_domains+0x6a4/0x1500
    LR [c0000000001cfc10] build_sched_domains+0x6a0/0x1500
    Call Trace:
    [c0000034a08eb500] [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 (unreliable)
    [c0000034a08eb640] [c0000000001d1e6c] partition_sched_domains_locked+0x3ec/0x530
    [c0000034a08eb6e0] [c0000000002936d4] rebuild_sched_domains_locked+0x524/0xbf0
    [c0000034a08eb7e0] [c000000000296bb0] rebuild_sched_domains+0x40/0x70
    [c0000034a08eb810] [c000000000296e74] cpuset_hotplug_workfn+0x294/0xe20
    [c0000034a08ebc30] [c000000000178dd0] process_one_work+0x300/0x670
    [c0000034a08ebd10] [c0000000001791b8] worker_thread+0x78/0x520
    [c0000034a08ebda0] [c000000000185090] kthread+0x1a0/0x1b0
    [c0000034a08ebe10] [c00000000000ccec] ret_from_kernel_thread+0x5c/0x70
    Instruction dump:
    7d2903a6 4e800421 e8410018 7f67db78 7fe6fb78 7f45d378 7f84e378 7c681b78
    3c62ff1a 3863c6f8 4802dc35 60000000 <0fe00000> 3920fff4 f9210070 e86100a0
    ---[ end trace 532d9066d3d4d7ec ]---

    Some of the per-CPU masks use cpu_cpu_mask as a filter to limit the search
    for related CPUs. On a dlpar add of a CPU, update cpu_cpu_mask before
    updating the per-CPU masks. This will ensure the cpu_cpu_mask is updated
    correctly before its used in setting the masks. Setting the numa_node will
    ensure that when cpu_cpu_mask() gets called, the correct node number is
    used. This code movement helped fix the above call trace.

    Reported-by: Geetika Moolchandani <Geetika.Moolchandani1@ibm.com>
    Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Reviewed-by: Nathan Lynch <nathanl@linux.ibm.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20210401154200.150077-1-srikar@linux.vnet.ibm.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/kernel/smp.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
    index d1bc51a128b2..e285d55f9213 100644
    --- a/arch/powerpc/kernel/smp.c
    +++ b/arch/powerpc/kernel/smp.c
    @@ -1545,6 +1545,9 @@ void start_secondary(void *unused)

    vdso_getcpu_init();
    #endif
    + set_numa_node(numa_cpu_lookup_table[cpu]);
    + set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu]));
    +
    /* Update topology CPU masks */
    add_cpu_to_masks(cpu);

    @@ -1563,9 +1566,6 @@ void start_secondary(void *unused)
    shared_caches = true;
    }

    - set_numa_node(numa_cpu_lookup_table[cpu]);
    - set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu]));
    -
    smp_wmb();
    notify_cpu_starting(cpu);
    set_cpu_online(cpu, true);
    --
    2.30.2


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