Endless soft-lockups for compiling workload since next-20200519

[Peter Zijlstra]

On Tue, May 19, 2020 at 11:58:17PM -0400, Qian Cai wrote:
> Just a head up. Repeatedly compiling kernels for a while would trigger
> endless soft-lockups since next-20200519 on both x86_64 and powerpc.
> .config are in,

Could be 90b5363acd47 ("sched: Clean up scheduler_ipi()"), although I've
not seen anything like that myself. Let me go have a look.


In as far as the logs are readable (they're a wrapped mess, please don't
do that!), they contain very little useful, as is typical with IPIs :/

> [ 1167.993773][    C1] WARNING: CPU: 1 PID: 0 at kernel/smp.c:127
> flush_smp_call_function_queue+0x1fa/0x2e0
> [ 1168.003333][    C1] Modules linked in: nls_iso8859_1 nls_cp437 vfat
> fat kvm_amd ses kvm enclosure dax_pmem irqbypass dax_pmem_core efivars
> acpi_cpufreq efivarfs ip_tables x_tables xfs sd_mod smartpqi
> scsi_transport_sas tg3 mlx5_core libphy firmware_class dm_mirror
> dm_region_hash dm_log dm_mod
> [ 1168.029492][    C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted
> 5.7.0-rc6-next-20200519 #1
> [ 1168.037665][    C1] Hardware name: HPE ProLiant DL385
> Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
> [ 1168.046978][    C1] RIP: 0010:flush_smp_call_function_queue+0x1fa/0x2e0
> [ 1168.053658][    C1] Code: 01 0f 87 c9 12 00 00 83 e3 01 0f 85 cc fe
> ff ff 48 c7 c7 c0 55 a9 8f c6 05 f6 86 cd 01 01 e8 de 09 ea ff 0f 0b
> e9 b2 fe ff ff <0f> 0b e9 52 ff ff ff 0f 0b e9 f2 fe ff ff 65 44 8b 25
> 10 52 3f 71
> [ 1168.073262][    C1] RSP: 0018:ffffc90000178918 EFLAGS: 00010046
> [ 1168.079253][    C1] RAX: 0000000000000000 RBX: ffff8888430c58f8
> RCX: ffffffff8ec26083
> [ 1168.087156][    C1] RDX: 0000000000000003 RSI: dffffc0000000000
> RDI: ffff8888430c58f8
> [ 1168.095054][    C1] RBP: ffffc900001789a8 R08: ffffed1108618cec
> R09: ffffed1108618cec
> [ 1168.102964][    C1] R10: ffff8888430c675b R11: 0000000000000000
> R12: ffff8888430c58e0
> [ 1168.110866][    C1] R13: ffffffff8eb30c40 R14: ffff8888430c5880
> R15: ffff8888430c58e0
> [ 1168.118767][    C1] FS:  0000000000000000(0000)
> GS:ffff888843080000(0000) knlGS:0000000000000000
> [ 1168.127628][    C1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 1168.134129][    C1] CR2: 000055b169604560 CR3: 0000000d08a14000
> CR4: 00000000003406e0
> [ 1168.142026][    C1] Call Trace:
> [ 1168.145206][    C1]  <IRQ>
> [ 1168.147957][    C1]  ? smp_call_on_cpu_callback+0xd0/0xd0
> [ 1168.153421][    C1]  ? rcu_read_lock_sched_held+0xac/0xe0
> [ 1168.158880][    C1]  ? rcu_read_lock_bh_held+0xc0/0xc0
> [ 1168.164076][    C1]  generic_smp_call_function_single_interrupt+0x13/0x2b
> [ 1168.170938][    C1]  smp_call_function_single_interrupt+0x157/0x4e0
> [ 1168.177278][    C1]  ? smp_call_function_interrupt+0x4e0/0x4e0
> [ 1168.183172][    C1]  ? interrupt_entry+0xe4/0xf0
> [ 1168.187846][    C1]  ? trace_hardirqs_off_caller+0x8d/0x1f0
> [ 1168.193478][    C1]  ? trace_hardirqs_on_caller+0x1f0/0x1f0
> [ 1168.199116][    C1]  ? _nohz_idle_balance+0x221/0x360
> [ 1168.204228][    C1]  ? trace_hardirqs_off_thunk+0x1a/0x1c
> [ 1168.209690][    C1]  call_function_single_interrupt+0xf/0x20