rcu_sched stall OR kernel panic on PowerEdge R640

george1421

@djgalloway Just for clarity

So the only difference between the kernel starting and not is the acpi=off being used?

Is this still accurate?

djgalloway

@george1421 Right. So, it turns out I had the wrong serial TTY set. I changed it to console=ttyS1,115200 without acpi=off and got the following:

Linux version 4.19.64 (jenkins-agent@Tollana) (gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1)) #1 SMP Mon Aug 5 11:08:49 CDT 2019
Command line: loglevel=7 initrd=init.xz root=/dev/ram0 rw ramdisk_size=127000 web=http://10.8.128.2/fog/ consoleblank=0 rootfstype=ext4 console=tty0 console=ttyS1,115200 mac=e4:43:4b:7d:a9:ba ftp=10.8.128.2 storage=10.8.128.2:/opt/fog/images/dev/ storageip=10.8.128.2 osi0
KERNEL supported cpus:
  Intel GenuineIntel
  AMD AuthenticAMD
  Centaur CentaurHauls
x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
x86/fpu: Supporting XSAVE feature 0x008: 'MPX bounds registers'
x86/fpu: Supporting XSAVE feature 0x010: 'MPX CSR'
x86/fpu: Supporting XSAVE feature 0x020: 'AVX-512 opmask'
x86/fpu: Supporting XSAVE feature 0x040: 'AVX-512 Hi256'
x86/fpu: Supporting XSAVE feature 0x080: 'AVX-512 ZMM_Hi256'
x86/fpu: Supporting XSAVE feature 0x200: 'Protection Keys User registers'
x86/fpu: xstate_offset[2]:  576, xstate_sizes[2]:  256
x86/fpu: xstate_offset[3]:  832, xstate_sizes[3]:   64
x86/fpu: xstate_offset[4]:  896, xstate_sizes[4]:   64
x86/fpu: xstate_offset[5]:  960, xstate_sizes[5]:   64
x86/fpu: xstate_offset[6]: 1024, xstate_sizes[6]:  512
x86/fpu: xstate_offset[7]: 1536, xstate_sizes[7]: 1024
x86/fpu: xstate_offset[9]: 2560, xstate_sizes[9]:    8
x86/fpu: Enabled xstate features 0x2ff, context size is 2568 bytes, using 'compacted' format.
BIOS-provided physical RAM map:
BIOS-e820: [mem 0x0000000000000000-0x000000000008bfff] usable
BIOS-e820: [mem 0x000000000008c000-0x000000000009ffff] reserved
BIOS-e820: [mem 0x00000000000e0000-0x00000000000fffff] reserved
BIOS-e820: [mem 0x0000000000100000-0x000000005ddfefff] usable
BIOS-e820: [mem 0x000000005ddff000-0x000000006cffefff] reserved
BIOS-e820: [mem 0x000000006cfff000-0x000000006effefff] ACPI NVS
BIOS-e820: [mem 0x000000006efff000-0x000000006f7fefff] ACPI data
BIOS-e820: [mem 0x000000006f7ff000-0x000000006f7fffff] usable
BIOS-e820: [mem 0x000000006f800000-0x000000008fffffff] reserved
BIOS-e820: [mem 0x00000000fd000000-0x00000000fe7fffff] reserved
BIOS-e820: [mem 0x00000000fec00000-0x00000000fec00fff] reserved
BIOS-e820: [mem 0x00000000fec80000-0x00000000fed00fff] reserved
BIOS-e820: [mem 0x00000000fed40000-0x00000000fed44fff] reserved
BIOS-e820: [mem 0x00000000ff000000-0x00000000ffffffff] reserved
BIOS-e820: [mem 0x0000000100000000-0x000000183fffffff] usable
NX (Execute Disable) protection: active
SMBIOS 3.2 present.
DMI: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.2.11 06/13/2019
tsc: Detected 2200.000 MHz processor
last_pfn = 0x1840000 max_arch_pfn = 0x400000000
x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WP  UC- WT  
x2apic: enabled by BIOS, switching to x2apic ops
last_pfn = 0x6f800 max_arch_pfn = 0x400000000
Using GB pages for direct mapping
RAMDISK: [mem 0x5ca97000-0x5dd50fff]
ACPI: Early table checksum verification disabled
ACPI: RSDP 0x00000000000FE320 000024 (v02 DELL  )
ACPI: XSDT 0x000000006F41B188 0000F4 (v01 DELL   PE_SC3   00000000      01000013)
ACPI: FACP 0x000000006F7F9000 000114 (v06 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: DSDT 0x000000006F507000 2E2494 (v02 DELL   PE_SC3   00000003 DELL 00000001)
ACPI: FACS 0x000000006EA6E000 000040
ACPI: SSDT 0x000000006F7FC000 00046C (v02 INTEL  ADDRXLAT 00000001 INTL 20180508)
ACPI: WDAT 0x000000006F7FB000 000134 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: SLIC 0x000000006F7FA000 000024 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: HPET 0x000000006F7F8000 000038 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: APIC 0x000000006F7F6000 0016DE (v04 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: MCFG 0x000000006F7F5000 00003C (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: MIGT 0x000000006F7F4000 000040 (v01 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: MSCT 0x000000006F7F3000 000090 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: PCAT 0x000000006F7F2000 000088 (v02 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: PCCT 0x000000006F7F1000 00006E (v01 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: RASF 0x000000006F7F0000 000030 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: SLIT 0x000000006F7EF000 00042C (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: SRAT 0x000000006F7EC000 002D30 (v03 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: SVOS 0x000000006F7EB000 000032 (v01 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: WSMT 0x000000006F7EA000 000028 (v01 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: OEM4 0x000000006F459000 0AD1C1 (v02 INTEL  CPU  CST 00003000 INTL 20180508)
ACPI: SSDT 0x000000006F421000 037465 (v02 INTEL  SSDT  PM 00004000 INTL 20180508)
ACPI: SSDT 0x000000006F407000 000A1F (v02 DELL   PE_SC3   00000000 DELL 00000001)
ACPI: SSDT 0x000000006F41D000 00357F (v02 INTEL  SpsNm    00000002 INTL 20180508)
ACPI: SPCR 0x000000006F41C000 000050 (v02                 00000000      00000000)
ACPI: DMAR 0x000000006F7FD000 000260 (v01 DELL   PE_SC3   00000001 DELL 00000001)
ACPI: HEST 0x000000006F3F6000 00017C (v01 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: BERT 0x000000006F3F5000 000030 (v01 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: ERST 0x000000006F3F4000 000230 (v01 DELL   PE_SC3   00000002 DELL 00000001)
ACPI: EINJ 0x000000006F3F3000 000150 (v01 DELL   PE_SC3   00000002 DELL 00000001)
Setting APIC routing to cluster x2apic.
Zone ranges:
  DMA      [mem 0x0000000000001000-0x0000000000ffffff]
  DMA32    [mem 0x0000000001000000-0x00000000ffffffff]
  Normal   [mem 0x0000000100000000-0x000000183fffffff]
Movable zone start for each node
Early memory node ranges
  node   0: [mem 0x0000000000001000-0x000000000008bfff]
  node   0: [mem 0x0000000000100000-0x000000005ddfefff]
  node   0: [mem 0x000000006f7ff000-0x000000006f7fffff]
  node   0: [mem 0x0000000100000000-0x000000183fffffff]
Reserved but unavailable: 117 pages
Initmem setup node 0 [mem 0x0000000000001000-0x000000183fffffff]
ACPI: PM-Timer IO Port: 0x508
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 8/0x4 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 9/0x24 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 10/0x18 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 11/0x38 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 12/0x10 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 13/0x30 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 14/0x16 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 15/0x36 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 16/0x12 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 17/0x32 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 18/0x14 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 19/0x34 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 20/0x1 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 21/0x21 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 22/0x9 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 23/0x29 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 24/0x3 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 25/0x23 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 26/0x7 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 27/0x27 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 28/0x5 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 29/0x25 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 30/0x19 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 31/0x39 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 32/0x11 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 33/0x31 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 34/0x17 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 35/0x37 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 36/0x13 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 37/0x33 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 38/0x15 ignored.
APIC: NR_CPUS/possible_cpus limit of 8 reached. Processor 39/0x35 ignored.
ACPI: X2APIC_NMI (uid[0xffffffff] high level lint[0x1])
ACPI: LAPIC_NMI (acpi_id[0xff] high level lint[0x1])
IOAPIC[0]: apic_id 8, version 32, address 0xfec00000, GSI 0-23
IOAPIC[1]: apic_id 9, version 32, address 0xfec01000, GSI 24-31
IOAPIC[2]: apic_id 10, version 32, address 0xfec08000, GSI 32-39
IOAPIC[3]: apic_id 11, version 32, address 0xfec10000, GSI 40-47
IOAPIC[4]: apic_id 12, version 32, address 0xfec18000, GSI 48-55
IOAPIC[5]: apic_id 15, version 32, address 0xfec20000, GSI 72-79
IOAPIC[6]: apic_id 16, version 32, address 0xfec28000, GSI 80-87
IOAPIC[7]: apic_id 17, version 32, address 0xfec30000, GSI 88-95
IOAPIC[8]: apic_id 18, version 32, address 0xfec38000, GSI 96-103
ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
Using ACPI (MADT) for SMP configuration information
ACPI: HPET id: 0x8086a701 base: 0xfed00000
ACPI: SPCR: console: uart,io,0x2f8,115200
smpboot: 40 Processors exceeds NR_CPUS limit of 8
smpboot: Allowing 8 CPUs, 0 hotplug CPUs
[mem 0x90000000-0xfcffffff] available for PCI devices
Booting paravirtualized kernel on bare hardware
clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns
random: get_random_bytes called from 0xffffffff82cafa32 with crng_init=0
setup_percpu: NR_CPUS:8 nr_cpumask_bits:8 nr_cpu_ids:8 nr_node_ids:1
percpu: Embedded 41 pages/cpu s130840 r8192 d28904 u262144
Built 1 zonelists, mobility grouping on.  Total pages: 24376830
Kernel command line: loglevel=7 initrd=init.xz root=/dev/ram0 rw ramdisk_size=127000 web=http://10.8.128.2/fog/ consoleblank=0 rootfstype=ext4 console=tty0 console=ttyS1,115200 mac=e4:43:4b:7d:a9:ba ftp=10.8.128.2 storage=10.8.128.2:/opt/fog/images/dev/ storageip=10.8.120
Misrouted IRQ fixup and polling support enabled
This may significantly impact system performance
Dentry cache hash table entries: 8388608 (order: 14, 67108864 bytes)
Inode-cache hash table entries: 4194304 (order: 13, 33554432 bytes)
Memory: 97287048K/99055148K available (16392K kernel code, 992K rwdata, 4548K rodata, 1056K init, 2416K bss, 1768100K reserved, 0K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1
Kernel/User page tables isolation: enabled
rcu: Hierarchical RCU implementation.
NR_IRQS: 4352, nr_irqs: 1848, preallocated irqs: 16
Console: colour VGA+ 80x25
console [tty0] enabled
console [ttyS1] enabled
ACPI: Core revision 20180810
clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635855245 ns
APIC: Switch to symmetric I/O mode setup
x2apic: IRQ remapping doesn't support X2APIC mode
x2apic disabled
Switched APIC routing to flat.
..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x1fb633008a4, max_idle_ns: 440795292230 ns
Calibrating delay loop (skipped), value calculated using timer frequency.. 4400.00 BogoMIPS (lpj=2200000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Mountpoint-cache hash table entries: 131072 (order: 8, 1048576 bytes)
ENERGY_PERF_BIAS: Set to 'normal', was 'performance'
ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)
process: using mwait in idle threads
Last level iTLB entries: 4KB 64, 2MB 8, 4MB 8
Last level dTLB entries: 4KB 64, 2MB 0, 4MB 0, 1GB 4
Spectre V2 : Mitigation: Full generic retpoline
Spectre V2 : Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch
Spectre V2 : Enabling Restricted Speculation for firmware calls
Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier
Spectre V2 : User space: Mitigation: STIBP via seccomp and prctl
Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl and seccomp
MDS: Mitigation: Clear CPU buffers
Freeing SMP alternatives memory: 52K
smpboot: CPU0: Intel(R) Xeon(R) Silver 4114 CPU @ 2.20GHz (family: 0x6, model: 0x55, stepping: 0x4)
Performance Events: PEBS fmt3+, Skylake events, 32-deep LBR, full-width counters, Intel PMU driver.
... version:                4
... bit width:              48
... generic registers:      4
... value mask:             0000ffffffffffff
... max period:             00007fffffffffff
... fixed-purpose events:   3
... event mask:             000000070000000f
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
x86: Booting SMP configuration:
.... node  #0, CPUs:      #1 #2 #3 #4 #5 #6 #7
smp: Brought up 1 node, 8 CPUs
smpboot: Max logical packages: 10
smpboot: Total of 8 processors activated (35221.20 BogoMIPS)
devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns
futex hash table entries: 2048 (order: 5, 131072 bytes)
xor: automatically using best checksumming function   avx       
pinctrl core: initialized pinctrl subsystem
rcu: INFO: rcu_sched self-detected stall on CPU
rcu:    0-....: (20999 ticks this GP) idle=03e/1/0x4000000000000002 softirq=10/10 fqs=5247 
rcu:     (t=21000 jiffies g=-1175 q=18)
NMI backtrace for cpu 0
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.64 #1
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.2.11 06/13/2019
Call Trace:
 <IRQ>
 0xffffffff81d4c3d5
 0xffffffff81d4f95f
 ? 0xffffffff8102aa32
 0xffffffff81d4f9b8
 0xffffffff8107aafa
 0xffffffff8107a08b
 0xffffffff8107e1e6
 0xffffffff81087ecc
 0xffffffff81e01794
 0xffffffff81e0139f
 </IRQ>
RIP: 0010:0xffffffff8108d4db
Code: ee 89 c7 e8 40 ec cb 00 3b 05 45 63 86 01 73 1e 48 63 f0 49 8b 55 00 48 03 14 f5 00 53 62 82 8b 72 18 40 80 e6 01 74 04 f3 90 <eb> f3 eb d0 48 83 c4 10 5b 5d 41 5c 41 5d 41 5e 41 5f c3 31 c9 85
RSP: 0000:ffffc9000007fae8 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000001
RDX: ffff8897e1063000 RSI: 0000000000000001 RDI: ffff8897e101fc48
RBP: ffff8897e101fc48 R08: 00000000000000ff R09: ffff888000000000
R10: ffffc9000007fb60 R11: 0000000000000001 R12: 000000000001fc00
R13: ffff8897e101fc40 R14: 0000000000000000 R15: ffffffff82625300
 ? 0xffffffff8108d4b9
 ? 0xffffffff8103857d
 ? 0xffffffff8103857d
 0xffffffff8108d507
 0xffffffff8108d51b
 0xffffffff81035988
 0xffffffff81035a8e
 ? 0xffffffff810d853b
 ? 0xffffffff81cb3e73
 ? 0xffffffff81d4c10f
 ? 0xffffffff810cbe08
 0xffffffff81035cb8
 0xffffffff810366f2
 0xffffffff81095dbd
 0xffffffff81cb432c
 ? 0xffffffff82caf70b
 0xffffffff81cb43ea
 ? 0xffffffff82cee8ce
 0xffffffff82cef5c7
 0xffffffff82cee950
 0xffffffff8100040e
 ? 0xffffffff82caf70b
 0xffffffff82cafeed
 ? 0xffffffff81d5c631
 0xffffffff81d5c636
 0xffffffff81e00215

WITH acpi=off and using ttyS1, it still hangs with no output to tty0 or ttyS1.

Sebastian Roth

@george1421 said in rcu_sched stall OR kernel panic on PowerEdge R640:

I still have my kernel dev environment setup. What do we need to enable in the kernel for debugging?

First enable CONFIG_EARLY_PRINTK and CONFIG_EARLY_PRINTK_EFI in the kernel config and edit arch/x86/boot/compressed/eboot.c and search for the function called efi_main. Add print statements like efi_printk(sys_table, "Text output\n"); at various places in that function to find out where exactly it locks up.

Then when using the kernel the OP needs to add earlyprintk=efi (or earlyprintk=vga) to the kernel arguments.

george1421

@djgalloway This is going to be a bit of a hunt and peck game here.

Remove the apci=off command and lets have it use just one cpu by adding in nosmp as a kernel parameter. It looks like it crashes just after it brings up smp.

Also just for clarity, from the printout this is the processor that is currently in use: Intel(R) Xeon(R) Silver 4114 CPU @ 2.20GHz (family: 0x6, model: 0x55, stepping: 0x4)

djgalloway

Kernel command line: loglevel=7 initrd=init.xz root=/dev/ram0 rw ramdisk_size=127000 web=http://10.8.128.2/fog/ consoleblank=0 rootfstype=ext4 console=tty0 console=ttyS1,115200 nosmp mac=e4:43:4b:7d:a9:ba ftp=10.8.128.2 storage=10.8.128.2:/opt/fog/images/dev/ storageip=1p
Misrouted IRQ fixup and polling support enabled
This may significantly impact system performance
Dentry cache hash table entries: 8388608 (order: 14, 67108864 bytes)
Inode-cache hash table entries: 4194304 (order: 13, 33554432 bytes)
Memory: 97288196K/99055148K available (16392K kernel code, 992K rwdata, 4548K rodata, 1056K init, 2416K bss, 1766952K reserved, 0K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
Kernel/User page tables isolation: enabled
rcu: Hierarchical RCU implementation.
rcu:    RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
NR_IRQS: 4352, nr_irqs: 32, preallocated irqs: 16
Console: colour VGA+ 80x25
console [tty0] enabled
console [ttyS1] enabled
ACPI: Core revision 20180810
ACPI: setting ELCR to 0200 (from 0820)
clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635855245 ns
APIC: SMP mode deactivated
APIC: Switch to symmetric I/O mode setup in no SMP routine
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 0 P4D 0 
Oops: 0002 [#1] SMP PTI
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.64 #1
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.2.11 06/13/2019
RIP: 0010:0xffffffff8102d1e6
Code: c2 48 8b 14 d5 00 53 62 82 4a 8b 1c 22 48 85 db 74 d7 3b 2b 75 d3 eb 14 48 8b 1d 25 60 d8 01 48 c7 05 1a 60 d8 01 00 00 00 00 <89> 2b 65 48 89 1d 98 7c fe 7e 65 8b 05 39 1f fe 7e 89 c0 f0 48 0f
RSP: 0000:ffffffff82803e98 EFLAGS: 00010202
RAX: 0000000000000008 RBX: 0000000000000000 RCX: 0000000000000040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff828f36f0
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff81408bd7
R10: 0000000000000000 R11: 000000000000005c R12: 0000000000014e88
R13: ffffffff82d460a0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8897e1000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000002812001 CR4: 00000000000606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 0xffffffff81028ad4
 0xffffffff82cc1652
 0xffffffff82cb691a
 0xffffffff82cafd33
 0xffffffff810000d4
Modules linked in:
CR2: 0000000000000000
---[ end trace f19259880c7c4bbb ]---
RIP: 0010:0xffffffff8102d1e6
Code: c2 48 8b 14 d5 00 53 62 82 4a 8b 1c 22 48 85 db 74 d7 3b 2b 75 d3 eb 14 48 8b 1d 25 60 d8 01 48 c7 05 1a 60 d8 01 00 00 00 00 <89> 2b 65 48 89 1d 98 7c fe 7e 65 8b 05 39 1f fe 7e 89 c0 f0 48 0f
RSP: 0000:ffffffff82803e98 EFLAGS: 00010202
RAX: 0000000000000008 RBX: 0000000000000000 RCX: 0000000000000040
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff828f36f0
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff81408bd7
R10: 0000000000000000 R11: 000000000000005c R12: 0000000000014e88
R13: ffffffff82d460a0 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8897e1000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000002812001 CR4: 00000000000606b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Kernel panic - not syncing: Attempted to kill the idle task!
---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---

Quazz

We may have to enable kernel config option CONFIG_INTEL_IDLE to improve support for certain Intel CPUs.

We may also want to to bump up CONFIG_NR_CPUS from the default of 8 to 512 (common value on modern kernels) at least on the x64 config, though this one shouldn’t cause a crash.

That said, I am doubtful that would resolve this issue.

george1421

@Quazz said in rcu_sched stall OR kernel panic on PowerEdge R640:

We may also want to to bump up CONFIG_NR_CPUS from the default of 8 to 512

I’ve seen this setting in the kernel. I considered requesting the value set to 0 so it uses all available processors, but then I had to think this is for imaging and not a general purposes so having 28 cores available for imaging does really help because at most 4 threads (guess) would be used during imaging since most of the process is single threaded.

Quazz

@george1421 Yes, I think that’s why it was left at 8 in the config, though perhaps some CPUs don’t handle a majority of their cores being ignored very well?

george1421

@Quazz That is surely something we can test.

djgalloway

@george1421 are you working on building a kernel with @Quazz’s suggestions or should I? I don’t have experience building a kernel from scratch but I can probably figure it out.

george1421

@djgalloway Sorry I got side tracked this AM. I almost had it built. Give me a few and I’ll send you a link to the kernel via IM chat.

djgalloway

Here’s the latest output using the debug kernel:

console [ttyS1] enabled
bootconsole [earlyvga0] disabled
ACPI: Core revision 20180810
clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635855245 ns
APIC: Switch to symmetric I/O mode setup
x2apic: IRQ remapping doesn't support X2APIC mode
x2apic disabled
Switched APIC routing to flat.
..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x1fb633008a4, max_idle_ns: 440795292230 ns
Calibrating delay loop (skipped), value calculated using timer frequency.. 4400.00 BogoMIPS (lpj=2200000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Mountpoint-cache hash table entries: 131072 (order: 8, 1048576 bytes)
ENERGY_PERF_BIAS: Set to 'normal', was 'performance'
ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)
process: using mwait in idle threads
Last level iTLB entries: 4KB 64, 2MB 8, 4MB 8
Last level dTLB entries: 4KB 64, 2MB 0, 4MB 0, 1GB 4
Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
Spectre V2 : Mitigation: Full generic retpoline
Spectre V2 : Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch
Spectre V2 : Enabling Restricted Speculation for firmware calls
Spectre V2 : mitigation: Enabling conditional Indirect Branch Prediction Barrier
Spectre V2 : User space: Mitigation: STIBP via seccomp and prctl
Speculative Store Bypass: Mitigation: Speculative Store Bypass disabled via prctl and seccomp
MDS: Mitigation: Clear CPU buffers
Freeing SMP alternatives memory: 52K
smpboot: CPU0: Intel(R) Xeon(R) Silver 4114 CPU @ 2.20GHz (family: 0x6, model: 0x55, stepping: 0x4)
Performance Events: PEBS fmt3+, Skylake events, 32-deep LBR, full-width counters, Intel PMU driver.
... version:                4
... bit width:              48
... generic registers:      4
... value mask:             0000ffffffffffff
... max period:             00007fffffffffff
... fixed-purpose events:   3
... event mask:             000000070000000f
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
x86: Booting SMP configuration:
.... node  #0, CPUs:      #1 #2 #3 #4 #5 #6 #7
smp: Brought up 1 node, 8 CPUs
smpboot: Max logical packages: 10
smpboot: Total of 8 processors activated (35220.85 BogoMIPS)
devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns
futex hash table entries: 2048 (order: 5, 131072 bytes)
xor: automatically using best checksumming function   avx       
pinctrl core: initialized pinctrl subsystem
rcu: INFO: rcu_sched self-detected stall on CPU
rcu:    0-....: (20999 ticks this GP) idle=04a/1/0x4000000000000002 softirq=10/10 fqs=5241 
rcu:     (t=21000 jiffies g=-1175 q=19)
NMI backtrace for cpu 0
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.65 #12
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.2.11 06/13/2019
Call Trace:
 <IRQ>
 0xffffffff81d6ecad
 0xffffffff81d7222f
 ? 0xffffffff8102b073
 0xffffffff81d7228a
 0xffffffff8107ce90
 0xffffffff8107c41d
 0xffffffff810806b4
 0xffffffff8108a34e
 0xffffffff81e017d5
 0xffffffff81e013af
 </IRQ>
RIP: 0010:0xffffffff8108fa1d
Code: 36 48 89 de 89 c7 e8 ca ef cd 00 3b 05 c0 13 86 01 73 24 48 63 f0 49 8b 16 48 03 14 f5 30 83 61 82 8b 72 18 40 80 e6 01 74 04 <f3> 90 eb f3 eb d1 0f 0b e9 72 fe ff ff 48 83 c4 10 5b 5d 41 5c 41
RSP: 0000:ffffc9000007fae0 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000001 RBX: ffff8897e101fac8 RCX: 0000000000000001
RDX: ffff8897e10621c0 RSI: 0000000000000001 RDI: ffff8897e101fac8
RBP: 000000000001fa80 R08: 0000000000000000 R09: 00000000016daed4
R10: ffffc9000007fb58 R11: 000fffffffe00000 R12: 0000000000000001
R13: 0000000000000008 R14: ffff8897e101fac0 R15: 0000000000000000
 ? 0xffffffff81039a

george1421

Just for grins I had the OP boot a 486 kernel I built for another poster for a specific dedicated machine to image with FOG. That kernel gave a bit more details than the full system kernel .

Checking if this processor honours the WP bit even in supervisor mode...Ok.
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1
rcu: Hierarchical RCU implementation.
NR_IRQS: 2304, nr_irqs: 1848, preallocated irqs: 16
Console: colour VGA+ 80x25
console [tty0] enabled
console [ttyS1] enabled
ACPI: Core revision 20180810
clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 79635855245 ns
APIC: Switch to symmetric I/O mode setup
Enabling APIC mode:  Flat.  Using 9 I/O APICs
------------[ cut here ]------------
Kernel BUG at 0xc1028128 [verbose debug info unavailable]
invalid opcode: 0000 [#1] SMP
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.65 #2
Hardware name: Dell Inc. PowerEdge R640/08HT8T, BIOS 2.2.11 06/13/2019
EIP: 0xc1028128

It looks like the kernel is crashing at enabling apic mode or with the apic IO. The clock source hpet also is memorable for some reason.

So the kernel is crashing at the same point. For reference the 486 compatible kernel is also “Linux version 4.19.65”

acpi=ht acpi=oldboot acpi_osi=Linux

noapic

Junkhacker

i was googling the problem a bit and i was curious, will it boot if you remove the raid card?
just trying to understand the source of the panic.

george1421

@Junkhacker @Sebastian-Roth

I was able to get the OP going by doing this and that.

We are not sure if it was this or that that got the kernel to boot. What I did was unlocked the max CPUs (that was capped at in the kernel and I also enabled almost all of the ACPI modules in the kernel. We also tried the acpi_osi=Linux kernel parameter.

We ruled out the acpi_osi=Linux kernel parameter fixing the issue so it must be something I enabled in the kernel. Tomorrow AM I’m going to reset the kernel environment and only unlock the max CPUs. The OP is going to test that new kernel to see if it was unlocking the max cpu or it was the acpi modules I enabled.

Either way I’ll report where we ended up and which kernel change fixed the issue. I have also seen other recent CPU stalls like this that was fixed by setting acpi=off so we may need to move what ever fixed the issue into the main kernel build because new hardware/cpus may require it.

george1421

@developers Here’s the final update on this issue.

I reset my kernel build environment and then created 2 new kernel builds. The first was to remove the imposed CPU limit on the linux kernel this kernel was called bzImageMaxCPU. I reset the kernel build environment and then went through the ACPI settings turning on what I turned on in the debug kernel. This kernel was called bzImageACPI.

The OP tested both and the bzImageMaxCPU was the only kernel that booted on those Dell servers. So in the end @Quazz was right about the CPU not liking some of its cores disabled.

So I would recommend that we add the following settings to the official kernel build

CONFIG_INTEL_IDLE
and
Processor type and features —>

Enable Maximum number of SMP Processors and NUMA Nodes

We have seen a recent uptick in reports of rcu_sched stalls with kernel panics Maybe we are running into this issue more often as the core counts go up on these processors.

Sebastian Roth

@george1421 @Quazz @djgalloway Great work!!! Thanks to you all. I will add this in the next days!

Sebastian Roth

@george1421 @Quazz I found a bit of time to look into this. Adding CONFIG_INTEL_IDLE should be just fine I think. But I am not exactly sure about adding CONFIG_MAXSMP (Enable Maximum number of SMP Processors and NUMA Nodes). Found this topic: https://www.xenomai.org/pipermail/xenomai/2018-July/039297.html

Though I am not convinced this will actually cause trouble it’s still a bit risky. @Testers @Moderators. Would you be able to run a test kernel on several different client machines so we get a feeling of this being troublesome or not?

george1421

@Sebastian-Roth I can test it here, but I don’t have a system that is causing this rcu_sched issue. But I can surely test it against our current fleet of Dell systems to see if it does any harm.

We can also hold this “test” kernel in reserve in case this issue comes up again if you don’t want to release it as general availability. What I would not like to see is having a special kernel for this, and a different special kernel for that.

Sebastian Roth

@george1421 said in rcu_sched stall OR kernel panic on PowerEdge R640:

We can also hold this “test” kernel in reserve in case this issue comes up again if you don’t want to release it as general availability.

Don’t get me wrong on this. I am more than happy to make this the default kernel for everyone. It comes at low cost. But I’d like to see this tested on several different machines (PC as well as notebooks and even servers if possible) before we make it the new default kernel.

rcu_sched stall OR kernel panic on PowerEdge R640

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