Oops from calibrate_delay_is_known on qemu machine with Linux v4.5-1523-g271ecc5253e2

[Josh Boyer]

Hi Thomas,

We've had a report [1] of the mainline kernel crashing on a single-cpu
QEMU machine (not kvm) in Fedora.  It looks as if the emulated machine
is failing to provide a TSC and the calibrate_delay_is_known function
is passing NULL to cpumask_any_but for the mask parameter.  At least
that's all I've been able to discern thus far.

I was wondering if you had any insight into this issue, given your
recent commit to change calibrate_delay_is_known to use
topology_core_cpumask.  The backtrace is below.

josh

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1318596

\x1b[2J[    0.000000] Linux version 4.6.0-0.rc0.git5.1.fc25.x86_64
(mockbuild@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx) (gcc version 6.0.0
20160311 (Red Hat 6.0.0-0.16) (GCC) ) #1 SMP Wed Mar 16 23:42:51 UTC
2016
[    0.000000] Command line: panic=1 console=ttyS0 udevtimeout=6000
udev.event-timeout=6000 no_timer_check acpi=off printk.time=1
cgroup_disable=memory root=/dev/sdb selinux=0 guestfs_verbose=1
TERM=vt100
[    0.000000] x86/fpu: Legacy x87 FPU detected.
[    0.000000] x86/fpu: Using 'eager' FPU context switches.
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009f7ff] usable
[    0.000000] BIOS-e820: [mem 0x000000000009f800-0x000000000009ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001f3fbfff] usable
[    0.000000] BIOS-e820: [mem 0x000000001f3fc000-0x000000001f3fffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved
[    0.000000] NX (Execute Disable) protection: active
[    0.000000] SMBIOS 2.8 present.
[    0.000000] e820: last_pfn = 0x1f3fc max_arch_pfn = 0x400000000
[    0.000000] x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WC  UC- WT
[    0.000000] found SMP MP-table at [mem 0x000f6bb0-0x000f6bbf]
mapped at [ffff8800000f6bb0]
[    0.000000] Scanning 1 areas for low memory corruption
[    0.000000] RAMDISK: [mem 0x1f200000-0x1f3effff]
[    0.000000] No NUMA configuration found
[    0.000000] Faking a node at [mem 0x0000000000000000-0x000000001f3fbfff]
[    0.000000] NODE_DATA(0) allocated [mem 0x1f1e9000-0x1f1fffff]
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
[    0.000000]   DMA32    [mem 0x0000000001000000-0x000000001f3fbfff]
[    0.000000]   Normal   empty
[    0.000000]   Device   empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009efff]
[    0.000000]   node   0: [mem 0x0000000000100000-0x000000001f3fbfff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000001000-0x000000001f3fbfff]
[    0.000000] SFI: Simple Firmware Interface v0.81 http://simplefirmware.org
[    0.000000] Intel MultiProcessor Specification v1.4
[    0.000000] MPTABLE: OEM ID: BOCHSCPU
[    0.000000] MPTABLE: Product ID: 0.1
[    0.000000] MPTABLE: APIC at: 0xFEE00000
[    0.000000] Processor #0 (Bootup-CPU)
[    0.000000] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[    0.000000] Processors: 1
[    0.000000] smpboot: Allowing 1 CPUs, 0 hotplug CPUs
[    0.000000] PM: Registered nosave memory: [mem 0x00000000-0x00000fff]
[    0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[    0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff]
[    0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[    0.000000] e820: [mem 0x1f400000-0xfffbffff] available for PCI devices
[    0.000000] Booting paravirtualized kernel on bare hardware
[    0.000000] clocksource: refined-jiffies: mask: 0xffffffff
max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns
[    0.000000] setup_percpu: NR_CPUS:8192 nr_cpumask_bits:1
nr_cpu_ids:1 nr_node_ids:1
[    0.000000] PERCPU: Embedded 483 pages/cpu @ffff88001ee00000
s1937688 r8192 d32488 u2097152
[    0.000000] Built 1 zonelists in Node order, mobility grouping on.
Total pages: 125877
[    0.000000] Policy zone: DMA32
[    0.000000] Kernel command line: panic=1 console=ttyS0
udevtimeout=6000 udev.event-timeout=6000 no_timer_check acpi=off
printk.time=1 cgroup_disable=memory root=/dev/sdb selinux=0
guestfs_verbose=1 TERM=vt100
[    0.000000] PID hash table entries: 2048 (order: 2, 16384 bytes)
[    0.000000] Memory: 461856K/511592K available (8982K kernel code,
1793K rwdata, 3488K rodata, 3700K init, 16816K bss, 49736K reserved,
0K cma-reserved)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] Running RCU self tests
[    0.000000] Hierarchical RCU implementation.
[    0.000000] \tRCU lockdep checking is enabled.
[    0.000000] \tBuild-time adjustment of leaf fanout to 64.
[    0.000000] \tRCU restricting CPUs from NR_CPUS=8192 to nr_cpu_ids=1.
[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=64, nr_cpu_ids=1
[    0.000000] kmemleak: Kernel memory leak detector disabled
[    0.000000] NR_IRQS:524544 nr_irqs:256 16
[    0.000000] \tOffload RCU callbacks from all CPUs
[    0.000000] \tOffload RCU callbacks from CPUs: 0.
[    0.000000] Console: colour *CGA 80x25
[    0.000000] console [ttyS0] enabled
[    0.000000] Lock dependency validator: Copyright (c) 2006 Red Hat,
Inc., Ingo Molnar
[    0.000000] ... MAX_LOCKDEP_SUBCLASSES:  8
[    0.000000] ... MAX_LOCK_DEPTH:          48
[    0.000000] ... MAX_LOCKDEP_KEYS:        8191
[    0.000000] ... CLASSHASH_SIZE:          4096
[    0.000000] ... MAX_LOCKDEP_ENTRIES:     32768
[    0.000000] ... MAX_LOCKDEP_CHAINS:      65536
[    0.000000] ... CHAINHASH_SIZE:          32768
[    0.000000]  memory used by lock dependency info: 8671 kB
[    0.000000]  per task-struct memory footprint: 2688 bytes
[    0.000000] tsc: Unable to calibrate against PIT
[    0.000000] tsc: No reference (HPET/PMTIMER) available
[    0.000000] tsc: Marking TSC unstable due to could not calculate TSC khz
[    0.010000] BUG: unable to handle kernel NULL pointer dereference
at           (null)
[    0.010000] IP: [<ffffffff814698b5>] _find_next_bit.part.0+0x15/0x70
[    0.010000] PGD 0
[    0.010000] Oops: 0000 [#1] SMP
[    0.010000] Modules linked in:
[    0.010000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.6.0-0.rc0.git5.1.fc25.x86_64 #1
[    0.010000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.9.0-2.fc24 04/01/2014
[    0.010000] task: ffffffff81e0d580 ti: ffffffff81e00000 task.ti:
ffffffff81e00000
[    0.010000] RIP: 0010:[<ffffffff814698b5>]  [<ffffffff814698b5>]
_find_next_bit.part.0+0x15/0x70
[    0.010000] RSP: 0000:ffffffff81e03e40  EFLAGS: 00000246
[    0.010000] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[    0.010000] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
[    0.010000] RBP: ffffffff81e03e50 R08: ffffffffffffffff R09: 0000000000000000
[    0.010000] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
[    0.010000] R13: ffffffff82248960 R14: ffffffff822562e0 R15: 0000000000000000
[    0.010000] FS:  0000000000000000(0000) GS:ffff88001ee00000(0000)
knlGS:0000000000000000
[    0.010000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.010000] CR2: 0000000000000000 CR3: 0000000001e06000 CR4: 00000000000006b0
[    0.010000] Stack:
[    0.010000]  ffffffff81e03e50 ffffffff81469928 ffffffff81e03e70
ffffffff81453d56
[    0.010000]  0000000000000000 ffff88001f3fa780 ffffffff81e03e80
ffffffff81040495
[    0.010000]  ffffffff81e03f40 ffffffff8100285a ffffffff810eefb3
ffffffff00000000
[    0.010000] Call Trace:
[    0.010000]  [<ffffffff81469928>] ? find_next_bit+0x18/0x20
[    0.010000]  [<ffffffff81453d56>] cpumask_any_but+0x26/0x50
[    0.010000]  [<ffffffff81040495>] calibrate_delay_is_known+0x45/0x80
[    0.010000]  [<ffffffff8100285a>] calibrate_delay+0xfa/0x690
[    0.010000]  [<ffffffff810eefb3>] ? sched_clock_init+0x13/0x90
[    0.010000]  [<ffffffff81111525>] ? trace_hardirqs_on_caller+0xf5/0x1b0
[    0.010000]  [<ffffffff81146743>] ? ktime_get+0xb3/0x150
[    0.010000]  [<ffffffff810eefb3>] ? sched_clock_init+0x13/0x90
[    0.010000]  [<ffffffff8219cf7a>] start_kernel+0x3db/0x4a3
[    0.010000]  [<ffffffff8219c120>] ? early_idt_handler_array+0x120/0x120
[    0.010000]  [<ffffffff8219c32c>] x86_64_start_reservations+0x2a/0x2c
[    0.010000]  [<ffffffff8219c47a>] x86_64_start_kernel+0x14c/0x16f
[    0.010000] Code: d0 48 0f 47 c2 5d c3 0f 1f 44 00 00 66 2e 0f 1f
84 00 00 00 00 00 48 89 c8 48 89 d1 49 c7 c0 ff ff ff ff 48 c1 e9 06
49 89 c1 55 <4c> 33 0c cf 89 d1 48 83 e2 c0 49 d3 e0 48 89 e5 4c 89 c1
4c 21
[    0.010000] RIP  [<ffffffff814698b5>] _find_next_bit.part.0+0x15/0x70
[    0.010000]  RSP <ffffffff81e03e40>
[    0.010000] CR2: 0000000000000000
[    0.010000] ---[ end trace 1f7208cba1f1b54f ]---
[    0.010000] Kernel panic - not syncing: Attempted to kill the idle task!