kdump kernel panics on Bionic

[Daniel Axtens]

The kdump/crashdump kernel is panicing during boot on Bionic.

1) Install the daily Bionic server or desktop ISO
2) apt install linux-crashdump, say yes to kdump being enabled
3) Reboot so as to boot with the correct kernel parameter
4) Run:
    root@bionic-server:~# echo 1 > /proc/sys/kernel/sysrq
    root@bionic-server:~# echo c > /proc/sysrq-trigger
5) Observe that the crashdump kernel panics before booting with an out-of-memory error. Log below.

If I replace the bionic image with the artful cloud image, and repeat steps 2-4, the crashdump kernel boots and successfully stores the vmcore.

The full log:

[ 54.424512] sysrq: SysRq : Trigger a crash
[ 54.427899] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[ 54.433915] IP: sysrq_handle_crash+0x16/0x20
[ 54.437157] PGD 0 P4D 0
[ 54.439292] Oops: 0002 [#1] SMP PTI
[ 54.444571] Modules linked in: snd_hda_codec_generic crct10dif_pclmul crc32_pclmul snd_hda_intel ghash_clmulni_intel snd_hda_codec snd_hda_core snd_hwdep input_leds joydev snd_pcm serio_raw snd_timer snd soundcore qemu_fw_cfg mac_hid sch_fq_codel ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0 multipath linear hid_generic usbhid hid qxl aesni_intel ttm drm_kms_helper aes_x86_64 crypto_simd cryptd glue_helper syscopyarea sysfillrect sysimgblt fb_sys_fops psmouse virtio_blk virtio_net drm i2c_piix4 pata_acpi floppy
[ 54.468925] CPU: 0 PID: 1075 Comm: bash Not tainted 4.15.0-15-generic #16-Ubuntu
[ 54.470377] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 54.472016] RIP: 0010:sysrq_handle_crash+0x16/0x20
[ 54.472891] RSP: 0018:ffffa3a000643e30 EFLAGS: 00010286
[ 54.473826] RAX: ffffffff917e0950 RBX: ffffffff92787200 RCX: 0000000000000000
[ 54.475092] RDX: 0000000000000000 RSI: ffff90dfbfc16498 RDI: 0000000000000063
[ 54.476182] RBP: ffffa3a000643e30 R08: 0000000000000000 R09: 000000000000022b
[ 54.477272] R10: 0000000000000001 R11: ffffffff92b5280d R12: 0000000000000004
[ 54.478361] R13: 0000000000000063 R14: 0000000000000002 R15: ffff90dfbab0ef00
[ 54.479456] FS: 00007ff6248af740(0000) GS:ffff90dfbfc00000(0000) knlGS:0000000000000000
[ 54.480602] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 54.481379] CR2: 0000000000000000 CR3: 000000007bcb2006 CR4: 00000000003606f0
[ 54.482341] Call Trace:
[ 54.482690] __handle_sysrq+0x9f/0x170
[ 54.483207] write_sysrq_trigger+0x34/0x40
[ 54.483775] proc_reg_write+0x45/0x70
[ 54.484281] __vfs_write+0x1b/0x40
[ 54.484751] vfs_write+0xb1/0x1a0
[ 54.485208] SyS_write+0x55/0xc0
[ 54.485669] do_syscall_64+0x73/0x130
[ 54.486156] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[ 54.486784] RIP: 0033:0x7ff623f84154
[ 54.487328] RSP: 002b:00007ffe5f399678 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 54.488272] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007ff623f84154
[ 54.489179] RDX: 0000000000000002 RSI: 000055a5a49151c0 RDI: 0000000000000001
[ 54.490313] RBP: 000055a5a49151c0 R08: 000000000000000a R09: 0000000000000001
[ 54.491179] R10: 000000000000000a R11: 0000000000000246 R12: 00007ff624260760
[ 54.492311] R13: 0000000000000002 R14: 00007ff62425c2a0 R15: 00007ff62425b760
[ 54.493124] Code: e7 e8 9f fb ff ff e9 c0 fe ff ff 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 55 c7 05 a8 a7 36 01 01 00 00 00 48 89 e5 0f ae f8 <c6> 04 25 00 00 00 00 01 5d c3 0f 1f 44 00 00 55 c7 05 40 1f e8
[ 54.496461] RIP: sysrq_handle_crash+0x16/0x20 RSP: ffffa3a000643e30
[ 54.497393] CR2: 0000000000000000
[ 0.000000] Linux version 4.15.0-15-generic (buildd@lgw01-amd64-050) (gcc version 7.3.0 (Ubuntu 7.3.0-14ubuntu1)) #16-Ubuntu SMP Wed Apr 4 13:58:14 UTC 2018 (Ubuntu 4.15.0-15.16-generic 4.15.15)
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-15-generic root=UUID=3e45b7ec-412a-11e8-a844-5254003896a5 ro maybe-ubiquity console=ttyS0 nr_cpus=1 systemd.unit=kdump-tools.service irqpoll nousb ata_piix.prefer_ms_hyperv=0 elfcorehdr=802164K
[ 0.000000] KERNEL supported cpus:
[ 0.000000] Intel GenuineIntel
[ 0.000000] AMD AuthenticAMD
[ 0.000000] Centaur CentaurHauls
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256
[ 0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'standard' format.
[ 0.000000] e820: BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000001000-0x000000000009fbff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000029000000-0x0000000030f5cfff] usable
[ 0.000000] BIOS-e820: [mem 0x0000000030fffc00-0x0000000030ffffff] usable
[ 0.000000] NX (Execute Disable) protection: active
[ 0.000000] random: fast init done
[ 0.000000] SMBIOS 2.8 present.
[ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 0.000000] Hypervisor detected: KVM
[ 0.000000] e820: last_pfn = 0x31000 max_arch_pfn = 0x400000000
[ 0.000000] x86/PAT: Configuration [0-7]: WB WC UC- UC WB WP UC- WT
[ 0.000000] x2apic: enabled by BIOS, switching to x2apic ops
[ 0.000000] found SMP MP-table at [mem 0x000f6a50-0x000f6a5f] mapped at [ (ptrval)]
[ 0.000000] Scanning 1 areas for low memory corruption
[ 0.000000] RAMDISK: [mem 0x2d66e000-0x2effffff]
[ 0.000000] ACPI: Early table checksum verification disabled
[ 0.000000] ACPI: RSDP 0x00000000000F6870 000014 (v00 BOCHS )
[ 0.000000] ACPI: RSDT 0x000000007FFE1523 00002C (v01 BOCHS BXPCRSDT 00000001 BXPC 00000001)
[ 0.000000] ACPI: FACP 0x000000007FFE13B7 000074 (v01 BOCHS BXPCFACP 00000001 BXPC 00000001)
[ 0.000000] ACPI: DSDT 0x000000007FFE0040 001377 (v01 BOCHS BXPCDSDT 00000001 BXPC 00000001)
[ 0.000000] ACPI: FACS 0x000000007FFE0000 000040
[ 0.000000] ACPI: APIC 0x000000007FFE14AB 000078 (v01 BOCHS BXPCAPIC 00000001 BXPC 00000001)
[ 0.000000] Setting APIC routing to cluster x2apic.
[ 0.000000] No NUMA configuration found
[ 0.000000] Faking a node at [mem 0x0000000000000000-0x0000000030ffffff]
[ 0.000000] NODE_DATA(0) allocated [mem 0x30f32000-0x30f5cfff]
[ 0.000000] kvm-clock: cpu 0, msr 0:30eb1001, primary cpu clock
[ 0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[ 0.000000] kvm-clock: using sched offset of 574593506761 cycles
[ 0.000000] clocksource: kvm-clock: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x0000000000001000-0x0000000000ffffff]
[ 0.000000] DMA32 [mem 0x0000000001000000-0x0000000030ffffff]
[ 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 0x0000000029000000-0x0000000030f5cfff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000001000-0x0000000030f5cfff]
[ 0.000000] Reserved but unavailable: 98 pages
[ 0.000000] ACPI: PM-Timer IO Port: 0x608
[ 0.000000] ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
[ 0.000000] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 5 global_irq 5 high level)
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 10 global_irq 10 high level)
[ 0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 11 global_irq 11 high level)
[ 0.000000] Using ACPI (MADT) for SMP configuration information
[ 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 0x0009f000-0x28ffffff]
[ 0.000000] PM: Registered nosave memory: [mem 0x30f5d000-0x30ffffff]
[ 0.000000] e820: [mem 0x31000000-0xffffffff] available for PCI devices
[ 0.000000] Booting paravirtualized kernel on KVM
[ 0.000000] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns
[ 0.000000] setup_percpu: NR_CPUS:8192 nr_cpumask_bits:1 nr_cpu_ids:1 nr_node_ids:1
[ 0.000000] percpu: Embedded 46 pages/cpu @ (ptrval) s151552 r8192 d28672 u2097152
[ 0.000000] KVM setup async PF for cpu 0
[ 0.000000] kvm-stealtime: cpu 0, msr 30c24040
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 32229
[ 0.000000] Policy zone: DMA32
[ 0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-15-generic root=UUID=3e45b7ec-412a-11e8-a844-5254003896a5 ro maybe-ubiquity console=ttyS0 nr_cpus=1 systemd.unit=kdump-tools.service irqpoll nousb ata_piix.prefer_ms_hyperv=0 elfcorehdr=802164K
[ 0.000000] Misrouted IRQ fixup and polling support enabled
[ 0.000000] This may significantly impact system performance
[ 0.000000] Memory: 69764K/131052K available (12300K kernel code, 2472K rwdata, 4228K rodata, 2404K init, 2416K bss, 61288K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] Kernel/User page tables isolation: enabled
[ 0.000000] ftrace: allocating 39206 entries in 154 pages
[ 0.004000] Hierarchical RCU implementation.
[ 0.004000] RCU restricting CPUs from NR_CPUS=8192 to nr_cpu_ids=1.
[ 0.004000] Tasks RCU enabled.
[ 0.004000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[ 0.004000] NR_IRQS: 524544, nr_irqs: 256, preallocated irqs: 16
[ 0.004000] Console: colour VGA+ 80x25
[ 0.004000] console [ttyS0] enabled
[ 0.004000] ACPI: Core revision 20170831
[ 0.004000] ACPI: 1 ACPI AML tables successfully acquired and loaded
[ 0.004000] APIC: Switch to symmetric I/O mode setup
[ 0.004000] Switched APIC routing to physical x2apic.
[ 0.004000] WARNING: CPU: 0 PID: 0 at /build/linux-18ur8S/linux-4.15.0/arch/x86/kernel/apic/apic.c:1516 setup_local_APIC+0x270/0x3a0
[ 0.004000] Modules linked in:
[ 0.004000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-15-generic #16-Ubuntu
[ 0.004000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 0.004000] RIP: 0010:setup_local_APIC+0x270/0x3a0
[ 0.004000] RSP: 0000:ffffffffb5203e60 EFLAGS: 00010282
[ 0.004000] RAX: 00000141bdd96846 RBX: 0000000000000000 RCX: fffffffffffff252
[ 0.004000] RDX: 0000014100000000 RSI: 0000000000000000 RDI: 0000000000004000
[ 0.004000] RBP: ffffffffb5203ea0 R08: 6465686374697753 R09: 0000000000000083
[ 0.004000] R10: 0000000000000040 R11: 756f722043495041 R12: 0000000000000000
[ 0.004000] R13: 0000000000000001 R14: 00000000000000f0 R15: 00000000ffffffff
[ 0.004000] FS: 0000000000000000(0000) GS:ffff923930c00000(0000) knlGS:0000000000000000
[ 0.004000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 0.004000] CR2: 00000000ffffffff CR3: 000000002ca0a001 CR4: 00000000000606b0
[ 0.004000] Call Trace:
[ 0.004000] apic_bsp_setup+0x60/0x80
[ 0.004000] apic_intr_mode_init+0x191/0x194
[ 0.004000] x86_late_time_init+0x1b/0x22
[ 0.004000] start_kernel+0x43f/0x4fd
[ 0.004000] x86_64_start_reservations+0x24/0x26
[ 0.004000] x86_64_start_kernel+0x74/0x77
[ 0.004000] secondary_startup_64+0xa5/0xb0
[ 0.004000] Code: 0d 26 ff 5f 01 85 c9 74 29 0f 31 c1 e1 0a 48 03 4d c0 48 c1 e2 20 48 09 d0 48 29 c1 48 89 4d c8 48 83 7d c8 00 0f 8f 5a fe ff ff <0f> 0b e9 f9 fe ff ff 48 83 6d c8 01 eb e7 e8 cd 33 00 00 48 83
[ 0.004000] ---[ end trace 614376af8502f57a ]---
[ 0.004000] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[ 0.004000] tsc: Detected 2400.000 MHz processor
[ 0.004000] Spurious LAPIC timer interrupt on cpu 0
[ 0.004658] Calibrating delay loop (skipped) preset value.. 4800.00 BogoMIPS (lpj=9600000)
[ 0.005085] pid_max: default: 32768 minimum: 301
[ 0.005725] Security Framework initialized
[ 0.006273] Yama: becoming mindful.
[ 0.006751] AppArmor: AppArmor initialized
[ 0.008050] Dentry cache hash table entries: 16384 (order: 5, 131072 bytes)
[ 0.008952] Inode-cache hash table entries: 8192 (order: 4, 65536 bytes)
[ 0.009873] Mount-cache hash table entries: 512 (order: 0, 4096 bytes)
[ 0.010665] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes)
[ 0.012215] CPU: Physical Processor ID: 0
[ 0.012757] mce: CPU supports 10 MCE banks
[ 0.013425] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0
[ 0.013991] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0, 1GB 0
[ 0.014640] Spectre V2 : Mitigation: Full generic retpoline
[ 0.015218] Spectre V2 : Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier
[ 0.016005] Spectre V2 : Enabling Restricted Speculation for firmware calls
[ 0.023242] Freeing SMP alternatives memory: 36K
[ 0.024680] smpboot: CPU0: Intel Core Processor (Broadwell, no TSX, IBRS) (family: 0x6, model: 0x3d, stepping: 0x2)
[ 0.026015] Performance Events: unsupported p6 CPU model 61 no PMU driver, software events only.
[ 0.027128] Hierarchical SRCU implementation.
[ 0.028000] NMI watchdog: Perf event create on CPU 0 failed with -2
[ 0.028004] NMI watchdog: Perf NMI watchdog permanently disabled
[ 0.028783] smp: Bringing up secondary CPUs ...
[ 0.029346] smp: Brought up 1 node, 1 CPU
[ 0.029852] smpboot: Max logical packages: 1
[ 0.030388] smpboot: Total of 1 processors activated (4800.00 BogoMIPS)
[ 0.031327] devtmpfs: initialized
[ 0.031788] x86/mm: Memory block size: 128MB
[ 0.032090] evm: security.selinux
[ 0.032453] evm: security.SMACK64
[ 0.032868] evm: security.SMACK64EXEC
[ 0.033342] evm: security.SMACK64TRANSMUTE
[ 0.033906] evm: security.SMACK64MMAP
[ 0.034862] evm: security.apparmor
[ 0.035334] evm: security.ima
[ 0.035733] evm: security.capability
[ 0.036121] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.037323] futex hash table entries: 256 (order: 2, 16384 bytes)
[ 0.038130] pinctrl core: initialized pinctrl subsystem
[ 0.038934] RTC time: 4:10:32, date: 04/16/18
[ 0.039557] NET: Registered protocol family 16
[ 0.040074] audit: initializing netlink subsys (disabled)
[ 0.040829] cpuidle: using governor ladder
[ 0.041344] cpuidle: using governor menu
[ 0.041891] ACPI: bus type PCI registered
[ 0.042396] acpiphp: ACPI Hot Plug PCI Controller Driver version: 0.5
[ 0.043311] PCI: Using configuration type 1 for base access
[ 0.044051] audit: type=2000 audit(1523851830.179:1): state=initialized audit_enabled=0 res=1
[ 0.046009] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages
[ 0.047039] ACPI: Added _OSI(Module Device)
[ 0.047599] ACPI: Added _OSI(Processor Device)
[ 0.048009] ACPI: Added _OSI(3.0 _SCP Extensions)
[ 0.048465] ACPI: Added _OSI(Processor Aggregator Device)
[ 0.049953] ACPI: Interpreter enabled
[ 0.050549] ACPI: (supports S0 S5)
[ 0.051002] ACPI: Using IOAPIC for interrupt routing
[ 0.051681] PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug
[ 0.052150] ACPI: Enabled 2 GPEs in block 00 to 0F
[ 0.054647] ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
[ 0.055429] acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI]
[ 0.056027] acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM
[ 0.056871] acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge.
[ 0.058508] acpiphp: Slot [3] registered
[ 0.059021] acpiphp: Slot [4] registered
[ 0.059551] acpiphp: Slot [6] registered
[ 0.060023] acpiphp: Slot [7] registered
[ 0.060534] acpiphp: Slot [8] registered
[ 0.061048] acpiphp: Slot [9] registered
[ 0.061559] acpiphp: Slot [10] registered
[ 0.062082] acpiphp: Slot [11] registered
[ 0.062602] acpiphp: Slot [12] registered
[ 0.063129] acpiphp: Slot [13] registered
[ 0.063703] acpiphp: Slot [14] registered
[ 0.064024] acpiphp: Slot [15] registered
[ 0.064553] acpiphp: Slot [16] registered
[ 0.065074] acpiphp: Slot [17] registered
[ 0.065594] acpiphp: Slot [18] registered
[ 0.066119] acpiphp: Slot [19] registered
[ 0.066704] acpiphp: Slot [20] registered
[ 0.067223] acpiphp: Slot [21] registered
[ 0.067746] acpiphp: Slot [22] registered
[ 0.068020] acpiphp: Slot [23] registered
[ 0.068544] acpiphp: Slot [24] registered
[ 0.069063] acpiphp: Slot [25] registered
[ 0.069582] acpiphp: Slot [26] registered
[ 0.070103] acpiphp: Slot [27] registered
[ 0.070637] acpiphp: Slot [28] registered
[ 0.071160] acpiphp: Slot [29] registered
[ 0.071688] acpiphp: Slot [30] registered
[ 0.072022] acpiphp: Slot [31] registered
[ 0.072396] PCI host bridge to bus 0000:00
[ 0.072861] pci_bus 0000:00: root bus resource [io 0x0000-0x0cf7 window]
[ 0.074286] pci_bus 0000:00: root bus resource [io 0x0d00-0xffff window]
[ 0.075193] pci_bus 0000:00: root bus resource [mem 0x000a0000-0x000bffff window]
[ 0.076043] pci_bus 0000:00: root bus resource [mem 0x80000000-0xfebfffff window]
[ 0.077009] pci_bus 0000:00: root bus resource [bus 00-ff]
[ 0.086359] pci 0000:00:01.1: legacy IDE quirk: reg 0x10: [io 0x01f0-0x01f7]
[ 0.087267] pci 0000:00:01.1: legacy IDE quirk: reg 0x14: [io 0x03f6]
[ 0.088007] pci 0000:00:01.1: legacy IDE quirk: reg 0x18: [io 0x0170-0x0177]
[ 0.090235] pci 0000:00:01.1: legacy IDE quirk: reg 0x1c: [io 0x0376]
[ 0.091976] pci 0000:00:01.3: quirk: [io 0x0600-0x063f] claimed by PIIX4 ACPI
[ 0.092014] pci 0000:00:01.3: quirk: [io 0x0700-0x070f] claimed by PIIX4 SMB
[ 0.256681] ACPI: PCI Interrupt Link [LNKA] (IRQs 5 *10 11)
[ 0.257568] ACPI: PCI Interrupt Link [LNKB] (IRQs 5 10 *11)
[ 0.258355] ACPI: PCI Interrupt Link [LNKC] (IRQs 5 10 *11)
[ 0.259208] ACPI: PCI Interrupt Link [LNKD] (IRQs 5 *10 11)
[ 0.259958] ACPI: PCI Interrupt Link [LNKS] (IRQs *9)
[ 0.260237] SCSI subsystem initialized
[ 0.260777] pci 0000:00:02.0: vgaarb: setting as boot VGA device
[ 0.261530] pci 0000:00:02.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[ 0.262607] pci 0000:00:02.0: vgaarb: bridge control possible
[ 0.263744] vgaarb: loaded
[ 0.264027] ACPI: bus type USB registered
[ 0.264544] usbcore: registered new interface driver usbfs
[ 0.265242] usbcore: registered new interface driver hub
[ 0.265943] usbcore: registered new device driver usb
[ 0.266625] EDAC MC: Ver: 3.0.0
[ 0.267306] PCI: Using ACPI for IRQ routing
[ 0.268122] NetLabel: Initializing
[ 0.268555] NetLabel: domain hash size = 128
[ 0.269200] NetLabel: protocols = UNLABELED CIPSOv4 CALIPSO
[ 0.269974] NetLabel: unlabeled traffic allowed by default
[ 0.271321] clocksource: Switched to clocksource kvm-clock
[ 0.275088] VFS: Disk quotas dquot_6.6.0
[ 0.275625] VFS: Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
[ 0.276609] AppArmor: AppArmor Filesystem Enabled
[ 0.277137] pnp: PnP ACPI init
[ 0.277788] pnp: PnP ACPI: found 5 devices
[ 0.283471] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns
[ 0.285081] NET: Registered protocol family 2
[ 0.286386] TCP established hash table entries: 1024 (order: 1, 8192 bytes)
[ 0.287341] TCP bind hash table entries: 1024 (order: 2, 16384 bytes)
[ 0.288219] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.289080] UDP hash table entries: 256 (order: 1, 8192 bytes)
[ 0.289840] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes)
[ 0.290683] NET: Registered protocol family 1
[ 0.291262] pci 0000:00:00.0: Limiting direct PCI/PCI transfers
[ 0.292071] pci 0000:00:01.0: Activating ISA DMA hang workarounds
[ 0.292915] pci 0000:00:02.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
[ 0.310818] ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 10
[ 0.350037] ACPI: PCI Interrupt Link [LNKB] enabled at IRQ 11
[ 0.388077] ACPI: PCI Interrupt Link [LNKC] enabled at IRQ 11
[ 0.424907] ACPI: PCI Interrupt Link [LNKD] enabled at IRQ 10
[ 0.445878] Unpacking initramfs...
[ 0.648882] swapper/0 invoked oom-killer: gfp_mask=0x14200c2(GFP_HIGHUSER), nodemask=(null), order=0, oom_score_adj=0
[ 0.650134] swapper/0 cpuset=/ mems_allowed=0
[ 0.650685] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.15.0-15-generic #16-Ubuntu
[ 0.651622] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 0.652003] Call Trace:
[ 0.652003] dump_stack+0x63/0x8b
[ 0.652003] dump_header+0x71/0x285
[ 0.652003] out_of_memory+0x3d3/0x4f0
[ 0.652003] __alloc_pages_slowpath+0xa93/0xe60
[ 0.652003] __alloc_pages_nodemask+0x263/0x280
[ 0.652003] alloc_page_interleave+0x17/0x70
[ 0.652003] ? __next_node_in+0x31/0x50
[ 0.652003] alloc_pages_current+0xc8/0xe0
[ 0.652003] __page_cache_alloc+0x81/0xa0
[ 0.652003] pagecache_get_page+0x9b/0x2a0
[ 0.652003] grab_cache_page_write_begin+0x26/0x40
[ 0.652003] simple_write_begin+0x29/0x1b0
[ 0.652003] generic_perform_write+0xb3/0x1b0
[ 0.652003] __generic_file_write_iter+0x1aa/0x1d0
[ 0.652003] generic_file_write_iter+0xe9/0x1f0
[ 0.652003] new_sync_write+0xe7/0x140
[ 0.652003] __vfs_write+0x29/0x40
[ 0.652003] vfs_write+0xb1/0x1a0
[ 0.652003] ? md_run_setup+0x99/0x99
[ 0.652003] SyS_write+0x55/0xc0
[ 0.652003] ? do_name+0x127/0x287
[ 0.652003] xwrite+0x2e/0x61
[ 0.652003] do_copy+0x8f/0xbd
[ 0.652003] write_buffer+0x2b/0x3c
[ 0.652003] flush_buffer+0x39/0x91
[ 0.652003] __gunzip+0x277/0x31b
[ 0.652003] ? bunzip2+0x3be/0x3be
[ 0.652003] ? write_buffer+0x3c/0x3c
[ 0.652003] ? md_run_setup+0x99/0x99
[ 0.652003] ? __gunzip+0x31b/0x31b
[ 0.652003] gunzip+0x11/0x13
[ 0.652003] ? md_run_setup+0x99/0x99
[ 0.652003] unpack_to_rootfs+0x187/0x2c0
[ 0.652003] ? md_run_setup+0x99/0x99
[ 0.652003] ? unpack_to_rootfs+0x2c0/0x2c0
[ 0.652003] ? set_debug_rodata+0x17/0x17
[ 0.652003] populate_rootfs+0x61/0x10f
[ 0.652003] do_one_initcall+0x52/0x19f
[ 0.652003] kernel_init_freeable+0x1af/0x251
[ 0.652003] ? rest_init+0xb0/0xb0
[ 0.652003] kernel_init+0xe/0x100
[ 0.652003] ret_from_fork+0x35/0x40
[ 0.670203] Mem-Info:
[ 0.670462] active_anon:0 inactive_anon:0 isolated_anon:0
[ 0.670462] active_file:0 inactive_file:0 isolated_file:0
[ 0.670462] unevictable:13731 dirty:0 writeback:0 unstable:0
[ 0.670462] slab_reclaimable:2163 slab_unreclaimable:667
[ 0.670462] mapped:0 shmem:0 pagetables:0 bounce:0
[ 0.670462] free:328 free_pcp:12 free_cma:0
[ 0.675622] Node 0 active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:54924kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no
[ 0.679635] Node 0 DMA free:272kB min:8kB low:8kB high:8kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:4kB unevictable:264kB writepending:0kB present:632kB managed:548kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
[ 0.683356] lowmem_reserve[]: 0 67 67 67 67
[ 0.683943] Node 0 DMA32 free:1040kB min:1044kB low:1304kB high:1564kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:54660kB writepending:0kB present:130420kB managed:69252kB mlocked:0kB kernel_stack:496kB pagetables:0kB bounce:0kB free_pcp:48kB local_pcp:48kB free_cma:0kB
[ 0.687508] lowmem_reserve[]: 0 0 0 0 0
[ 0.688055] Node 0 DMA: 0*4kB 2*8kB (UE) 2*16kB (UE) 1*32kB (E) 1*64kB (E) 1*128kB (E) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 272kB
[ 0.689760] Node 0 DMA32: 2*4kB (UM) 1*8kB (M) 4*16kB (UME) 2*32kB (ME) 2*64kB (UE) 4*128kB (UME) 1*256kB (M) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 1040kB
[ 0.691766] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[ 0.693595] 13732 total pagecache pages
[ 0.694107] 0 pages in swap cache
[ 0.694549] Swap cache stats: add 0, delete 0, find 0/0
[ 0.695231] Free swap = 0kB
[ 0.695598] Total swap = 0kB
[ 0.695963] 32763 pages RAM
[ 0.696326] 0 pages HighMem/MovableOnly
[ 0.696880] 15313 pages reserved
[ 0.697287] 0 pages cma reserved
[ 0.697692] 0 pages hwpoisoned
[ 0.698076] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
[ 0.699241] Kernel panic - not syncing: Out of memory and no killable processes...
[ 0.699241]
[ 0.700322] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.15.0-15-generic #16-Ubuntu
[ 0.700322] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 0.700322] Call Trace:
[ 0.700322] dump_stack+0x63/0x8b
[ 0.700322] panic+0xe4/0x244
[ 0.700322] ? dump_header+0x18e/0x285
[ 0.700322] out_of_memory+0x3df/0x4f0
[ 0.700322] __alloc_pages_slowpath+0xa93/0xe60
[ 0.700322] __alloc_pages_nodemask+0x263/0x280
[ 0.700322] alloc_page_interleave+0x17/0x70
[ 0.700322] ? __next_node_in+0x31/0x50
[ 0.700322] alloc_pages_current+0xc8/0xe0
[ 0.700322] __page_cache_alloc+0x81/0xa0
[ 0.700322] pagecache_get_page+0x9b/0x2a0
[ 0.700322] grab_cache_page_write_begin+0x26/0x40
[ 0.700322] simple_write_begin+0x29/0x1b0
[ 0.700322] generic_perform_write+0xb3/0x1b0
[ 0.700322] __generic_file_write_iter+0x1aa/0x1d0
[ 0.700322] generic_file_write_iter+0xe9/0x1f0
[ 0.700322] new_sync_write+0xe7/0x140
[ 0.700322] __vfs_write+0x29/0x40
[ 0.700322] vfs_write+0xb1/0x1a0
[ 0.700322] ? md_run_setup+0x99/0x99
[ 0.700322] SyS_write+0x55/0xc0
[ 0.700322] ? do_name+0x127/0x287
[ 0.700322] xwrite+0x2e/0x61
[ 0.700322] do_copy+0x8f/0xbd
[ 0.700322] write_buffer+0x2b/0x3c
[ 0.700322] flush_buffer+0x39/0x91
[ 0.700322] __gunzip+0x277/0x31b
[ 0.700322] ? bunzip2+0x3be/0x3be
[ 0.700322] ? write_buffer+0x3c/0x3c
[ 0.700322] ? md_run_setup+0x99/0x99
[ 0.700322] ? __gunzip+0x31b/0x31b
[ 0.700322] gunzip+0x11/0x13
[ 0.700322] ? md_run_setup+0x99/0x99
[ 0.700322] unpack_to_rootfs+0x187/0x2c0
[ 0.700322] ? md_run_setup+0x99/0x99
[ 0.700322] ? unpack_to_rootfs+0x2c0/0x2c0
[ 0.700322] ? set_debug_rodata+0x17/0x17
[ 0.700322] populate_rootfs+0x61/0x10f
[ 0.700322] do_one_initcall+0x52/0x19f
[ 0.700322] kernel_init_freeable+0x1af/0x251
[ 0.700322] ? rest_init+0xb0/0xb0
[ 0.700322] kernel_init+0xe/0x100
[ 0.700322] ret_from_fork+0x35/0x40
[ 0.700322] ---[ end Kernel panic - not syncing: Out of memory and no killable processes...
[ 0.700322]

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-crashdump 4.15.0.15.16
ProcVersionSignature: Ubuntu 4.15.0-15.16-generic 4.15.15
Uname: Linux 4.15.0-15-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.15.0-15-generic.
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
Card0.Amixer.info: Error: [Errno 2] No such file or directory: 'amixer': 'amixer'
Card0.Amixer.values: Error: [Errno 2] No such file or directory: 'amixer': 'amixer'
Date: Mon Apr 16 04:15:41 2018
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
Lsusb:
 Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
ProcEnviron:
 TERM=vt220
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcFB: 0 qxldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-15-generic root=UUID=3e45b7ec-412a-11e8-a844-5254003896a5 ro maybe-ubiquity console=ttyS0 crashkernel=384M-:128M
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-15-generic N/A
 linux-backports-modules-4.15.0-15-generic N/A
 linux-firmware 1.173
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.10.2-1ubuntu1
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-artful
dmi.modalias: dmi:bvnSeaBIOS:bvr1.10.2-1ubuntu1:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-artful:cvnQEMU:ct1:cvrpc-i440fx-artful:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-artful
dmi.sys.vendor: QEMU

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[benshushu (benshushu)]

i also see the kdump cannot work on 18.04

[Janghoon-Paul Sim (janghoon)]

kdump is not still working on 18.04.

Kernel : 4.15.0-34-generic
linux-crashdump : 4.15.0.34.36
ubuntu@u-VM-07:~$ cat /var/crash/kexec_cmd
/sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-4.15.0-34-generic root=UUID=51adaf62-9023-4c45-bf94-889906e3d2d2 ro net.ifnames=0 biosdevname=0 nr_cpus=1 systemd.unit=kdump-tools.service irqpoll nousb ata_piix.prefer_ms_hyperv=0" --initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz

If I trigger, the machine gets hold and no response at all.
$echo c > /proc/sysrq-trigger

[Janghoon-Paul Sim (janghoon)]

A console screen when I triggered.

[Guilherme G. Piccoli (gpiccoli)]

I tried here with a Bionic VM (kernel 4.15.0-34) and kdump worked fine, using the default
config (128M reserved for the crash kernel).

I'll try to mimic the HW of Daniel's guest and perhaps the kernel version, although it's super old and seems not available anymore.

@Paul, perhaps worth for you to append "earlyprintk=ttyS0" to your kdump cmdline (assuming ttyS0 is your serial console output) in order to dump some messages while it boots.

Cheers,

Guilherme

[Thadeu Lima de Souza Cascardo (cascardo)]

The OOM seems to be happening during initrd decompression. That has been observed before and also in Cosmic. I want to reduce the initrd footprint in case framebuffer drivers are included, which might happen when cryptsetup or plymouth are installed.

On the other hand, just incrementing the reserved memory for crashkernel will easily fix this.

Cascardo.

[Gaëtan Trellu (goldyfruit)]

I got the same behavior on Xenial with kernel 4.15.0-43-generic.

[ 4.598980] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
[ 4.601946] Kernel panic - not syncing: Out of memory and no killable processes...
[ 4.601946]
[ 4.605054] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.15.0-43-generic #46~16.04.1-Ubuntu
[ 4.605943] Hardware name: HP ProLiant BL460c Gen9, BIOS I36 10/17/2018
[ 4.605943] Call Trace:
[ 4.605943] dump_stack+0x63/0x8b
[ 4.605943] panic+0xe4/0x244
[ 4.60header+0x18f/0x285
[ 4.605943] out_of_memory+0x364/0x4c0
[ 4.605943] __alloc_pages_slowpath+0xda2/0xe90
[ 4.605943] ? radix_tree_extend+0xda/0x160
[ 4.605943] __alloc_pages_nodemask+0x265/0x280
[ 4.605943] alloc_page_interleave+0x17/0x80
[ 4.605943] alloc_pages_current+0xc8/0xe0
[ 4.605943] __page_cache_alloc+0x86/0x90
[ 4.605943] pagecache_get_page+0x88/0x2c0
[ 4.605943] grab_cache_page_write_begin+0x23/0x40
[ 4.605943] simple_write_begin+0x29/0x1b0
[ 4.605943] generic_perform_write+0xba/0x1b0
[ 4.605943] __generic_file_write_iter+0x1a6/0x1f0
[ 4.605943] ? md_run_setup+0x99/0x99
[ 4.605943] generic_file_write_iter+0xf1/0x1d0
[ 4.605943] new_sync_write+0xe5/0x140
[ 4.605943] __vfs_write+0x29/0x40
[ 4.605943] vfs_write+0xb8/0x1b0
[ 4.605943] ? zlib_updatewindow+0x2d/0xd0
[ 4.605943] ? md_run_setup+0x99/0x99
[ 4.605943] SyS_write+0x55/0xc0
[ 4.605943] xwrite+0x2e/0x61
[ 4.605943] do_copy+0x8f/0xbd
[ 4.605943] write_buffer+0x2b/0x3c
[ 4.605943] flush_buffer+0x30/0x8a
[ 4.605943] __gunzip+0x27e/0x322
[ 4.605943] ? bunzip2+0x3a05943] ? write_buffer+0x3c/0x3c
[ 4.605943] ? __gunzip+0x322/0x322
[ 4.605943] gunzip+0x11/0x13
[ 4.605943] ? md_run_setup+0x99/0x99
[ 4.605943] unpack_to_rootfs+0x168/0x2bb
[ 4.605943] ? md_run_setup+0x99/0x99
[ 4.605943] ? unpack_to_rootfs+0x2bb/0x2bb
[ 4.605943] populate_rootfs+0x61/0x10f
[ 4.605943] do_one_initcall+0x55/0x1ac
[ 4.605943] kernel_init_freeable+0x19e/0x238
[ 4.605943] ? rest_init+0xb0/0xb0
[ 4.605943] kernel_init+0xe/0x110
[ 4.605943] ret_from_fork+0x35/0x40
[ 4.605943] ---[ end Kernel panic - not syncing: Out of memory and no killable processes...
[ 4.605943]

[Gaëtan Trellu (goldyfruit)]

By increasing the size reserved to 256MB it's working.

[Guilherme G. Piccoli (gpiccoli)]

OK, so it seems it's really the minimum of reserved memory kernel needs in Bionic that is affecting
the success of kdump here.
Thanks for the report Gaëtan

[C de-Avillez (hggdh2)]

I had two up-to-date Azure instances (16.04 and 18.04) where Linux-crashdump was installed. Both failed, with the following being shown at the end of the serial console:

[ OK ] Started Dispatch Password Requests to Console Directory Watch.
[ OK ] Reached target Local Encrypted Volumes.
[ 18.407975] Out of memory: Kill process 496 (cloud-init) score 127 or sacrifice child
[ 18.417791] Killed process 496 (cloud-init) total-vm:66840kB, anon-rss:12720kB, file-rss:0kB, shmem-rss:0kB
[FAILED] Failed to start Initial cloud-init job (pre-networking).
See 'systemctl status cloud-init-local.service' for details.
[ OK ] Reached target Network (Pre).
         Starting Network Service...
[ OK ] Started Network Service.
[ OK ] Reached target Network.
         Starting Wait for Network to be Configured...
[ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch.
[ 37.269354] Out of memory: Kill process 657 (snap) score 40 or sacrifice child
[ 37.282042] Killed process 657 (snap) total-vm:95160kB, anon-rss:4008kB, file-rss:0kB, shmem-rss:0kB
[* ] (2 of 3) A start job is running for… to be Configured (32s / no limit)[ 47.413761] Out of memory: Kill process 656 (snap) score 41 or sacrifice child
[ 47.422837] Killed process 656 (snap) total-vm:242624kB, anon-rss:4072kB, file-rss:0kB, shmem-rss:0kB
[ OK ] Found device Virtual_Disk 1.
         Starting File System Check on /dev/disk/cloud/azure_resource-part1...
[ *** ] (3 of 3) A start job is running for…re_resource-part1 (44s / no limit)[ 56.870810] Out of memory: Kill process 662 (snap) score 41 or sacrifice child
[ 56.887294] Killed process 662 (snap) total-vm:242880kB, anon-rss:4116kB, file-rss:0kB, shmem-rss:0kB
[ OK ] Started File System Check Daemon to report status.
[ 71.643108] Out of memory: Kill process 660 (snap) score 42 or sacrifice child
[ 71.652187] Killed process 660 (snap) total-vm:242880kB, anon-rss:4220kB, file-rss:0kB, shmem-rss:0kB
[ OK ] Started File System Check on /dev/disk/cloud/azure_resource-part1.
[ TIME ] Timed out waiting for device dev-disk-by\x2dlabel-UEFI.device.
[DEPEND] Dependency failed for /boot/efi.
[DEPEND] Dependency failed for Local File Systems.
[ OK ] Started Emergency Shell.
[ OK ] Reached target Emergency Mode.
[ 114.872426] Out of memory: Kill process 655 (snap) score 49 or sacrifice child
[ 114.881579] Killed process 655 (snap) total-vm:243936kB, anon-rss:4844kB, file-rss:0kB, shmem-rss:0kB
         Starting Tell Plymouth To Write Out Runtime Data...
         Starting Create Volatile Files and Directories...
         Starting AppArmor initialization...
You are in emergency mode. After logging in, type "journalctl -xb" to view
system logs, "systemctl reboot" to reboot, "systemctl default" or "exit"
to boot into default mode.
Press Enter for maintenance
(or press Control-D to continue):

So, no more kernel panics, but
  (1) still no kdump saved;
  (2) the servers end waiting for user intervention (which is quite bad for a cloud instance).

Both servers had a cmdline with "crashkernel=512M-:192M". I edited /etc/default/grub.d/kdump-tools.cfg, changed crashkernel to 256M, and ran update-grub.

Re-tested, an...