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Description

This article explains the FPC vmcore dump that happened on the MX platform.

Symptoms

Model: mx10008
Junos: 21.4R3-S6.5

root@MX-RE0> show system core-dumps no-forwarding

-rw-r--r--  1 root  wheel  996977836 Jul 10 08:06 /var/crash/fpc0-vmcore-2026-07-10_07_58_19.tgz

FPC 0            REV 40   xxxxxxxx  xxxxxxx          JNP10K-LC9600

 crash> bt -l
PID: 16903    TASK: ffff8806fd10d4c0  CPU: 14   COMMAND: "AftTimer-0"
#0 [ffffc90004367930] machine_kexec at ffffffff8024bed4
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/include/linux/ftrace.h: 691
#1 [ffffc90004367980] __crash_kexec at ffffffff80312140
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/kernel/kexec_core.c: 900
#2 [ffffc90004367a40] __crash_kexec at ffffffff803121f5
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/kernel/kexec_core.c: 902
#3 [ffffc90004367a58] crash_kexec at ffffffff8031223b
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/include/linux/compiler.h: 248
#4 [ffffc90004367a78] oops_end at ffffffff80220b37
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/kernel/dumpstack.c: 250
#5 [ffffc90004367aa0] no_context at ffffffff8025626c
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/mm/fault.c: 796
#6 [ffffc90004367b00] __bad_area_nosemaphore at ffffffff802565ed
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/mm/fault.c: 883
#7 [ffffc90004367b58] bad_area_nosemaphore at ffffffff80256704
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/mm/fault.c: 890
#8 [ffffc90004367b68] __do_page_fault at ffffffff80256b6f
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/mm/fault.c: 1411
#9 [ffffc90004367bd0] do_page_fault at ffffffff80256f4c
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/mm/fault.c: 1431
#10 [ffffc90004367be0] page_fault at ffffffff80dd34c2
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/entry/entry_64.S: 959
    [exception RIP: copy_page_range+2363]
    RIP: ffffffff803be5ab  RSP: ffffc90004367c90  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: 00007ff0ff200000  RCX: 0000000000000001
    RDX: 0000000080000000  RSI: ffff8807c4b611d0  RDI: 00000000c3d930c0
    RBP: ffffc90004367db0   R8: 0000000000000000   R9: 0000000000000002
    R10: ffff88037c66a000  R11: 0000000000000000  R12: 00007ff0ff200000
    R13: 00007ff0ff200000  R14: 0000000000000020  R15: 00007ff0ff200000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/include/linux/mmu_notifier.h: 288
#11 [ffffc90004367db8] copy_process at ffffffff80289251
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/kernel/fork.c: 623
#12 [ffffc90004367ea8] _do_fork at ffffffff8028a1da
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/kernel/fork.c: 1897
#13 [ffffc90004367f20] sys_clone at ffffffff8028a579
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/kernel/fork.c: 1994
#14 [ffffc90004367f30] do_syscall_64 at ffffffff80202b45
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/entry/common.c: 285
#15 [ffffc90004367f50] entry_SYSCALL_64_after_swapgs at ffffffff80dd24be
    /volume/build/jenkins/workspace/Yocto/production/wrl9/WRL9-build-kernels/daily/tmp/work-shared/re-64b/kernel-source/arch/x86/entry/entry_64.S: 204
    RIP: 00007ff13bc2e7ad  RSP: 00007ff11b1c3ed0  RFLAGS: 00000246
    RAX: ffffffffffffffda  RBX: 0000000000000001  RCX: 00007ff13bc2e7ad
    RDX: 0000000000000000  RSI: 0000000000000000  RDI: 0000000001200011
    RBP: 00007ff11b1c3ef0   R8: 00007ff11b1fe700   R9: 00000000000041ae
    R10: 00007ff11b1fe9d0  R11: 0000000000000246  R12: 0000000000000001
    R13: 0000000000000001  R14: 0000000000004207  R15: 0000000000000008
    ORIG_RAX: 0000000000000038  CS: 0033  SS: 002b

 
 
[27323355.863643] BUG: unable to handle kernel paging request at 000000006eddb0d6
[27323355.870910] IP: [<00000000d1ee108e>] copy_page_range+0x93b/0xac0
[27323355.877197] PGD 75f4a0067 PUD 0 
[27323355.880732] Oops: 0000 [#1] PREEMPT SMP
[27323355.884830] Modules linked in: uio_pci_hostif macvlan 8021q ebtable_filter tpm_rng amd64_edac_mod edac_core crct10dif_pclmul crct10dif_common jnx_pmb_nvram jnx_f1_bcpld jnx_cbios_debugfs k10temp snd_hda_intel snd_hda_codec snd_hda_core i2c_piix4 tmp401 ofpart m25p80 spi_nor max6697 pmbus ucd9000 vt7505 max20751 ltc2945 pmbus_core gpio_supercon_hotswap leds_supercon_ledx jnx_mastership_supercon uio_pdrv_genirq leds_supercon_led2 uio tpm_crb acpi_cpufreq sam_core mtdoops mtd i2c_dev gpio_sam gpio_ptxpmb_cpld
[27323355.930800] CPU: 14 PID: 16903 Comm: AftTimer-0 Not tainted 4.8.28-WR2.2.1_standard-gad6c183 #1
[27323355.939752] Hardware name: Juniper Networks Inc. 0D88/0D7A, BIOS CASN_P_PMB1_00.29.01 09/12/2022
[27323355.948790] task: 0000000094263ba7 task.stack: 000000001dbca715
[27323355.954965] RIP: 0010:[<ffffffff803be5ab>]  [<00000000d1ee108e>] copy_page_range+0x93b/0xac0
[27323355.963678] RSP: 0018:ffffc90004367c90  EFLAGS: 00010246
[27323355.969248] RAX: 0000000000000000 RBX: 00007ff0ff200000 RCX: 0000000000000001
[27323355.976638] RDX: 0000000080000000 RSI: ffff8807c4b611d0 RDI: 00000000c3d930c0
[27323355.984027] RBP: ffffc90004367db0 R08: 0000000000000000 R09: 0000000000000002
[27323355.991419] R10: ffff88037c66a000 R11: 0000000000000000 R12: 00007ff0ff200000
[27323355.998808] R13: 00007ff0ff200000 R14: 0000000000000020 R15: 00007ff0ff200000
[27323356.006198] FS:  00007ff11b1fe700(0000) GS:ffff88087eb80000(0000) knlGS:0000000000000000
[27323356.014542] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[27323356.020544] CR2: 00000000c3d93428 CR3: 00000007a1df2000 CR4: 00000000003406f0
[27323356.027932] Stack:
[27323356.030209]  00007ff0ff1fffff 0000000000000020 00007ff0ff1fffff 00007ff0ee600000
[27323356.037948]  ffff8803757c4800 ffff880379077e20 00007ff0ff200000 ffff8807a1df2800
[27323356.045685]  ffff8806fd66ee20 00007ff0ff200000 ffff8807c3d930c0 00007ff0ff1fffff
[27323356.053425] Call Trace:
[27323356.056139]  [<0000000035ac1e03>] copy_process.part.6+0xd91/0x1b50
[27323356.062579]  [<00000000704c253d>] _do_fork+0xca/0x3c0
[27323356.067889]  [<000000003174c534>] SyS_clone+0x19/0x20
[27323356.073198]  [<00000000c79d53b3>] do_syscall_64+0x65/0xd0
[27323356.078857]  [<00000000e18d5d08>] entry_SYSCALL_64_after_swapgs+0x58/0xc6
[27323356.085901] Code: 68 00 04 00 e0 87 ec ff ff 81 c0 0f 84 d8 00 00 00 48 83 bd e8 fe ff ff 20 b8 f4 ff ff ff 0f 85 60 45 ab 16 40 8b bd 30 ff ff ff <48> 83 bf 68 03 00 00 00 0f 84 fb f7 ff ff 48 8b 95 10 ff ff ff 
[27323356.106480] RIP  [<00000000d1ee108e>] copy_page_range+0x93b/0xac0
[27323356.112853]  RSP <ffffc90004367c90>
[27323356.116604] CR2: 00000000c3d93428

Solution

The FPC experienced a Linux kernel page fault/kernel panic and automatically rebooted.
The issue occurred in aftd-trio while creating a worker thread. The kernel encountered a corrupted memory-table pointer pointing to an invalid address.
The kernel panicked to protect system integrity, generated a vmcore crash dump, and restarted the FPC.
This was a software memory-related event, not a routing protocol, Routing Engine, or hardware failure.
The FPC had been running for a long time, suggesting this was an isolated event rather than a recurring problem.=
If the FPC remains stable after the reboot, it can be treated as a one-time occurrence.

Modification History

2026-07-17 : Article Created