Bug 244852

Description Juraj Lutter 2020-03-16 20:00:54 UTC

Hi,

after a call to "sysctl -a | grep maxconn", the box panicked with:

Mar 16 20:53:28 one kernel: Fatal trap 12: page fault while in kernel mode
Mar 16 20:53:28 one kernel: cpuid = 6; apic id = 06
Mar 16 20:53:28 one kernel: fault virtual address       = 0x6fb0076
Mar 16 20:53:28 one kernel: fault code          = supervisor read data, page not present
Mar 16 20:53:28 one kernel: instruction pointer = 0x20:0xffffffff80e07200
Mar 16 20:53:28 one kernel: stack pointer               = 0x28:0xfffffe0c58ad1830
Mar 16 20:53:28 one kernel: frame pointer               = 0x28:0xfffffe0c58ad18a0
Mar 16 20:53:28 one kernel: code segment                = base rx0, limit 0xfffff, type 0x1b
Mar 16 20:53:28 one kernel:                     = DPL 0, pres 1, long 1, def32 0, gran 1
Mar 16 20:53:28 one kernel: processor eflags    = interrupt enabled, resume, IOPL = 0
Mar 16 20:53:28 one kernel: current process             = 64224 (sysctl)
Mar 16 20:53:28 one kernel: trap number         = 12
Mar 16 20:53:28 one kernel: panic: page fault
Mar 16 20:53:28 one kernel: cpuid = 6
Mar 16 20:53:28 one kernel: KDB: stack backtrace:
Mar 16 20:53:28 one kernel: #0 0xffffffff80b4c437 at kdb_backtrace+0x67
Mar 16 20:53:28 one kernel: #1 0xffffffff80b0544e at vpanic+0x17e
Mar 16 20:53:28 one kernel: #2 0xffffffff80b052c3 at panic+0x43
Mar 16 20:53:28 one kernel: #3 0xffffffff80f895c9 at trap_fatal+0x369
Mar 16 20:53:28 one kernel: #4 0xffffffff80f89629 at trap_pfault+0x49
Mar 16 20:53:28 one kernel: #5 0xffffffff80f88cad at trap+0x29d
Mar 16 20:53:28 one kernel: #6 0xffffffff80f68d7c at calltrap+0x8
Mar 16 20:53:28 one kernel: #7 0xffffffff80b128bb at sysctl_root_handler_locked+0x8b
Mar 16 20:53:28 one kernel: #8 0xffffffff80b12112 at sysctl_root+0x1f2
Mar 16 20:53:28 one kernel: #9 0xffffffff80b12636 at userland_sysctl+0x136
Mar 16 20:53:28 one kernel: #10 0xffffffff80b124bf at sys___sysctl+0x5f
Mar 16 20:53:28 one kernel: #11 0xffffffff80f8a6c6 at amd64_syscall+0xa86
Mar 16 20:53:28 one kernel: #12 0xffffffff80f6965d at fast_syscall_common+0x101

How can this be tracked to the root cause? This is a production box and I can't afford to do extensive debugging, unfortunately.

Thanks a lot.