Date: Thu, 4 Feb 2021 14:31:38 -0700 From: Alan Somers <asomers@freebsd.org> To: FreeBSD Stable ML <stable@freebsd.org> Subject: Page fault in _mca_init during startup Message-ID: <CAOtMX2imwP3x-8LBKGFvMJ%2BjuD%2BsH_02yzs9XvMcCHY=jJs86A@mail.gmail.com>
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After upgrading a machine to FreeBSD, 12.2, it hit the following panic on its first reboot. I suspect that a few other servers have hit this too, but since it happens before swap is mounted there are no core dumps, and they usually reboot immediately. The code in question hasn't changed since 2018. The panic happened in cmci_monitor at line 930. Does anybody have any suggestions for how I could debug further? I can't readily reproduce it, and I can't dump core, but I'd like to investigate it any way I can. The server in question has dual Xeon Gold 6142 CPUs. if (!(ctl & MC_CTL2_CMCI_EN)) /* This bank does not support CMCI. */ return; cc = &cmc_state[PCPU_GET(cpuid)][i]; // <- panic here /* Determine maximum threshold. */ Fatal trap 12: page fault while in kernel mode cpuid = 26; apic id = 34 fault virtual address = 0xd0 fault code = supervisor read data, page not present instruction pointer = 0x20:0xffffffff8125a009 stack pointer = 0x28:0xfffffe0000b65f20 frame pointer = 0x28:0xfffffe0000b65f50 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = resume, IOPL = 0 current process = 11 (idle: cpu26) trap number = 12 panic: page fault cpuid = 26 time = 1 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0000b65be0 vpanic() at vpanic+0x17b/frame 0xfffffe0000b65c30 panic() at panic+0x43/frame 0xfffffe0000b65c90 trap_fatal() at trap_fatal+0x391/frame 0xfffffe0000b65cf0 trap_pfault() at trap_pfault+0x4f/frame 0xfffffe0000b65d40 trap() at trap+0x286/frame 0xfffffe0000b65e50 calltrap() at calltrap+0x8/frame 0xfffffe0000b65e50 --- trap 0xc, rip = 0xffffffff8125a009, rsp = 0xfffffe0000b65f20, rbp = 0xfffffe0000b65f50 --- _mca_init() at _mca_init+0x5d9/frame 0xfffffe0000b65f50 init_secondary_tail() at init_secondary_tail+0xfd/frame 0xfffffe0000b65f80 init_secondary() at init_secondary+0x2d1/frame 0xfffffe0000b65ff0 KDB: enter: panic [ thread pid 11 tid 100029 ] Stopped at kdb_enter+0x37: movq $0,0x12bc1f6(%rip)
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