I am running FreeBSD 12.1 with the latest update on a vmware vSphere virtual machine. The server is a web server running nginx, uwsgi and mariadb. Twice this morning the machine has had a kernel page fault and dumped core. The message was as follows: Jun 26 12:58:41 ws-ag-au-17 kernel: Fatal trap 12: page fault while in kernel mode Jun 26 12:58:41 ws-ag-au-17 kernel: cpuid = 1; apic id = 02 Jun 26 12:58:41 ws-ag-au-17 kernel: fault virtual address = 0x8 Jun 26 12:58:41 ws-ag-au-17 kernel: fault code = supervisor read data, page not present Jun 26 12:58:41 ws-ag-au-17 kernel: instruction pointer = 0x20:0xffffffff80c658e0 Jun 26 12:58:41 ws-ag-au-17 kernel: stack pointer = 0x28:0xfffffe00005cf7a0 Jun 26 12:58:41 ws-ag-au-17 kernel: frame pointer = 0x28:0xfffffe00005cf7d0 Jun 26 12:58:41 ws-ag-au-17 kernel: code segment = base rx0, limit 0xfffff, type 0x1b Jun 26 12:58:41 ws-ag-au-17 kernel: = DPL 0, pres 1, long 1, def32 0, gran 1 Jun 26 12:58:41 ws-ag-au-17 kernel: processor eflags = interrupt enabled, resume, IOPL = 0 Jun 26 12:58:41 ws-ag-au-17 kernel: current process = 1330 (nginx) Jun 26 12:58:41 ws-ag-au-17 kernel: trap number = 12 Jun 26 12:58:41 ws-ag-au-17 kernel: panic: page fault Jun 26 12:58:41 ws-ag-au-17 kernel: cpuid = 1 Jun 26 12:58:41 ws-ag-au-17 kernel: time = 1593140291 Jun 26 12:58:41 ws-ag-au-17 kernel: KDB: stack backtrace: Jun 26 12:58:41 ws-ag-au-17 kernel: #0 0xffffffff80c1d297 at kdb_backtrace+0x67 Jun 26 12:58:41 ws-ag-au-17 kernel: #1 0xffffffff80bd05cd at vpanic+0x19d Jun 26 12:58:41 ws-ag-au-17 kernel: #2 0xffffffff80bd0423 at panic+0x43 Jun 26 12:58:41 ws-ag-au-17 kernel: #3 0xffffffff810a7dcc at trap_fatal+0x39c Jun 26 12:58:41 ws-ag-au-17 kernel: #4 0xffffffff810a7e19 at trap_pfault+0x49 Jun 26 12:58:41 ws-ag-au-17 kernel: #5 0xffffffff810a740f at trap+0x29f Jun 26 12:58:41 ws-ag-au-17 kernel: #6 0xffffffff81081a0c at calltrap+0x8 Jun 26 12:58:41 ws-ag-au-17 kernel: #7 0xffffffff80c64a01 at sbdestroy+0x41 Jun 26 12:58:41 ws-ag-au-17 kernel: #8 0xffffffff80c67225 at sofree+0x275 Jun 26 12:58:41 ws-ag-au-17 kernel: #9 0xffffffff80c67d77 at soclose+0x2f7 Jun 26 12:58:41 ws-ag-au-17 kernel: #10 0xffffffff80b7802a at _fdrop+0x1a Jun 26 12:58:41 ws-ag-au-17 kernel: #11 0xffffffff80b7b151 at closef+0x241 Jun 26 12:58:41 ws-ag-au-17 kernel: #12 0xffffffff80b78547 at closefp+0x97 Jun 26 12:58:41 ws-ag-au-17 kernel: #13 0xffffffff810a8984 at amd64_syscall+0x364 Jun 26 12:58:41 ws-ag-au-17 kernel: #14 0xffffffff81082330 at fast_syscall_common+0x101 Jun 26 12:58:41 ws-ag-au-17 kernel: Uptime: 1h33m41s Jun 26 12:58:41 ws-ag-au-17 kernel: Dumping 274 out of 4057 MB:..6%..12%..24%..36%..41%..53%..65%..71%..82%..94% Jun 26 12:58:41 ws-ag-au-17 kernel: Dump complete I have just enabled the writing of core dumps to disk and will post the dump when it happens again. The web server is usually being accessed when the panic occurs, but only lightly (maximum of two users at once). Memory usage is 500Mb out of 4GB and the dual core CPU does not seem to get above 10% while serving pages. At this point I cannot deliberately reproduce the bug as it seems to be spurious.
Created attachment 215950 [details] core.txt
Created attachment 215951 [details] info.0
Disabling the swap partition stops the constant page faults.
Page faults happen at a lower rate with swap turned off. Possibly related to: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237568 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=241162 As I am using nginx with uwsgi/sendfile.
Also possibly related to this issue, which had been patched: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222259