panic: page fault in kern_kevent

[Anders Nordby]

Hi,

Just wanted to say that I have the same problem, kernel crashing because
of kernel queues usage in Squid 2.6. I've reported some more information
on:

http://www.freebsd.org/cgi/query-pr.cgi?pr=103127

On Mon, Jul 17, 2006 at 12:20:29AM +0200, Pawel Worach wrote:
> Under moderate kqueue load I caught the following:
> 
> Fatal trap 12: page fault while in kernel mode
> fault virtual address   = 0x0
> fault code              = supervisor read, page not present
> instruction pointer     = 0x20:0x0
> stack pointer           = 0x28:0xe745db78
> frame pointer           = 0x28:0xe745dbb8
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, def32 1, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 582 (squid)
> trap number             = 12
> panic: page fault
> KDB: stack backtrace:
> kdb_backtrace(c065b33b,c06a4780,c065344e,e745da80,100) at kdb_backtrace+0x2e
> panic(c065344e,c066df69,c49c0dd0,1,1) at panic+0xb7
> trap_fatal(e745db38,0,1,0,c05239e2) at trap_fatal+0x33e
> trap_pfault(e745db38,0,0,e745db38,0) at trap_pfault+0x242
> trap(c05e0008,c7310028,28,0,4) at trap+0x350
> calltrap() at calltrap+0x5
> --- trap 0xc, eip = 0, esp = 0xe745db78, ebp = 0xe745dbb8 ---
> MAXCPU(c4b20500,e745dbe8,c65c3300,1,c0c38000) at 0
> kern_kevent(c65c3300,3,5,80,e745dcbc) at kern_kevent+0xf8
> kevent(c65c3300,e745dd04,18,16,c65c3300) at kevent+0x7a
> syscall(821003b,3b,822003b,48106cf0,bfbfeec8) at syscall+0x380
> Xint0x80_syscall() at Xint0x80_syscall+0x1f
> --- syscall (363, FreeBSD ELF32, kevent), eip = 0x4821ccfb, esp = 
> 0xbfbfedfc, ebp = 0xbfbfee48 ---
> Uptime: 3d15h16m7s
> Dumping 1023 MB (2 chunks)
>   chunk 0: 1MB (159 pages) ... ok
>   chunk 1: 1023MB (261884 pages) 1008 992 976 960 944 928 912 896 880 
> 864 848 832 816 800 784 768 752 736 720 704 688 672 656 640 624 608 592 
> 576 560 544 528 512 496 480 464 448 432 416 400 384 368 352 336 320 304 
> 288 272 256 240 224 208 192 176 160 144 128 112 96 80 64 48 32 16
> 
> (kgdb) bt
> #0  doadump () at pcpu.h:165
> #1  0xc04c261c in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:409
> #2  0xc04c299d in panic (fmt=0xc065344e "%s")
>     at /usr/src/sys/kern/kern_shutdown.c:565
> #3  0xc0637f7e in trap_fatal (frame=0xe745db38, eva=0)
>     at /usr/src/sys/i386/i386/trap.c:836
> #4  0xc0637c12 in trap_pfault (frame=0xe745db38, usermode=0, eva=0)
>     at /usr/src/sys/i386/i386/trap.c:744
> #5  0xc0637780 in trap (frame=
>       {tf_fs = -1067581432, tf_es = -953090008, tf_ds = 40, tf_edi = 0, 
> tf_esi = 4, tf_ebp = -414852168, tf_isp = -414852252, tf_ebx = 4, tf_edx 
> = -953052640, tf_ecx = -1066925280, tf_eax = -1066924800, tf_trapno = 
> 12, tf_err = 0, tf_eip = 0, tf_cs = 32, tf_eflags = 66118, tf_esp = 
> -1068903001, tf_ss = -953052640})
>     at /usr/src/sys/i386/i386/trap.c:434
> #6  0xc062498a in calltrap () at /usr/src/sys/i386/i386/exception.s:139
> #7  0x00000000 in ?? ()
> Previous frame inner to this frame (corrupt stack?)
> (kgdb) l *kern_kevent+0xf8
> 0xc049c6d8 is in kern_kevent (/usr/src/sys/kern/kern_event.c:637).
> 632                             goto done;
> 633                     changes = keva;
> 634                     for (i = 0; i < n; i++) {
> 635                             kevp = &changes[i];
> 636                             kevp->flags &= ~EV_SYSFLAGS;
> 637                             error = kqueue_register(kq, kevp, td, 1);
> 638                             if (error) {
> 639                                     if (nevents != 0) {
> 640                                             kevp->flags = EV_ERROR;
> 641                                             kevp->data = error;
> 
> System is i386 UP running FreeBSD 6.1-STABLE #0: Sun Jul  9 01:11:16 
> CEST 2006
> 
> -- 
> Pawel
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-- 
Anders.