Date: Wed, 14 Jul 2004 17:06:33 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: FreeBSD-gnats-submit@FreeBSD.org Cc: phk@FreeBSD.org Subject: kern/69066: nmdm page fault when slattach on a null modem device Message-ID: <200407142106.i6EL6XWL064669@fledge.watson.org> Resent-Message-ID: <200407142110.i6ELANwr029299@freefall.freebsd.org>
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>Number: 69066 >Category: kern >Synopsis: nmdm page fault when slattach on a null modem device >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Jul 14 21:10:23 GMT 2004 >Closed-Date: >Last-Modified: >Originator: Robert Watson >Release: FreeBSD 5-CURRENT i386 >Organization: - >Environment: Using CVS HEAD kernel from around 20040714. nmdm compiled into the kernel or loaded in a module. >Description: hippy# slattach /dev/nmdm0A /var/run/slattach.nmdm0A.pid hippy# hippy Fatal trap 12: page fault while in kernel mode cpuid = 1; apic id = 01 fault virtual address = 0x0 fault code = supervisor read, page not present instruction pointer = 0x8:0xc054e4a5 stack pointer = 0x10:0xdb0e9cac frame pointer = 0x10:0xdb0e9cb4 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 = 47 (swi6:+) [thread 100026] Stopped at nmdm_task_tty+0x11: movl 0(%eax),%ebx db> trace nmdm_task_tty(c26f4c00,2,c22f8958,0,c07d310a) at nmdm_task_tty+0x11 taskqueue_run(c22f8940,db0e9d1c,c05de75c,0,0) at taskqueue_run+0x83 taskqueue_swi_giant_run(0) at taskqueue_swi_giant_run+0xe ithread_loop(c2308980,db0e9d48,c2308980,c05de628,0) at ithread_loop+0x134 fork_exit(c05de628,c2308980,db0e9d48) at fork_exit+0x98 fork_trampoline() at fork_trampoline+0x8 --- trap 0x1, eip = 0, esp = 0xdb0e9d7c, ebp = 0 --- (kgdb) l *nmdm_task_tty+0x11 0xc054e3e5 is in nmdm_task_tty (../../../dev/nmdm/nmdm.c:153). 148 struct softpart *sp; 149 int c; 150 151 tp = arg; 152 sp = tp->t_sc; 153 otp = sp->other->nm_tty; 154 KASSERT(otp != NULL, ("NULL otp in nmdmstart")); 155 KASSERT(otp != tp, ("NULL otp == tp nmdmstart")); 156 if (sp->other->nm_dcd) { 157 if (!(tp->t_state & TS_ISOPEN)) { Looks like sp->other is NULL. >How-To-Repeat: slattach on a null modem device seems to repeat this quite easily. It sounds a bit like a race in start up or tear-down. >Fix: Not included. >Release-Note: >Audit-Trail: >Unformatted:
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