Crash with FreeBSD 6.1 STABLE of today

[Martin Blapp]

Hi,

>>> Unfortunaltly I get this with the debug kernel.
>>> Does one have to boot with the debug.kernel itself
>>> to get a trace which is usable ?

Sigh. A recompile helped !

(kgdb) where
#0  doadump () at pcpu.h:165
#1  0xc066355e in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:409
#2  0xc06638b5 in panic (fmt=0xc0891732 "%s") at /usr/src/sys/kern/kern_shutdown.c:565
#3  0xc085c6b6 in trap_fatal (frame=0xed6e4ab8, eva=4) at /usr/src/sys/i386/i386/trap.c:836
#4  0xc085c3bf in trap_pfault (frame=0xed6e4ab8, usermode=0, eva=4) at /usr/src/sys/i386/i386/trap.c:744
#5  0xc085bfb5 in trap (frame=
       {tf_fs = 8, tf_es = 40, tf_ds = -1063714776, tf_edi = -1064042304, tf_esi 
= 0, tf_ebp = -311538944, tf_isp = -311538972, tf_ebx = -967615488, tf_edx = 
-1063651212, tf_ecx = -941099136, tf_eax = 0, tf_trapno = 12, tf_err = 0, tf_eip = -1066845359, tf_cs 
= 32, tf_eflags = 66194, tf_esp = -967615488, tf_ss = 0})
     at /usr/src/sys/i386/i386/trap.c:434
#6  0xc0848bea in calltrap () at /usr/src/sys/i386/i386/exception.s:139
#7  0xc0693b51 in ttymodem (tp=0xc6535c00, flag=-1063651212) at /usr/src/sys/kern/tty.c:1659
#8  0xc0698362 in ptcclose (dev=0x0, flags=3, fmt=8192, td=0xc7e7f780) at linedisc.h:136
#9  0xc0638a6f in giant_close (dev=0xcb3c1100, fflag=3, devtype=8192, td=0xc7e7f780) at /usr/src/sys/kern/kern_conf.c:266
#10 0xc06162bf in devfs_close (ap=0xed6e4b7c) at /usr/src/sys/fs/devfs/devfs_vnops.c:287
#11 0xc086dc1c in VOP_CLOSE_APV (vop=0x0, a=0xc099f874) at vnode_if.c:426
#12 0xc06c87e2 in vn_close (vp=0xc9cdf660, flags=3, file_cred=0x0, td=0xc7e7f780) at vnode_if.h:227
#13 0xc06c974a in vn_closefile (fp=0xc6fc5438, td=0xc7e7f780) at /usr/src/sys/kern/vfs_vnops.c:865
#14 0xc06162e7 in devfs_close_f (fp=0xc6fc5438, td=0xc7e7f780) at /usr/src/sys/fs/devfs/devfs_vnops.c:297
#15 0xc0642cdc in fdrop_locked (fp=0xc6fc5438, td=0xc7e7f780) at file.h:295
#16 0xc0642c29 in fdrop (fp=0xc6fc5438, td=0xc7e7f780) at /usr/src/sys/kern/kern_descrip.c:2122
#17 0xc06411c7 in closef (fp=0xc6fc5438, td=0xc7e7f780) at /usr/src/sys/kern/kern_descrip.c:1942
#18 0xc063e329 in close (td=0xc7e7f780, uap=0x0) at /usr/src/sys/kern/kern_descrip.c:1007
#19 0xc085c9f7 in syscall (frame=
       {tf_fs = 59, tf_es = 59, tf_ds = 59, tf_edi = 0, tf_esi = 673925920, 
tf_ebp = -1077941928, tf_isp = -311538332, tf_ebx = 673852332, tf_edx = 
673925920, tf_ecx = 673925920,
tf_eax = 6, tf_trapno = 12, tf_err = 2, tf_eip = 673354727, tf_cs = 51, 
tf_eflags = 518, tf_esp = -1077941956, tf_ss = 59}) at 
/usr/src/sys/i386/i386/trap.c:981
#20 0xc0848c3f in Xint0x80_syscall () at /usr/src/sys/i386/i386/exception.s:200
#21 0x00000033 in ?? ()
Previous frame inner to this frame (corrupt stack?)
(kgdb)

(kgdb) frame 5
#5  0xc085bfb5 in trap (frame=
       {tf_fs = 8, tf_es = 40, tf_ds = -1063714776, tf_edi = -1064042304, tf_esi 
= 0, tf_ebp = -311538944, tf_isp = -311538972, tf_ebx = -967615488, tf_edx = 
-1063651212, tf_ecx =
  -941099136, tf_eax = 0, tf_trapno = 12, tf_err = 0, tf_eip = -1066845359, tf_cs 
= 32, tf_eflags = 66194, tf_esp = -967615488, tf_ss = 0})
     at /usr/src/sys/i386/i386/trap.c:434

(kgdb) frame 8
#8  0xc0698362 in ptcclose (dev=0x0, flags=3, fmt=8192, td=0xc7e7f780) at 
linedisc.h:136

136             return ((*linesw[tp->t_line]->l_modem)(tp, flag));
(kgdb) list
131
132     static __inline int
133     ttyld_modem(struct tty *tp, int flag)
134     {
135
136             return ((*linesw[tp->t_line]->l_modem)(tp, flag));
137     }
138
139     #endif /* _KERNEL */

(kgdb) frame 7

(kgdb) p *tp->t_session
Cannot access memory at address 0x0

(kgdb) frame 7
#7  0xc0693b51 in ttymodem (tp=0xc6535c00, flag=-1063651212) at /usr/src/sys/kern/tty.c:1659
1659                                    if (tp->t_session->s_leader) {
(kgdb) list
1654                        !ISSET(tp->t_cflag, CLOCAL)) {
1655                            SET(tp->t_state, TS_ZOMBIE);
1656                            CLR(tp->t_state, TS_CONNECTED);
1657                            if (tp->t_session) {
1658                                    sx_slock(&proctree_lock);
1659                                    if (tp->t_session->s_leader) {
1660                                            struct proc *p;
1661
1662                                            p = tp->t_session->s_leader;
1663                                            PROC_LOCK(p);

(kgdb) p *tp->t_session
Cannot access memory at address 0x0

So here the problem is. Why is tp->t_session empty ? Maybe it has been already 
free() earlier and we have some race here ?

Martin