page fault in fill_kinfo_proc()

[Johannes Hofmann <johannes.hofmann@xxxxxx>]

Hi,

I got the following panic twice after the system was running for some
time. This is with kernel v2.7.3.596.g53d77-DEVELOPMENT.

Fatal trap 12: page fault while in kernel mode
fault virtual address= 0x4b1
fault code= supervisor read, page not present
instruction pointer= 0x8:0xc01a47e8
stack pointer        = 0x10:0xd8479620
frame pointer        = 0x10:0xd8479634
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= 4168 (ps)
current thread          = pri 6 

trap number= 12
panic: page fault
Trace beginning at frame 0xd847952c
panic(ffffffff) at panic+0x8e
panic(c0395e40,c03aba01,0,0,fffff) at panic+0x8e
trap_fatal(4b1,0,d3db7670,d858f590,c) at trap_fatal+0x2da
trap_pfault(6,1,4,d858f590,d3ce41d0) at trap_pfault+0xfd
trap(d84795d8) at trap+0x3eb
calltrap() at calltrap+0xd
--- trap 0, eip = 0, esp = 0xd847961c, ebp = 0xd3d1a1e0 ---
(null)(0,0,6bba7eff,0,0) at 0
Uptime: 2h43m13s
Physical memory: 1530 MB
Dumping 247 MB: (CTRL-C to abort)  (CTRL-C to abort)  232 (CTRL-C to
abort)  216 (CTRL-C to abort)  200 (CTRL-C to abort)  (CTRL-C to
abort)  184 (CTRL-C to abort)  168 152 136 120 104 88 72 56 40 24 8

Reading symbols from /boot/modules/dsched_fq.ko...done.
Loaded symbols for /boot/modules/dsched_fq.ko
Reading symbols from /boot/modules/acpi.ko...done.
Loaded symbols for /boot/modules/acpi.ko
Reading symbols from /boot/modules/ipfw.ko...done.
Loaded symbols for /boot/modules/ipfw.ko
Reading symbols from /boot/modules/linux.ko...done.
Loaded symbols for /boot/modules/linux.ko
Reading symbols from /boot/modules/radeon.ko...done.
Loaded symbols for /boot/modules/radeon.ko
Reading symbols from /boot/modules/drm.ko...done.
Loaded symbols for /boot/modules/drm.ko
Reading symbols from /boot/modules/if_iwi.ko...done.
Loaded symbols for /boot/modules/if_iwi.ko
Reading symbols from /boot/modules/iwi_bss.ko...done.
Loaded symbols for /boot/modules/iwi_bss.ko
_get_mycpu (di=0xc0426760) at ./machine/thread.h:83
83    __asm ("movl %%fs:globaldata,%0" : "=r" (gd) :
"m"(__mycpu__dummy));
(kgdb) bt
#0  _get_mycpu (di=0xc0426760) at ./machine/thread.h:83
#1  md_dumpsys (di=0xc0426760) at
/hammer/usr/src/sys/platform/pc32/i386/dump_machdep.c:263
#2  0xc01afc61 in dumpsys () at
/hammer/usr/src/sys/kern/kern_shutdown.c:839
#3  0xc01b01dc in boot (howto=260) at
/hammer/usr/src/sys/kern/kern_shutdown.c:388
#4  0xc01b0302 in panic (fmt=0xc0395e40 "%s") at
/hammer/usr/src/sys/kern/kern_shutdown.c:745
#5  0xc03619fb in trap_fatal (frame=0xd84795d8, eva=<value optimized out>)
    at /hammer/usr/src/sys/platform/pc32/i386/trap.c:1125
#6  0xc0361b0a in trap_pfault (frame=0xd84795d8, usermode=0, eva=1201)
at /hammer/usr/src/sys/platform/pc32/i386/trap.c:1026
#7  0xc0361fbe in trap (frame=0xd84795d8) at
/hammer/usr/src/sys/platform/pc32/i386/trap.c:713
#8  0xc03512e7 in calltrap () at
/hammer/usr/src/sys/platform/pc32/i386/exception.s:785
#9  0xc01a47e8 in fill_kinfo_proc (p=0xd3ce14d0, kp=0xd8479654) at
/hammer/usr/src/sys/kern/kern_kinfo.c:131
#10 0xc01a8f1b in sysctl_out_proc (p=0xd3ce14d0, req=0xd8479c00,
flags=0) at /hammer/usr/src/sys/kern/kern_proc.c:725
#11 0xc01a9e15 in sysctl_kern_proc (oidp=0xc03e6f20, arg1=0x0, arg2=0,
req=0xd8479c00)
    at /hammer/usr/src/sys/kern/kern_proc.c:860
#12 0xc01c0552 in sysctl_root (oidp=<value optimized out>, arg1=<value
optimized out>, arg2=3, req=0xd8479c00)
    at /hammer/usr/src/sys/kern/kern_sysctl.c:1202
#13 0xc01c063a in userland_sysctl (name=0xd8479c88, namelen=3,
old=0x0, oldlenp=0xbfbfeb54, inkernel=0, new=0x0, newlen=0, 
    retval=0xd8479c84) at /hammer/usr/src/sys/kern/kern_sysctl.c:1284
#14 0xc01c0805 in sys___sysctl (uap=0xd8479cf0) at
/hammer/usr/src/sys/kern/kern_sysctl.c:1224
#15 0xc036254f in syscall2 (frame=0xd8479d40) at
/hammer/usr/src/sys/platform/pc32/i386/trap.c:1319
#16 0xc0351396 in Xint0x80_syscall () at
/hammer/usr/src/sys/platform/pc32/i386/exception.s:876
#17 0x0000001f in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
(kgdb) frame 9
#9  0xc01a47e8 in fill_kinfo_proc (p=0xd3ce14d0, kp=0xd8479654) at
/hammer/usr/src/sys/kern/kern_kinfo.c:131
131if (sess->s_ttyp->t_pgrp != NULL)
(kgdb) p sess->s_ttyp->t_pgrp
$1 = (struct pgrp *) 0x49d
(kgdb) p sess->s_ttyp->t_state
$2 = 436
(kgdb)