kern/163540: SCHED_4BSD seems unstable on RELENG_9

[Volodymyr Kostyrko]

>Number:         163540
>Category:       kern
>Synopsis:       SCHED_4BSD seems unstable on RELENG_9
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Dec 22 15:30:11 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Volodymyr Kostyrko
>Release:        RELENG_9
>Organization:
>Environment:
FreeBSD green.tandem.local 9.0-PRERELEASE FreeBSD 9.0-PRERELEASE #0: Thu Dec 22 15:46:04 EET 2011     arcade at green.tandem.local:/usr/obj/usr/src/sys/MINIMAL_4BSD  amd64
>Description:
Recently tried to switch to SCHED_4BSD for testing purposes. After that system starts to dump core from time to time.
>How-To-Repeat:
Compile a kernel with SCHED_4BSD, then sysctl -a for me throws:

Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0xf
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff8038cd3f
stack pointer           = 0x28:0xffffff80d7e48700
frame pointer           = 0x28:0xffffff80d7e48770
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 2030 (sysctl)
trap number             = 12
panic: page fault
cpuid = 1
KDB: stack backtrace:
#0 0xffffffff803b2198 at kdb_backtrace+0x58
#1 0xffffffff80381f40 at panic+0x190
#2 0xffffffff8058ee55 at trap_fatal+0x395
#3 0xffffffff8058f029 at trap_pfault+0x1c9
#4 0xffffffff8058e876 at trap+0x3a6
#5 0xffffffff80579943 at calltrap+0x8
#6 0xffffffff8038cd11 at sysctl_sysctl_next_ls+0x71
#7 0xffffffff8038cd11 at sysctl_sysctl_next_ls+0x71
#8 0xffffffff8038cd11 at sysctl_sysctl_next_ls+0x71
#9 0xffffffff8038cc43 at sysctl_sysctl_next+0x83
#10 0xffffffff8038bf41 at sysctl_root+0x211
#11 0xffffffff8038c508 at userland_sysctl+0x1d8
#12 0xffffffff8038c2f4 at sys___sysctl+0x74
#13 0xffffffff8058f505 at amd64_syscall+0x2a5
#14 0xffffffff80579c2b at Xfast_syscall+0xfb

(kgdb) bt
#0  sched_switch (td=Variable "td" is not available.
) at /usr/src/sys/kern/sched_4bsd.c:1021
#1  0xffffffff80389c94 in mi_switch (flags=dwarf2_read_address: Corrupted DWARF expression.
) at /usr/src/sys/kern/kern_synch.c:448
#2  0xffffffff803bc8ca in sleepq_timedwait (wchan=dwarf2_read_address: Corrupted DWARF expression.
) at /usr/src/sys/kern/subr_sleepqueue.c:652
#3  0xffffffff80389846 in _sleep (ident=Variable "ident" is not available.
) at /usr/src/sys/kern/kern_synch.c:230
#4  0xffffffff8055ed29 in scheduler (dummy=dwarf2_read_address: Corrupted DWARF expression.
) at /usr/src/sys/vm/vm_glue.c:793
#5  0xffffffff803394c3 in mi_startup () at /usr/src/sys/kern/init_main.c:258
#6  0xffffffff8025c93c in btext ()
#7  0xffffffff808e0aa0 in sleepq_chains ()
#8  0xfffffe0006b14440 in ?? ()
#9  0x0000000000000000 in ?? ()
#10 0x0000000000000000 in ?? ()
#11 0xffffffff81ef0bb0 in ?? ()
#12 0xffffffff81ef0b68 in ?? ()
#13 0xffffffff80929890 in bootverbose ()
#14 0xffffffff803a5345 in sched_switch (td=Variable "td" is not available.
) at /usr/src/sys/kern/sched_4bsd.c:1001
Current language:  auto; currently minimal
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: