Date: Fri, 6 Jun 2003 01:10:40 -0700 From: "David P. Reese Jr." <daver@gomerbud.com> To: current@freebsd.org Subject: LOR: sched lock vs. sio + panic in sched_choose() Message-ID: <20030606081040.GA65780@tombstone.localnet.gomerbud.com>
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I've been getting a lot of these for the last two weeks on my SMP box.
This panic is on -CURRENT from earlier today. Scheduler is ULE.
lock order reversal
1st 0xc047f820 sched lock (sched lock) @ /usr/src/sys/kern/kern_intr.c:548
2nd 0xc04b83c0 sio (sio) @ /usr/src/sys/dev/sio/sio.c:3242
Stack backtrace:
backtrace(c0400378,c04b83c0,c0463120,c0463120,c041266b) at backtrace+0x17
witness_lock(c04b83c0,8,c041266b,caa,c11efc00) at witness_lock+0x697
_mtx_lock_spin_flags(c04b83c0,0,c041266b,caa,0) at _mtx_lock_spin_flags+0xd1
siocnputc(c0463280,d,5,d1d62b68,0) at siocnputc+0x81
cnputc(a,ffffffff,1,c0415c53,c) at cnputc+0x56
putchar(a,d1d62b68,d1d62ab4,c0491d40,0) at putchar+0xcd
kvprintf(c0415c52,c025eba0,d1d62b68,a,d1d62b88) at kvprintf+0x7d
printf(c0415c52,c,c0415a4d,c03fe55b,c0489b20) at printf+0x57
trap_fatal(d1d62c14,38,d1d62bf0,c0236c9d,38) at trap_fatal+0x76
trap(d1d60018,c0240010,c0470010,c11dcbe0,c0482280) at trap+0x123
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc0253ec7, esp = 0xd1d62c54, ebp = 0xd1d62c68 ---
sched_choose(c11dee40,c03fe7a6,28c,0,c11db668) at sched_choose+0x77
choosethread(c11dcbe0,2,c03fdb89,1dc,b6e81bd0) at choosethread+0x36
mi_switch(c047f820,0,c03fb1fd,224,c11db5ac) at mi_switch+0x200
ithread_loop(c11da180,d1d62d48,c03fb0ae,30c,55ff44fd) at ithread_loop+0x256
fork_exit(c022caf0,c11da180,d1d62d48) at fork_exit+0xc0
fork_trampoline() at fork_trampoline+0x1a
--- trap 0x1, eip = 0, esp = 0xd1d62d7c, ebp = 0 ---
Fatal trap 12: page fault while in kernel mode
cpuid = 1; lapic.id = 01000000
fault virtual address = 0x38
fault code = supervisor read, page not present
instruction pointer = 0x8:0xc0253ec7
stack pointer = 0x10:0xd1d62c54
frame pointer = 0x10:0xd1d62c68
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 = 14 (swi7: tty:sio clock)
kernel: type 12 trap, code=0
Stopped at sched_choose+0x77: movl 0x38(%eax),%eax
I recall most if not all of these panics occuring when swi7: tty:sio clock
is the current process. These are not completely repeatable, but if I
simply reboot a couple of times, I can get the panic to occur while the
rc scripts are being run.
--
David P. Reese Jr. daver@gomerbud.com
--------------------------------------------------------------------------
It can be argued that returning a NULL pointer when asked to allocate
zero bytes is a silly response to a silly question.
-- FreeBSD manual page for malloc(3)
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