Jun,
Thanks alot. ' Will implement the prescribed debugging code and see
what it yields...
Jack
> -----Original Message-----
> From: Jun Sun [mailto:jsun@mvista.com]
> Sent: Friday, July 18, 2003 11:30 AM
> To: Jack Miller
> Cc: Linux-Mips; jsun@mvista.com
> Subject: Re: kernel BUG at sched.c:784!
>
>
> On Fri, Jul 18, 2003 at 10:48:22AM -0700, Jack Miller wrote:
> > Jun,
> > Here is the excerpt from sched.c:
> >
> > prepare_to_switch();
> > {
> > struct mm_struct *mm = next->mm;
> > struct mm_struct *oldmm = prev->active_mm;
> > if (!mm) {
> > 784 if (next->active_mm) BUG();
> > next->active_mm = oldmm;
> > atomic_inc(&oldmm->mm_count);
> > enter_lazy_tlb(oldmm, next, this_cpu);
> >
> > Jack
> >
>
> Jack,
>
> Plese change that line to
> if (next->active_mm) {
> printk("active_mm = %p\n", next->active_mm);
> BUG();
> }
>
> If you see next->active_mm to be NULL, you are seeing the CPU bug.
>
> However, given the frequency you are seeing the problem, I suspect it
> is something else.
>
> Whenever CPU runs out active processes to run, it will switch to idle
> process, which does not have a mm. The BUG() basically says "last time
> when idle process was switched off, its active_mm pointer should be set
> NULL". The dropping active_mm code is shortly after the above chunk.
>
> Jun
>
> > > -----Original Message-----
> > > From: Jun Sun [mailto:jsun@mvista.com]
> > > Sent: Friday, July 18, 2003 10:45 AM
> > > To: Jack Miller
> > > Cc: Linux-Mips; jsun@mvista.com
> > > Subject: Re: kernel BUG at sched.c:784!
> > >
> > >
> > > On Fri, Jul 18, 2003 at 10:26:59AM -0700, Jack Miller wrote:
> > > > Jun,
> > > > Thanks for your response. Our kernel is actually based upon the
> > > > MontaVista kernel and that workaround is in place.
> > > >
> > > > Jack
> > > >
> > >
> > > Which line is 784? There is another cpu bug which might cause this.
> > >
> > > I checked our sherman source tree and did not find the corresponding
> > > line.
> > >
> > > Jun
> > >
> > > > > -----Original Message-----
> > > > > From: linux-mips-bounce@linux-mips.org
> > > > > [mailto:linux-mips-bounce@linux-mips.org]On Behalf Of Jun Sun
> > > > > Sent: Friday, July 18, 2003 10:23 AM
> > > > > To: Jack Miller
> > > > > Cc: Linux-Mips; jsun@mvista.com
> > > > > Subject: Re: kernel BUG at sched.c:784!
> > > > >
> > > > >
> > > > >
> > > > > Your kernel looks old, and probably don't have the CPU
> bug workaround
> > > > > code at the beginning of vec3 exception handler.
> > > > >
> > > > > NESTED(except_vec3_generic, 0, sp)
> > > > > #if R5432_CP0_INTERRUPT_WAR
> > > > > mfc0 k0, CP0_INDEX
> > > > > #endif
> > > > >
> > > > > Try this.
> > > > >
> > > > > Jun
> > > > >
> > > > > On Fri, Jul 18, 2003 at 09:57:01AM -0700, Jack Miller wrote:
> > > > > > We are developing a system based around a NEC VR5432 CPU
> > > and Broadcom
> > > > > > BCM703X System Controller. When the system is running with
> > > the intended
> > > > > > application and drivers we intermittently experience a kernel
> > > > > OOPS in the
> > > > > > scheduler. Would someone please provide some insight to the
> > > > > following OOPS
> > > > > > ? It appears (with my limited understanding of the
> > > scheduler) that the
> > > > > > scheduler is trying to schedule the 'idle' task. What
> > > > > condition prevails to
> > > > > > cause this to happen ?
> > > > > >
> > > > > > Using a J-TAG Debugger, I "walked" the task list (in both
> > > > > directions) and
> > > > > > everthing appears to be in order.
> > > > > >
> > > > > > Thanks in advance for your help.
> > > > > >
> > > > > > Regards,
> > > > > > Jack
> > > > > >
> > > > > >
> > > > > > Linux version 2.4.17 (jack@saturn) (gcc version 3.2.2
> > > 20030322 (Pioneer
> > > > > > Voyager)) #1 Fri May 30 14:55:32 PDT 2003
> > > > > > ksymoops 2.4.6 on mips 2.4.17. Options used
> > > > > > -v vmlinux (specified)
> > > > > > -k /proc/ksyms (default)
> > > > > > -l /proc/modules (default)
> > > > > > -o /lib/modules/2.4.17/ (default)
> > > > > > -m System.map (specified)
> > > > > > -T 32
> > > > > >
> > > > > > root@stb2073:~# kernel BUG at sched.c:784!
> > > > > > Unable to handle kernel paging request at virtual address
> > > > > 00000000, epc ==
> > > > > > 8001524c, ra == 8001524c
> > > > > > $0 : 00000000 b001f800 0000001b 00000000 ffffff9d 80008000
> > > > > 0000001f 828f4a20
> > > > > > $8 : 00000001 ffffd890 00001890 801cb119 00000000 00000000
> > > > > fffffff9 ffffffff
> > > > > > $16: 00000000 00000000 809ae000 828f4a20 80008000 00000000
> > > > > 80008000 1001ccf8
> > > > > > $24: 0000000a 00000002 809ae000 809afe90
> > > > > 809afe90 8001524c
> > > > > > epc : 8001524c Tainted: P
> > > > > > Using defaults from ksymoops -t elf32-tradbigmips -a mips:3000
> > > > > > Status: b001f803
> > > > > > Cause : 8000c40c
> > > > > > Process pvrd (pid: 331, stackpage=809ae000)
> > > > > > Stack: 8016eda8 8016edc0 00000310 fffffc18 00138f80
> > > 00000002 809afed8
> > > > > > 00000070
> > > > > > 00000000 1001cd00 1001ccfc 809afec8 80014e74
> > > 80014e6c 00000400
> > > > > > 00000200
> > > > > > c008422b 80bd4160 00000000 00000000 00138f80
> > > 809ae000 80014dd4
> > > > > > 2aac2000
> > > > > > 00000000 809aff18 00001807 7edffa50 8002242c
> > > 00000070 00000000
> > > > > > 8016c290
> > > > > > 00000000 00000000 00000000 00989680 7edffa40
> > > 00000000 8000f7c4
> > > > > > 8000f7c4
> > > > > > 00000000 ...
> > > > > > Call Trace: [<8016eda8>] [<8016edc0>] [<80014e74>] [<80014e6c>]
> > > > > [<c008422b>]
> > > > > > [<80014dd4>]
> > > > > > [<8002242c>] [<8016c290>] [<8000f7c4>] [<8000f7c4>]
> > > > > > Code: 24a5edc0 0c0062f7 24060310 <08005485> ae200000
> > > > > 40016000 00000000
> > > > > > 3421001f 3821001e
> > > > > >
> > > > > >
> > > > > > >>RA; 8001524c <schedule+33c/47c>
> > > > > > >>$1; b001f800 <_end+2fe2aea0/3fe2a6a0>
> > > > > > >>$5; 80008000 <init_task_union+0/0>
> > > > > > >>$7; 828f4a20 <_end+27000c0/3fe2a6a0>
> > > > > > >>$11; 801cb119 <printk_buf.4+19/400>
> > > > > > >>$18; 809ae000 <_end+7b96a0/3fe2a6a0>
> > > > > > >>$19; 828f4a20 <_end+27000c0/3fe2a6a0>
> > > > > > >>$20; 80008000 <init_task_union+0/0>
> > > > > > >>$22; 80008000 <init_task_union+0/0>
> > > > > > >>$23; 1001ccf8 <_binary_ramdisk_gz_size+1001a6da/7fffe9e2>
> > > > > > >>$28; 809ae000 <_end+7b96a0/3fe2a6a0>
> > > > > > >>$29; 809afe90 <_end+7bb530/3fe2a6a0>
> > > > > > >>$30; 809afe90 <_end+7bb530/3fe2a6a0>
> > > > > > >>$31; 8001524c <schedule+33c/47c>
> > > > > >
> > > > > > >>PC; 8001524c <schedule+33c/47c> <=====
> > > > > >
> > > > > > Trace; 8016eda8 <mips_io_port_base+d08/1c30>
> > > > > > Trace; 8016edc0 <mips_io_port_base+d20/1c30>
> > > > > > Trace; 80014e74 <schedule_timeout+74/e4>
> > > > > > Trace; 80014e6c <schedule_timeout+6c/e4>
> > > > > > Trace; c008422b <[bcm7030]scard_interrupt+f/340>
> > > > > > Trace; 80014dd4 <process_timeout+0/2c>
> > > > > > Trace; 8002242c <sys_nanosleep+170/1fc>
> > > > > > Trace; 8016c290 <mips_hwi4_dispatch+70/78>
> > > > > > Trace; 8000f7c4 <stack_done+1c/38>
> > > > > > Trace; 8000f7c4 <stack_done+1c/38>
> > > > > >
> > > > > > Code; 80015240 <schedule+330/47c>
> > > > > > 00000000 <_PC>:
> > > > > > Code; 80015240 <schedule+330/47c>
> > > > > > 0: 24a5edc0 addiu a1,a1,-4672
> > > > > > Code; 80015244 <schedule+334/47c>
> > > > > > 4: 0c0062f7 jal 18bdc <_PC+0x18bdc> 8002de1c
> > > > > > <generic_file_direct_IO+294/2d8>
> > > > > > Code; 80015248 <schedule+338/47c>
> > > > > > 8: 24060310 li a2,784
> > > > > > Code; 8001524c <schedule+33c/47c> <=====
> > > > > > c: 08005485 j 15214 <_PC+0x15214> 8002a454
> > > > > <__vma_link+9c/e0>
> > > > > > <=====
> > > > > > Code; 80015250 <schedule+340/47c>
> > > > > > 10: ae200000 sw zero,0(s1)
> > > > > > Code; 80015254 <schedule+344/47c>
> > > > > > 14: 40016000 mfc0 at,$12
> > > > > > Code; 80015258 <schedule+348/47c>
> > > > > > 18: 00000000 nop
> > > > > > Code; 8001525c <schedule+34c/47c>
> > > > > > 1c: 3421001f ori at,at,0x1f
> > > > > > Code; 80015260 <schedule+350/47c>
> > > > > > 20: 3821001e xori at,at,0x1e
> > > > > >
> > > > > >
> > > > > > Jack Miller <jack.miller@pioneer-pdt.com>
> > > > > > Pioneer Digital Technologies, Inc.
> > > > > > 6170 Cornerstone Court East
> > > > > > Suite 330
> > > > > > San Diego, CA 92121-3767
> > > > > > vox: (858)824-0790 x356
> > > > > > fax: (858)824-0796
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
