Re: 2.6.14: Oops on suspend after on-the-fly switch to anticipatory i/o scheduler - PowerBook5,4

Tejun Heo
2005-10-30T03:00:11Z

Hello, Paul.

Paul Collins wrote:
> I boot with elevator=cfq (wanted to try the ionice stuff, never got
> around to it). Having decided to go back to the anticipatory
> scheduler, I did the following:
>
> # echo anticipatory > /sys/block/hda/queue/scheduler
> # echo anticipatory > /sys/block/hdc/queue/scheduler
>
> A while later I did 'sudo snooze', which produced the Oops below.
>
> Booting with elevator=as and then changing to cfq, sleep works fine.
> But if I resume and change back to anticipatory I get a similar Oops
> on the next 'sudo snooze'.
>
>
> Oops: kernel access of bad area, sig: 11 [#1]
> NIP: C01E1948 LR: C01D6A60 SP: EFBC5C20 REGS: efbc5b70 TRAP: 0300 Not tainted
> MSR: 00001032 EE: 0 PR: 0 FP: 0 ME: 1 IR/DR: 11
> DAR: 00000020, DSISR: 40000000
> TASK = efb012c0[1213] 'pmud' THREAD: efbc4000
> Last syscall: 54
> GPR00: 00080000 EFBC5C20 EFB012C0 EFE9E044 EFBC5CE8 00000002 00000000 C03B0000
> GPR08: C046E5D8 00000000 C03B47C8 E6A58360 22042422 1001E4DC 10010000 10000000
> GPR16: 10000000 10000000 10000000 7FE4EB40 10000000 10000000 10010000 C0400000
> GPR24: C0380000 00000002 00000002 C046E0C0 00000000 00000002 00000000 EFBC5CE8
> NIP [c01e1948] as_insert_request+0xa8/0x6b0
> LR [c01d6a60] __elv_add_request+0xa0/0x100
> Call trace:
> [c01d6a60] __elv_add_request+0xa0/0x100
> [c01ffb84] ide_do_drive_cmd+0xb4/0x190
> [c01fc1c0] generic_ide_suspend+0x80/0xa0
> [c01d4574] suspend_device+0x104/0x160
> [c01d47c0] device_suspend+0x120/0x330
> [c03f3b50] pmac_suspend_devices+0x50/0x1b0
> [c03f4294] pmu_ioctl+0x344/0x9b0
> [c0082aa4] do_ioctl+0x84/0x90
> [c0082b3c] vfs_ioctl+0x8c/0x460
> [c0082f50] sys_ioctl+0x40/0x80
> [c0004850] ret_from_syscall+0x0/0x4c
>

Can you please post assembly of as_insert_request? You can get this by
doing 'objdump -d drivers/block/as-iosched.o | less' and copy & pasting
as_insert_request part.

I'm also trying to reproduce the oops but haven't succeeded yet. Does
the oops occur only if the disk is loaded while switching scheduler /
snoozing or does it happen regardless of disk load?

And one more thing. Can you please try the following program and see if
it causes the oops? The program simply writes 3, sleeps one second and
then writes 0. When redirected to the disk's power/state sysfs node, it
will make the disk sleep for 1 second and then wake it up.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
int level = 3;
if (argc > 1)
level = atoi(argv[1]);
setvbuf(stdout, NULL, _IONBF, 0);
printf("%d", level);
sleep(1);
printf("0");
return 0;
}

After compiling, do the following.

./a.out > /sys/block/hd?/device/power/state

Thanks. :-)

--
tejun