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

Paul Collins
2005-10-29T17:30:17Z

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

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