Re: Oops with PREEMPT-RT on

From: Scott Wood
Date: Mon May 19 2008 - 15:29:21 EST

Rune Torgersen wrote:
Hi I get the following oops when trying to boot a arch/powerpc kernel with
preempt-rt installed (v2.6.25.4-rt1)
The board is using a Freescale 8280 as the main CPU and a Silicon Image
SII3124 SATA controller. The oops seems to happen on fileaccess right
after init starts.
NIP [c0249618] rt_spin_lock_slowlock+0x9c/0x200
LR [c02495ec] rt_spin_lock_slowlock+0x70/0x200
Call Trace:
[ef29d600] [c02495ec] rt_spin_lock_slowlock+0x70/0x200 (unreliable)
[ef29d670] [c00277d0] lock_timer_base+0x2c/0x64
[ef29d690] [c00285e8] del_timer+0x2c/0x78
[ef29d6b0] [c019d108] scsi_delete_timer+0x1c/0x3c
[ef29d6d0] [c01992d0] scsi_done+0x18/0x4c
[ef29d6f0] [c01b19dc] ata_scsi_qc_complete+0x364/0x380
[ef29d720] [c01a8708] __ata_qc_complete+0xd8/0xec
[ef29d740] [c01b011c] ata_qc_complete_multiple+0xc4/0xec
[ef29d760] [c01bcaf4] sil24_interrupt+0x46c/0x52c
[ef29d7a0] [c0048954] handle_IRQ_event+0x64/0x100
[ef29d7d0] [c0048b30] __do_IRQ+0x140/0x1bc
[ef29d7f0] [c00166c4] apmax_int_irq_demux+0x8c/0xb0
[ef29d810] [c0006448] do_IRQ+0x68/0xa8
[ef29d820] [c0010388] ret_from_except+0x0/0x14
--- Exception: 501 at __spin_unlock_irqrestore+0x28/0x4c
LR = __spin_unlock_irqrestore+0x20/0x4c
[ef29d8f0] [c0249600] rt_spin_lock_slowlock+0x84/0x200
[ef29d960] [c00277d0] lock_timer_base+0x2c/0x64

You're recursively entering lock_timer_base, which does a spin_lock_irqsave(). Either interrupts are enabled when they should not be, or an interrupt was supposed to be threaded that isn't.

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