Tejun Heo wrote:
> Please test this one instead.  Thanks.
> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 1c00526..c9999e6 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -5871,6 +5871,7 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
>  	if (!ap)
>  		return NULL;
>  
> +	ap->pflags |= ATA_PFLAG_INITIALIZING;
>  	ap->lock = &host->lock;
>  	ap->flags = ATA_FLAG_DISABLED;
>  	ap->print_id = -1;
> @@ -6239,6 +6240,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
>  			ehi->action |= ATA_EH_SOFTRESET;
>  			ehi->flags |= ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET;
>  
> +			ap->pflags &= ~ATA_PFLAG_INITIALIZING;
>  			ap->pflags |= ATA_PFLAG_LOADING;
>  			ata_port_schedule_eh(ap);
>  
> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> index 59d0fb5..4c6914c 100644
> --- a/drivers/ata/libata-eh.c
> +++ b/drivers/ata/libata-eh.c
> @@ -529,6 +529,9 @@ void ata_port_schedule_eh(struct ata_port *ap)
>  {
>  	WARN_ON(!ap->ops->error_handler);
>  
> +	if (ap->pflags & ATA_PFLAG_INITIALIZING)
> +		return;
> +
>  	ap->pflags |= ATA_PFLAG_EH_PENDING;
>  	scsi_schedule_eh(ap->scsi_host);
>  
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index fa551fd..8ca3611 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -191,6 +191,7 @@ enum {
>  	ATA_PFLAG_LOADING	= (1 << 4), /* boot/loading probe */
>  	ATA_PFLAG_UNLOADING	= (1 << 5), /* module is unloading */
>  	ATA_PFLAG_SCSI_HOTPLUG	= (1 << 6), /* SCSI hotplug scheduled */
> +	ATA_PFLAG_INITIALIZING	= (1 << 7), /* being initialized, don't touch */
>  
>  	ATA_PFLAG_FLUSH_PORT_TASK = (1 << 16), /* flush port task */
>  	ATA_PFLAG_SUSPENDED	= (1 << 17), /* port is suspended (power) */

Okay, while this patch allows my system to boot, it eventually crashed.
 Unfortunately, I don't know enough to know if this crash is at all
related, but it seems like it might be?

[ 1314.960784] irq 316: nobody cared (try booting with the "irqpoll" option)
[ 1314.967602]
[ 1314.967602] Call Trace:
[ 1314.971566]  [<ffffffff8025dae3>] dump_trace+0xb6/0x3d6
[ 1314.976809]  [<ffffffff8025de3f>] show_trace+0x3c/0x52
[ 1314.981963]  [<ffffffff8025de6a>] dump_stack+0x15/0x17
[ 1314.987118]  [<ffffffff802993c8>] __report_bad_irq+0x38/0x7c
[ 1314.992790]  [<ffffffff802995db>] note_interrupt+0x1cf/0x215
[ 1314.998463]  [<ffffffff8029a037>] handle_edge_irq+0x104/0x133
[ 1315.004231]  [<ffffffff8025f4e1>] do_IRQ+0x6d/0xd5
[ 1315.009039]  [<ffffffff80255071>] ret_from_intr+0x0/0xa
[ 1315.014281]  [<ffffffff8024e88b>] mwait_idle+0x46/0x4b
[ 1315.019433]  [<ffffffff802422f4>] cpu_idle+0x87/0xaa
[ 1315.024414]  [<ffffffff8025c988>] rest_init+0x49/0x4b
[ 1315.029489]  [<ffffffff805dca5d>] start_kernel+0x291/0x29c
[ 1315.034989]  [<ffffffff805dc13a>] _sinittext+0x13a/0x141
[ 1315.040323]
[ 1315.041813] handlers:
[ 1315.044090] [<ffffffff803e4951>] (ahci_interrupt+0x0/0x47a)
[ 1315.049722] Disabling IRQ #316
[ 1345.037254] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2
frozen
[ 1345.044333] ata1.00: cmd c8/00:08:ff:53:00/00:00:00:00:00/e2 tag 0
cdb 0x0 data 4096 in
[ 1345.044334]          res 40/00:00:76:5a:00/00:00:00:00:00/e0 Emask
0x4 (timeout)
[ 1345.059832] ata3.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x2
frozen
[ 1345.066919] ata3.00: cmd 60/08:00:bb:26:0a/00:00:09:00:00/40 tag 0
cdb 0x0 data 4096 in
[ 1345.066920]          res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask
0x4 (timeout)
[ 1345.389731] ata1: soft resetting port
[ 1345.396451] ata3: soft resetting port

I've attached the entire dmesg, as well as the output of lspci -nn (but
while running under 2.6.21-rc6-mm2, if that matters).