I booted a 3.0 kernel (i686) on a relatively old hardware,
on a server which was running 2.6.32 stable series for a
long while.

And at the first boot I see the following messages in dmesg:

...
[    2.817314] mptbase: ioc0: Initiating bringup
[    3.230016] ioc0: LSI53C1030 B2: Capabilities={Initiator}
[    4.120665] scsi2 : ioc0: LSI53C1030 B2, FwRev=01000e00h, Ports=1, MaxQ=222, IRQ=27
[    4.489143] mptspi 0000:08:07.1: PCI INT B -> GSI 28 (level, low) -> IRQ 28
[    4.489361] mptbase: ioc1: Initiating bringup
[   19.486696] mptbase: ioc0: WARNING - Issuing Reset from mpt_config!!, doorbell=0x24000000
[   20.126685] mptbase: ioc0: Attempting Retry Config request type 0x4, page 0x1, action 2
[   20.126831] mptbase: ioc0: Retry completed ret=0x0 timeleft=4500
[   20.127697] scsi 2:0:0:0: Direct-Access     IBM-ESXS DTN073C3UCDY10FN S25J PQ: 0 ANSI: 3
...
[   22.604075] sd 2:0:3:0: [sdd] Attached SCSI disk
[   22.635177] ------------[ cut here ]------------
[   22.635290] WARNING: at block/genhd.c:1474 __disk_unblock_events+0xe1/0xf0()
[   22.635371] Hardware name: eserver xSeries 345 -[867052G]-
[   22.635448] Modules linked in: mptspi(+) mptscsih mptbase scsi_transport_spi e1000 ohci_hcd pata_serverworks libata usbhid hid usbcore sd_mod scsi_mod crc_t10dif
[   22.636260] Pid: 271, comm: blkid Not tainted 3.0.0-i686 #3.0.23
[   22.636334] Call Trace:
[   22.636407]  [<c1040118>] ? warn_slowpath_common+0x78/0xb0
[   22.636482]  [<c1188d81>] ? __disk_unblock_events+0xe1/0xf0
[   22.636556]  [<c1188d81>] ? __disk_unblock_events+0xe1/0xf0
[   22.636631]  [<c104016b>] ? warn_slowpath_null+0x1b/0x20
[   22.636705]  [<c1188d81>] ? __disk_unblock_events+0xe1/0xf0
[   22.636783]  [<c1124f57>] ? __blkdev_get+0x157/0x3c0
[   22.636856]  [<c1125203>] ? blkdev_get+0x43/0x2b0
[   22.636931]  [<c11616b0>] ? security_dentry_open+0x70/0x80
[   22.637006]  [<c11245f8>] ? bd_acquire+0x28/0xc0
[   22.637080]  [<c10f70c8>] ? __dentry_open+0x118/0x2b0
[   22.637154]  [<c10f7348>] ? nameidata_to_filp+0x68/0x70
[   22.637228]  [<c1125470>] ? blkdev_get+0x2b0/0x2b0
[   22.637302]  [<c110429d>] ? do_last+0xcd/0x820
[   22.637375]  [<c10fa48b>] ? get_empty_filp+0x11b/0x1d0
[   22.637449]  [<c1105601>] ? path_openat+0xa1/0x370
[   22.637523]  [<c11059b4>] ? do_filp_open+0x34/0x90
[   22.637597]  [<c10464c1>] ? irq_exit+0x31/0xa0
[   22.637672]  [<c12e69d2>] ? call_function_interrupt+0x2a/0x30
[   22.637746]  [<c10f6cce>] ? do_sys_open+0xee/0x1c0
[   22.637820]  [<c10f6e1c>] ? sys_open+0x2c/0x40
[   22.637892]  [<c12e70d8>] ? sysenter_do_call+0x12/0x28
[   22.637963] ---[ end trace 9071b164502805fa ]---
[   22.645185] sd 2:0:2:0: [sdc] Attached SCSI disk
[   22.659254] sd 2:0:4:0: [sde] Attached SCSI disk
[   34.493348] mptbase: ioc1: ERROR - Wait IOC_READY state (0x20000000) timeout(15)!
[   38.883345] ioc1: LSI53C1030 B2: Capabilities={Initiator}
[   39.283343] ioc0: LSI53C1030 B2: Capabilities={Initiator}
[   40.567328] scsi3 : ioc1: LSI53C1030 B2, FwRev=01000e00h, Ports=1, MaxQ=222, IRQ=28
...

This is 3.0.23.  Line 1474 of block/genhd.c is like this:

static void __disk_unblock_events(struct gendisk *disk, bool check_now)
{
        struct disk_events *ev = disk->ev;
...
        if (WARN_ON_ONCE(ev->block <= 0))  <==== this one
                goto out_unlock;
...

The machine has the following SCSI controller:

08:07.1 SCSI storage controller: LSI Logic / Symbios Logic 53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 07)
	Subsystem: IBM Device 026c
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz+ UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 72 (4250ns min, 4500ns max), Cache Line Size: 32 bytes
	Interrupt: pin B routed to IRQ 28
	Region 0: I/O ports at 2700 [size=256]
	Region 1: Memory at f9fd0000 (64-bit, non-prefetchable) [size=64K]
	Region 3: Memory at f9fc0000 (64-bit, non-prefetchable) [size=64K]
	[virtual] Expansion ROM at a0200000 [disabled] [size=1M]
	Capabilities: [50] Power Management version 2
		Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [58] MSI: Enable- Count=1/1 Maskable- 64bit+
		Address: 0000000000000000  Data: 0000
	Capabilities: [68] PCI-X non-bridge device
		Command: DPERE- ERO- RBC=512 OST=1
		Status: Dev=08:07.1 64bit+ 133MHz+ SCD- USC- DC=simple DMMRBC=2048 DMOST=8 DMCRS=16 RSCEM- 266MHz- 533MHz-
	Kernel driver in use: mptspi

with 5 parallel scsi drives attached to it.  In the kernel
config, SCSI bus asyncronous scanning (CONFIG_SCSI_SCAN_ASYNC)
is enabled.

The system appears to work fine so far, but these messages,
together with a few errors and delays around, are a bit
worrying.  What the problem is, any suggestion?

Complete bootup dmesg is attached.

Thank you!

/mjt