Boot failure (crash at boot) with Supermicro H8QG6

Issue

• Since updating to kernel 2.6.32-504.el6.x86_64, on a machine with Supermicro H8QG6 motherboard, the system is unable to boot. When enabling serial console output, the following kernel oops is captured:

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8128c3fd>] find_next_bit+0x7d/0xb0
PGD 0 
Oops: 0000 [#1] SMP 
last sysfs file: 
CPU 1 
Modules linked in:

Pid: 1, comm: swapper Tainted: G        W  ---------------    2.6.32-504.el6.x86_64 #1 Supermicro H8QG6/H8QG6
RIP: 0010:[<ffffffff8128c3fd>]  [<ffffffff8128c3fd>] find_next_bit+0x7d/0xb0
RSP: 0018:ffff8810119bdc90  EFLAGS: 00010202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000020 RDI: 0000000000000020
RBP: ffff8810119bdc90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff81c09ec0
R13: ffffffff81b049a0 R14: 0000000000000004 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff880061a20000(0000) knlGS:0000000000000000
CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000001a85000 CR4: 00000000000407e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process swapper (pid: 1, threadinfo ffff8810119bc000, task ffff8810119bb500)
Stack:
 ffff8810119bdcb0 ffffffff8128c079 ffff8810109d8090 ffff8810109d8000
<d> ffff8810119bdd10 ffffffff812b0041 0000000000000000 0000000000000000
<d> ffffffff81b049a0 ffff8810109d8000 ffffffff81871c40 ffffffff8136c422
Call Trace:
 [<ffffffff8128c079>] cpumask_next_and+0x29/0x50
 [<ffffffff812b0041>] pci_device_probe+0xb1/0x120
 [<ffffffff8136c422>] ? driver_sysfs_add+0x62/0x90
 [<ffffffff8136c6bc>] driver_probe_device+0x9c/0x3e0
 [<ffffffff8136caab>] __driver_attach+0xab/0xb0
 [<ffffffff8136ca00>] ? __driver_attach+0x0/0xb0
 [<ffffffff8136b8a4>] bus_for_each_dev+0x64/0x90
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff8136c35e>] driver_attach+0x1e/0x20
 [<ffffffff81c63df8>] agp_amd64_init+0xa8/0xc8
 [<ffffffff81c437c2>] gart_iommu_init+0x2f/0x4f1
 [<ffffffff811349f9>] ? free_pages+0x49/0x50
 [<ffffffff8104b172>] ? free_init_pages+0xf2/0x110
 [<ffffffff81c2d92b>] ? populate_rootfs+0x0/0xd3
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c33814>] pci_iommu_init+0x18/0x21
 [<ffffffff8100204c>] do_one_initcall+0x3c/0x1d0
 [<ffffffff81c2a8e4>] kernel_init+0x29b/0x2f7
 [<ffffffff8100c20a>] child_rip+0xa/0x20
 [<ffffffff81c2a649>] ? kernel_init+0x0/0x2f7
 [<ffffffff8100c200>] ? child_rip+0x0/0x20
Code: 40 eb 17 0f 1f 00 49 8b 00 48 85 c0 75 36 49 83 c0 08 49 83 c1 40 48 83 ef 40 48 f7 c7 c0 ff ff ff 75 e3 48 85 ff 4c 89 c8 74 20 <49> 8b 00 b9 40 00 00 00 48 c7 c2 ff ff ff ff 29 f9 48 d3 ea 48 
RIP  [<ffffffff8128c3fd>] find_next_bit+0x7d/0xb0
 RSP <ffff8810119bdc90>
CR2: 0000000000000000
---[ end trace a7919e7f17c0a727 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1, comm: swapper Tainted: G      D W  ---------------    2.6.32-504.el6.x86_64 #1
Call Trace:
 [<ffffffff815292bc>] ? panic+0xa7/0x16f
 [<ffffffff8152e094>] ? oops_end+0xe4/0x100
 [<ffffffff8104c80b>] ? no_context+0xfb/0x260
 [<ffffffff8104ca95>] ? __bad_area_nosemaphore+0x125/0x1e0
 [<ffffffff8106d175>] ? enqueue_entity+0x125/0x450
 [<ffffffff8104cb63>] ? bad_area_nosemaphore+0x13/0x20
 [<ffffffff8104d2bf>] ? __do_page_fault+0x31f/0x480
 [<ffffffff8152a8c5>] ? schedule_timeout+0x215/0x2e0
 [<ffffffff8128cbb0>] ? idr_get_empty_slot+0x110/0x2c0
 [<ffffffff8152ffbe>] ? do_page_fault+0x3e/0xa0
 [<ffffffff8152d375>] ? page_fault+0x25/0x30
 [<ffffffff8128c3fd>] ? find_next_bit+0x7d/0xb0
 [<ffffffff8128c079>] ? cpumask_next_and+0x29/0x50
 [<ffffffff812b0041>] ? pci_device_probe+0xb1/0x120
 [<ffffffff8136c422>] ? driver_sysfs_add+0x62/0x90
 [<ffffffff8136c6bc>] ? driver_probe_device+0x9c/0x3e0
 [<ffffffff8136caab>] ? __driver_attach+0xab/0xb0
 [<ffffffff8136ca00>] ? __driver_attach+0x0/0xb0
 [<ffffffff8136b8a4>] ? bus_for_each_dev+0x64/0x90
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff8136c35e>] ? driver_attach+0x1e/0x20
 [<ffffffff81c63df8>] ? agp_amd64_init+0xa8/0xc8
 [<ffffffff81c437c2>] ? gart_iommu_init+0x2f/0x4f1
 [<ffffffff811349f9>] ? free_pages+0x49/0x50
 [<ffffffff8104b172>] ? free_init_pages+0xf2/0x110
 [<ffffffff81c2d92b>] ? populate_rootfs+0x0/0xd3
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c337fc>] ? pci_iommu_init+0x0/0x21
 [<ffffffff81c33814>] ? pci_iommu_init+0x18/0x21
 [<ffffffff8100204c>] ? do_one_initcall+0x3c/0x1d0
 [<ffffffff81c2a8e4>] ? kernel_init+0x29b/0x2f7
 [<ffffffff8100c20a>] ? child_rip+0xa/0x20
 [<ffffffff81c2a649>] ? kernel_init+0x0/0x2f7
 [<ffffffff8100c200>] ? child_rip+0x0/0x20