Why does 'kdump' hang when invoking a crash through an iLO session on HP Proliant servers?

Issue

• When triggering a kernel crash using SysRq to test kdump functionality kdump hangs and fails to create a valid kernel dump.

• A similar trace to the one below might or might not be displayed:

[<c2717758>] ? usb_add_hcd+0x488/0x7b0
[<c2725df7>] ? usb_hcd_pci_probe+0x1c7/0x4f0
[<c2591f9b>] ? __sysfs_add_one+0x5b/0x90
[<c2591b34>] ? sysfs_addrm_finish+0x14/0x1e0
[<c2591fec>] ? sysfs_add_one+0x1c/0xb0
[<c2619f5b>] ? local_pci_probe+0xb/0x10
[<c261ad41>] ? pci_device_probe+0x61/0x80
[<c26cb6d7>] ? driver_probe_device+0x87/0x290
[<c261a032>] ? pci_match_device+0x12/0xa0
[<c26cb959>] ? __driver_attach+0x79/0x80
[<c26cb8e0>] ? __driver_attach+0x0/0x80
[<c26cae62>] ? bus_for_each_dev+0x52/0x80
[<c26cb4c6>] ? driver_attach+0x16/0x20
[<c26cb8e0>] ? __driver_attach+0x0/0x80
[<c26ca777>] ? bus_add_driver+0x1b7/0x2b0
[<c261ac80>] ? pci_device_remove+0x0/0x40