Generating a sos report on a system with Dell PERC H755/H750 adapter led to a system crash

Issue

• The system crashed while generating a sosreport on a system with DELL PERC H750/H755 adapter and third-party MegaCli rpm package installed.

• The system crashed via hung_task panic with the following call traces from the stalled task in megasas_issue_blocked_cmd().

kernel: INFO: task MegaCli64:14038 blocked for more than 120 seconds.
kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kernel: MegaCli64 D ffff92f757b568e0 0 14038 14033 0x00000000
kernel: Call Trace:
kernel: [<ffffffff8898c3f9>] schedule+0x29/0x70
kernel: [<ffffffffc0470f25>] megasas_issue_blocked_cmd+0x125/0x220 [megaraid_sas]
kernel: [<ffffffff882c7080>] ? wake_up_atomic_t+0x30/0x30
kernel: [<ffffffffc047864a>] megasas_mgmt_fw_ioctl+0x64a/0xd00 [megaraid_sas]
kernel: [<ffffffffc0478e9a>] megasas_mgmt_ioctl_fw.isra.29+0x19a/0x1e0 [megaraid_sas]
kernel: [<ffffffffc0479178>] megasas_mgmt_ioctl+0x28/0x40 [megaraid_sas]
kernel: [<ffffffff884638d0>] do_vfs_ioctl+0x3a0/0x5b0
kernel: [<ffffffff88994678>] ? __do_page_fault+0x238/0x500
kernel: [<ffffffff88463b61>] SyS_ioctl+0x81/0xa0
kernel: [<ffffffff88999f92>] system_call_fastpath+0x25/0x2a

• The sosreport command hangs with hung task warnings.

kernel: INFO: task MegaCli64:14038 blocked for more than 120 seconds.
kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kernel: MegaCli64 D ffff92f757b568e0 0 14038 14033 0x00000000
kernel: Call Trace:
kernel: [<ffffffff8898c3f9>] schedule+0x29/0x70
kernel: [<ffffffffc0470f25>] megasas_issue_blocked_cmd+0x125/0x220 [megaraid_sas]
kernel: [<ffffffff882c7080>] ? wake_up_atomic_t+0x30/0x30
kernel: [<ffffffffc047864a>] megasas_mgmt_fw_ioctl+0x64a/0xd00 [megaraid_sas]
kernel: [<ffffffffc0478e9a>] megasas_mgmt_ioctl_fw.isra.29+0x19a/0x1e0 [megaraid_sas]
kernel: [<ffffffffc0479178>] megasas_mgmt_ioctl+0x28/0x40 [megaraid_sas]
kernel: [<ffffffff884638d0>] do_vfs_ioctl+0x3a0/0x5b0
kernel: [<ffffffff88994678>] ? __do_page_fault+0x238/0x500
kernel: [<ffffffff88463b61>] SyS_ioctl+0x81/0xa0
kernel: [<ffffffff88999f92>] system_call_fastpath+0x25/0x2a