System crashed with error swiotlb_unmap_sg+0x2e/0x126

Issue

• After the issues in connectivity to SAN, system got rebooted with following errors on console:

  qla2xxx 0000:0d:00.0: scsi(3:10:6): Abort command issued -- 1 1519053ca 2002.
  qla2xxx 0000:0d:00.0: scsi(3:10:6): Abort command issued -- 1 1519053ca 2002.
  qla2xxx 0000:0d:00.0: scsi(3:10:2): Abort command issued -- 1 1519053d6 2002.
  Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP: 
   [<ffffffff8014f924>] swiotlb_unmap_sg+0x2e/0x126
  PGD 3790b067 PUD 5b0a6067 PMD 0 
  Oops: 0000 [1] SMP 
  last sysfs file: /class/fc_remote_ports/rport-2:0-67/roles
  [...]
  Pid: 2406, comm: egrep Tainted: G      2.6.18-128.el5 #1
  RIP: 0010:[<ffffffff8014f924>]  [<ffffffff8014f924>] swiotlb_unmap_sg+0x2e/0x126
  RSP: 0000:ffff81022ff37e48  EFLAGS: 00010297
  RAX: ffffffff802f68e0 RBX: 0000000000000000 RCX: 0000000000000002
  RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff81022faf7870
  RBP: 0000000000000002 R08: 0000000000000006 R09: 000000000000003a
  R10: ffff81022ff37ca8 R11: 0000000000000004 R12: 0000000000000000
  R13: 0000000000000001 R14: ffff81022faf7870 R15: ffff810021a87f58
  FS:  00002ac8cf0d77e0(0000) GS:ffff81022ff12840(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000000000000 CR3: 00000000cf365000 CR4: 00000000000006e0
  Process egrep (pid: 2406, threadinfo ffff810021a86000, task ffff8100535520c0)
  Stack:  ffff81022de52380 ffff81022dc14c40 ffff81022de5c4f8 ffff81022de52380
   ffffc2000002c000 ffffffff8812769a ffff81001102df80 ffff81022dc14c40
   ffff81022de5c4f8 ffffffff881276f6 ffffc2000002c000 0000000000000031
  Call Trace:
   <IRQ>  [<ffffffff8812769a>] :qla2xxx:qla2x00_sp_free_dma+0x4c/0x94
   [<ffffffff881276f6>] :qla2xxx:qla2x00_sp_compl+0x14/0x33
   [<ffffffff8813518b>] :qla2xxx:qla24xx_process_response_queue+0xa8/0x224
   [<ffffffff881366ac>] :qla2xxx:qla24xx_intr_handler+0x13b/0x1be
   [<ffffffff8004f027>] hrtimer_run_queues+0xfa/0x197
   [<ffffffff80010a46>] handle_IRQ_event+0x51/0xa6
   [<ffffffff800b7ade>] __do_IRQ+0xa4/0x103
   [<ffffffff80011fbc>] __do_softirq+0x89/0x133
   [<ffffffff8006c95d>] do_IRQ+0xe7/0xf5
   [<ffffffff8005d615>] ret_from_intr+0x0/0xa
   <EOI> 
  
  Code: 48 8b 0b 48 8b 73 10 48 8b 39 48 c1 ef 33 48 89 f8 48 c1 e8 
  RIP  [<ffffffff8014f924>] swiotlb_unmap_sg+0x2e/0x126
   RSP <ffff81022ff37e48>