RHEL6: Kernel panic in unlink_anon_vmas() while freeing anonymous pages.

Issue

• System crashed with following panic message in unlink_anon_vmas() routine

  kernel BUG at mm/rmap.c:381!
  invalid opcode: 0000 [#1] SMP 
  ...
  RIP: 0010:[<ffffffff8115c3c7>]  [<ffffffff8115c3c7>] unlink_anon_vmas+0x167/0x1b0
  ...
  Process <process> (pid: 13043, threadinfo ffff88075c8b4000, task ffff8807da177520)
  ...
  Call Trace:
   [<ffffffff8114ecf4>] free_pgtables+0x44/0x120
   [<ffffffff811563f0>] exit_mmap+0xb0/0x180
   [<ffffffff8107474c>] mmput+0x6c/0x120
   [<ffffffff8107c22b>] exit_mm+0x12b/0x180
   [<ffffffff8107c5df>] do_exit+0x15f/0x870
   [<ffffffff81090eec>] ? send_sig+0x1c/0x20
   [<ffffffff8119d065>] ? pipe_write+0x5b5/0x6b0
   [<ffffffff8107cd48>] do_group_exit+0x58/0xd0
   [<ffffffff810929f6>] get_signal_to_deliver+0x1f6/0x460
   [<ffffffff8100a285>] do_signal+0x75/0x870
   [<ffffffff8123ee7f>] ? selinux_file_permission+0xbf/0x150
   [<ffffffff81231c26>] ? security_file_permission+0x16/0x20
   [<ffffffff81191e08>] ? vfs_write+0xb8/0x1a0
   [<ffffffff8100ab10>] do_notify_resume+0x90/0xc0
   [<ffffffff8100b3a1>] int_signal+0x12/0x17