System was panicked inside task_tgid_nr_ns because of null pointer dereference

Issue

• System panic in ps while reading /proc

RHEL 6
crash> bt
PID: 19823  TASK: ffff882ff03f3520  CPU: 15  COMMAND: "ps"
 #0 [ffff882a937b1890] machine_kexec at ffffffff8103b60b
 #1 [ffff882a937b18f0] crash_kexec at ffffffff810c99a2
 #2 [ffff882a937b19c0] oops_end at ffffffff8152e8e0
 #3 [ffff882a937b19f0] no_context at ffffffff8104c80b
 #4 [ffff882a937b1a40] __bad_area_nosemaphore at ffffffff8104ca95
 #5 [ffff882a937b1a90] bad_area at ffffffff8104cbbe
 #6 [ffff882a937b1ac0] __do_page_fault at ffffffff8104d3c3
 #7 [ffff882a937b1be0] do_page_fault at ffffffff8153082e
 #8 [ffff882a937b1c10] page_fault at ffffffff8152dbd5
    [exception RIP: task_tgid_nr_ns+9]
    RIP: ffffffff810999f9  RSP: ffff882a937b1cc8  RFLAGS: 00010286
    RAX: 0000000000000000  RBX: ffff882fefc0d9c0  RCX: 0000000000000001
    RDX: 0000000000000000  RSI: ffffffff81aa63e0  RDI: 000000000000000d
    RBP: ffff882a937b1cc8   R8: 0000000000000ff4   R9: 0000000000000000
    R10: 0000000000000001  R11: 0000000000000246  R12: ffff882fe7c0d520
    R13: ffff882a937b1dce  R14: ffffffff81aa63e0  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #9 [ffff882a937b1cd0] proc_pid_status at ffffffff81201a40
#10 [ffff882a937b1e20] proc_single_show at ffffffff811fd274
#11 [ffff882a937b1e70] seq_read at ffffffff811b4252
#12 [ffff882a937b1ef0] vfs_read at ffffffff8118ecd5
#13 [ffff882a937b1f30] sys_read at ffffffff8118ee11
#14 [ffff882a937b1f80] system_call_fastpath at ffffffff8100b0d2
    RIP: 0000003dd66db4c0  RSP: 00007ffd6a7cfb50  RFLAGS: 00000246
    RAX: 0000000000000000  RBX: ffffffff8100b0d2  RCX: 0000000000000000
    RDX: 00000000000003ff  RSI: 0000003dd6c118c0  RDI: 0000000000000005  <--- file number
    RBP: 0000000000000005   R8: 0000000000000000   R9: 0000003dd6a0be08
    R10: 0000000000000000  R11: 0000000000000246  R12: 0000000000000020
    R13: 0000000000815410  R14: 0000003dd6c118c0  R15: 0000000000815410
    ORIG_RAX: 0000000000000000  CS: 0033  SS: 002b

crash> files
PID: 19823  TASK: ffff882ff03f3520  CPU: 15  COMMAND: "ps"
ROOT: /    CWD: /
 FD       FILE            DENTRY           INODE       TYPE PATH
  0 ffff882a84b35300 ffff882a0b1c16c0 ffff88302bfe5c58 FIFO 
  1 ffff882a56535680 ffff882ff385ee40 ffff882a6dc870c8 FIFO 
  2 ffff882ff13cd8c0 ffff883027498240 ffff883047019048 FIFO 
  3 ffff8830351e2480 ffff882e8d7cfe40 ffff882a0b244598 REG  /proc/meminfo
  4 ffff882a35d7b900 ffff88185b800a40 ffff88305b802078 DIR  /proc/
  5 ffff882a901a09c0 ffff882e86489080 ffff882ce3c62078 REG  /proc/22321/status   <--- file

RHEL 7
crash> bt
    PID: 13183    TASK: ffff959aa097a100  CPU: 3    COMMAND: "ps"
     #0 [ffff959aedcab950] machine_kexec at ffffffffa0669514
     #1 [ffff959aedcab9b0] __crash_kexec at ffffffffa0729e82
     #2 [ffff959aedcaba80] crash_kexec at ffffffffa0729f78
     #3 [ffff959aedcaba98] oops_end at ffffffffa0dbc818
     #4 [ffff959aedcabac0] no_context at ffffffffa067974c
     #5 [ffff959aedcabb10] __bad_area_nosemaphore at ffffffffa0679a2a
     #6 [ffff959aedcabb60] bad_area_nosemaphore at ffffffffa0679b54
     #7 [ffff959aedcabb70] __do_page_fault at ffffffffa0dbf8d0
     #8 [ffff959aedcabbe0] do_page_fault at ffffffffa0dbfb05
     #9 [ffff959aedcabc10] page_fault at ffffffffa0dbb7b8
        [exception RIP: task_tgid_nr_ns+0x10] <-------
        RIP: ffffffffa06c72e0  RSP: ffff959aedcabcc0  RFLAGS: 00010282
        RAX: ffffffffffffffff  RBX: ffff958bb79dbe40  RCX: 0000000000000010
        RDX: ffff959a50d12000  RSI: ffffffffa1255280  RDI: ffff958c594e0000
        RBP: ffff959aedcabcc0   R8: 00000000093a656d   R9: ffff958c7fc03300
        R10: ffff958c7fc03300  R11: ffffffffa07e9f65  R12: ffff959ae2393180
        R13: ffff958bb79dbe40  R14: ffff959ad01a5080  R15: ffff959ad01a5080
        ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
    #10 [ffff959aedcabcc8] proc_pid_status at ffffffffa08df934
    #11 [ffff959aedcabde0] proc_single_show at ffffffffa08da132
    #12 [ffff959aedcabe18] seq_read at ffffffffa08857e8
    #13 [ffff959aedcabe88] vfs_read at ffffffffa085bb2f
    #14 [ffff959aedcabeb8] sys_read at ffffffffa085c9a5
    #15 [ffff959aedcabf00] unload_network_ops_symbols at ffffffffc04cb587 [falcon_lsm_pinned_14812]
    #16 [ffff959aedcabf50] tracesys at ffffffffa0dc562e (via system_call)
        RIP: 00007ff2be456b40  RSP: 00007ffe889b8438  RFLAGS: 00000246
        RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: ffffffffffffffff
        RDX: 0000000000000800  RSI: 0000000000b35350  RDI: 0000000000000006 
        RBP: 00007ff2bed7dab0   R8: 0000000000000000   R9: 00007ff2be3b42cd
        R10: 0000000000000000  R11: 0000000000000246  R12: 0000000000000006
        R13: 0000000000000000  R14: 0000000000000004  R15: 0000000000000000
        ORIG_RAX: 0000000000000000  CS: 0033  SS: 002b