[RHEL 8][GPFS]crash in filp_close() when dereferencing a null filp- >f_op pointer

Issue

System crashes with console messages:

[120692.713335] Faulting instruction address: 0xc0000000005895a8
[120692.713340] Oops: Kernel access of bad area, sig: 7 [#1]
[120692.713345] LE SMP NR_CPUS=2048 NUMA PowerNV
[120692.713353] Modules linked in: nf_tables libcrc32c nfnetlink mmfs26(OE) mmfslinux(OE) tracedev(OE) mptcp_diag xsk_diag tcp_diag udp_diag raw_diag inet_diag unix_diag af_packet_diag netlink_diag 8021q garp stp mrp llc bonding uio_pci_generic vfio_pci vfio_virqfd vfio_iommu_spapr_tce vfio vfio_spapr_eeh cuse fuse rdma_ucm(OE) rdma_cm(OE) iw_cm(OE) i2c_dev ib_ipoib(OE) ib_cm(OE) ib_umad(OE) ses enclosure scsi_transport_sas xts ipmi_powernv vmx_crypto ipmi_devintf ipmi_msghandler uio_pdrv_genirq uio leds_powernv powernv_op_panel ibmpowernv auth_rpcgss sunrpc knem(OE) binfmt_misc ext4 mbcache jbd2 mlx5_ib(OE) ib_uverbs(OE) ib_core(OE) sd_mod mlx5_core(OE) mlxdevm(OE) ipr mlx_compat(OE) libata psample mlxfw(OE) tg3 tls dm_mirror dm_region_hash dm_log dm_mod opal_prd nvme nvme_core t10_pi sg
[120692.713450] CPU: 116 PID: 689024 Comm: smbd[<IP_address> Kdump: loaded Tainted: G           OE     -------- -  - 4.18.0-553.22.1.el8_10.ppc64le #1
[120692.713457] NIP:  c0000000005895a8 LR: c0000000005d064c CTR: 0000000000000000
[120692.713462] REGS: c00000131b5e3980 TRAP: 0300   Tainted: G           OE     -------- -  -  (4.18.0-553.22.1.el8_10.ppc64le)
[120692.713469] MSR:  9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE>  CR: 24242204  XER: 20040000
[120692.713481] CFAR: c0000000005d0648 DAR: 0000000000000078 DSISR: 00080000 IRQMASK: 0 
                GPR00: c0000000005d064c c00000131b5e3c10 c00000000220f300 c000000f92aab500 
                GPR04: c000000180936f00 0000000000000001 c00000131b5e3be8 0000000000042088 
                GPR08: 0000000000002000 0000000000000000 0000000000000120 0000201ffac50000 
                GPR12: 0000000024242202 c000201fffe26800 0000000055823118 0000000000000000 
                GPR16: 0000000000000000 0000000000000000 0000000000000010 00000000bb9fede5 
                GPR20: 0000000000000002 00007fffb7665070 0000000000000003 0000000000000001 
                GPR24: 00007fffb76608a8 0000000000000000 c000000180936f00 0000000000000005 
                GPR28: 0000000000000025 0000000000000000 c000000180936f00 c000000f92aab500 
[120692.713534] NIP [c0000000005895a8] filp_close+0x48/0xe0
[120692.713544] LR [c0000000005d064c] put_files_struct.part.4+0xdc/0x190
[120692.713551] Call Trace:
[120692.713553] [c00000131b5e3c10] [c00000131b5e3c60] 0xc00000131b5e3c60 (unreliable)
[120692.713559] [c00000131b5e3c90] [c0000000005d064c] put_files_struct.part.4+0xdc/0x190
[120692.713565] [c00000131b5e3cf0] [c00000000017a8a8] do_exit+0x498/0xd60
[120692.713571] [c00000131b5e3dc0] [c00000000017b240] do_group_exit+0x60/0x110
[120692.713577] [c00000131b5e3e00] [c00000000017b314] sys_exit_group+0x24/0x30
[120692.713582] [c00000131b5e3e20] [c00000000000b408] system_call+0x5c/0x70
[120692.713589] Instruction dump:
[120692.713593] f8010010 f821ff81 e9230038 2fa90000 419e0098 fbc10070 fbe10078 f8410018 
[120692.713603] 7c7f1b78 7c9e2378 3ba00000 e9230028 <e9290078> 2fa90000 419e0018 7d2c4b78 
[120692.713616] ---[ end trace e349243b1cfd4f50 ]---

The kernel panic stack trace is:

crash> bt
PID: 689024   TASK: c000001315b89000  CPU: 116  COMMAND: "smbd[<IP_address>"
 R0:  c0000000000e3a08    R1:  c00000010e8fbc60    R2:  c00000000220f300   
 R3:  c00000010e8fbae8    R4:  c0000000000dbe40    R5:  0000000000000000   
 R6:  0000000000000001    R7:  0000000000000003    R8:  0000000000000002   
 R9:  0000000000000000    R10: 00000000000000ff    R11: c000201ffff9c000   
 R12: 0000000031d48000    R13: c000001fff7d7880    R14: c00000010e8fbf90   
 R15: 0000000000000000    R16: 0000000000000000    R17: 0000000000000000   
 R18: 0000000000000000    R19: 0000000000000000    R20: 0000000000000000   
 R21: 0000000000000000    R22: 0000000000000000    R23: 0000000000000001   
 R24: 0000000028000000    R25: 0000000000100000    R26: 00000000000c0000   
 R27: 0000000000200000    R28: 00000000003c0000    R29: 00000000000000e8   
 R30: 000000000000001d    R31: 9000000000121033   
 NIP: c0000000000e3a08    MSR: 9000000000001033    OR3: 0000000000100000
 CTR: c000000000008000    LR:  c0000000000e3a08    XER: 0000000020040000
 CCR: 0000000048004422    MQ:  000000000000001d    DAR: c00000010e8fbc60
 DSISR: 0000000000000000     Syscall Result: c0000000000dcaac
 [NIP  : pnv_smp_cpu_kill_self+0x308]
 [LR   : pnv_smp_cpu_kill_self+0x308]
 #0 [c00000131b5e37e0] crash_kexec at c0000000002a2680
 #1 [c00000131b5e3820] oops_end at c000000000021ad8
 #2 [c00000131b5e38a0] bad_page_fault at c00000000008663c
 #3 [c00000131b5e3910] handle_page_fault at c00000000000a760
 Data Access [300] exception frame:
 R0:  c0000000005d064c    R1:  c00000131b5e3c10    R2:  c00000000220f300   
 R3:  c000000f92aab500    R4:  c000000180936f00    R5:  0000000000000001   
 R6:  c00000131b5e3be8    R7:  0000000000042088    R8:  0000000000002000   
 R9:  0000000000000000    R10: 0000000000000120    R11: 0000201ffac50000   
 R12: 0000000024242202    R13: c000201fffe26800    R14: 0000000055823118   
 R15: 0000000000000000    R16: 0000000000000000    R17: 0000000000000000   
 R18: 0000000000000010    R19: 00000000bb9fede5    R20: 0000000000000002   
 R21: 00007fffb7665070    R22: 0000000000000003    R23: 0000000000000001   
 R24: 00007fffb76608a8    R25: 0000000000000000    R26: c000000180936f00   
 R27: 0000000000000005    R28: 0000000000000025    R29: 0000000000000000   
 R30: c000000180936f00    R31: c000000f92aab500   
 NIP: c0000000005895a8    MSR: 9000000000009033    OR3: c0000000005d0648
 CTR: 0000000000000000    LR:  c0000000005d064c    XER: 0000000020040000
 CCR: 0000000024242204    MQ:  0000000000000000    DAR: 0000000000000078
 DSISR: 0000000000080000     Syscall Result: 0000000000000000
 [NIP  : filp_close+0x48]
 [LR   : put_files_struct+0xdc]
 #4 [c00000131b5e3c10] filp_close at c0000000005895a8
 #5 [c00000131b5e3c90] put_files_struct at c0000000005d064c  (unreliable)
 #6 [c00000131b5e3cf0] do_exit at c00000000017a8a8
 #7 [c00000131b5e3dc0] do_group_exit at c00000000017b240
 #8 [c00000131b5e3e00] sys_exit_group at c00000000017b314
 #9 [c00000131b5e3e20] system_call at c00000000000b408
 System Call [c00] exception frame:
 R0:  00000000000000ea    R1:  00007fffd0407830    R2:  00007fffb7667300   
 R3:  0000000000000000    R4:  0000000000000000    R5:  0000000000000000   
 R6:  0000000000000001    R7:  0000000000000000    R8:  0000000000000000   
 R9:  0000000000000000    R10: 0000000000000000    R11: 0000000000000000   
 R12: 0000000000000000    R13: 00007fffb42f0c90    R14: 0000000055823118   
 R15: 0000000000000000    R16: 0000000000000000    R17: 0000000000000000   
 R18: 0000000000000010    R19: 00000000bb9fede5    R20: 0000000000000002   
 R21: 00007fffb7665070    R22: 0000000000000003    R23: 0000000000000001   
 R24: 00007fffb76608a8    R25: 0000000000000000    R26: 0000000000000000   
 R27: 0000000000000001    R28: 0000000000000000    R29: 0000000000000000   
 R30: 00007fffb42e9cd8    R31: 0000000000000000   
 NIP: 00007fffb755387c    MSR: 900000000280f033    OR3: 0000000000000000
 CTR: 0000000000000000    LR:  00007fffb74acff4    XER: 0000000000000000
 CCR: 0000000044242402    MQ:  0000000000000000    DAR: 00007fff9e1b0118
 DSISR: 0000000002040000     Syscall Result: 0000000000000000