Kernel panic at xfs_ordered_write_end_hook() function of unsigned kernel module dtfilter

Issue

• The system crashed with the following call traces in the kernel ring buffer :

[7997680.311798] BUG: unable to handle kernel NULL pointer dereference at 0000000000000088
[7997680.312855] IP: [<ffffffffa04be47a>] xfs_ordered_write_end_hook+0xda/0x210 [dtfilter]
[7997680.313475] PGD 8000000166b1d067 PUD 14f67c067 PMD 0 
[7997680.313983] Oops: 0000 [#1] SMP 
[..]
[7997680.335466] Call Trace:
[7997680.336687]  [<ffffffffa026dba0>] ? xfs_vm_bmap+0xa0/0xa0 [xfs]
[7997680.337910]  [<ffffffff81187288>] generic_file_buffered_write+0x198/0x2c0
[7997680.339147]  [<ffffffffa027b91b>] xfs_file_buffered_aio_write+0x10b/0x260 [xfs]
[7997680.341484]  [<ffffffff81216492>] ? user_path_at_empty+0x72/0xc0
[7997680.343485]  [<ffffffffa027bbfd>] xfs_file_aio_write+0x18d/0x1a0 [xfs]
[7997680.346274]  [<ffffffff81203cb3>] do_sync_write+0x93/0xe0
[7997680.347803]  [<ffffffff81204530>] vfs_write+0xc0/0x1f0
[7997680.350409]  [<ffffffff8120505f>] SyS_write+0x7f/0xe0
[7997680.352561]  [<ffffffff816a5215>] system_call_fastpath+0x1c/0x21
[7997680.355089] Code: 83 7d b0 00 0f 84 03 01 00 00 48 8b 43 10 44 8b 6d c0 48 c1 e0 0c 41 29 c5 8b 45 bc 45 8d 74 05 00 48 8b 05 f1 b1 00 00 48 89 c7 <ff> 90 88 00 00 00 48 8b 15 e1 b1 00 00 48 8b 4a 38 4c 8b 79 58 
[7997680.358857] RIP  [<ffffffffa04be47a>] xfs_ordered_write_end_hook+0xda/0x210 [dtfilter]
[7997680.360732]  RSP <ffff88010ff8bbb0>
[7997680.362991] CR2: 0000000000000088