The block that tests the call to umask via syscall
was commented out in this case and the module was
recompiled.

==================================================
page_fault: wrong gs 0 expected ffffffff805fb540
Unable to handle kernel NULL pointer dereference at virtual address 000000000000
0008
 printing rip:
ffffffff80110053
PML4 17bb83067 PGD 17bb7d067 PMD 0 
Oops: 0002
CPU 1 
Pid: 2218, comm: insmod Not tainted
RIP: 0010:[<ffffffff80110053>]{system_call+3}
RSP: 0018:000001017bb85e30  EFLAGS: 00010012
RAX: 000000000000005f RBX: ffffffff8040ed20 RCX: ffffffffa00810cb
RDX: 0000000001000000 RSI: 0000000000000000 RDI: 00000000000001b6
RBP: ffffffffa0081000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000212 R12: 0000000000553f30
R13: 00000000000000b8 R14: 000000000000000c R15: 000001017e95b3c0
FS:  0000002a9557d4c0(0000) GS:ffffffff805fb540(0000) knlGS:ffffffff805fb540
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000008 CR3: 0000000018216000 CR4: 00000000000006e0

Call Trace: [<ffffffffa008113c>]{:syscall_test:syscall_test_init+28} 
       [<ffffffff801256b6>]{sys_init_module+1686} [<ffffffffa00810b8>] 
       [<ffffffff801100c7>]{system_call+119} 
Process insmod (pid: 2218, stackpage=1017bb85000)
Stack: 000001017bb85e30 0000000000000018 ffffffffa008113c 0000000000553f30 
       ffffffff801256b6 000001017bb30000 000001017e99b440 000001017e99b400 
       0000000000554126 000001017bb30000 000001017bb32000 ffffff00000e5000 
       0000000000000246 00000000000000b8 ffffffffa007c000 ffffffffa00810b8 
       0000000000000608 0000000000000000 0000000000000000 0000000000000000 
       0000000000000000 0000000000000000 0000000000000000 0000000000000000 
       0000000000000000 0000000000000000 0000000000000000 0000000000000000 
       0000000000000000 0000000000000000 0000000000000000 0000000000000000 
       0000000000000000 0000000000000000 0000000000000000 0000000000000000 
       0000002a958aa6c0 0000000000000000 00000000005538d0 00000000005514e0 
Call Trace: [<ffffffffa008113c>]{:syscall_test:syscall_test_init+28} 
       [<ffffffff801256b6>]{sys_init_module+1686} [<ffffffffa00810b8>] 
       [<ffffffff801100c7>]{system_call+119} 

Code: 65 48 89 24 25 08 00 00 00 65 48 8b 24 25 00 00 00 00 fb 48

Kernel panic: Fatal exception

=========================================

syscall_test_init() dump:

0x0000000000000060 <syscall_test_init+0>:       sub    $0x8,%rsp
0x0000000000000064 <syscall_test_init+4>:       mov    $0x0,%rdi
0x000000000000006b <syscall_test_init+11>:      xor    %eax,%eax
0x000000000000006d <syscall_test_init+13>:      callq  0x72 <syscall_test_init+18>
0x0000000000000072 <syscall_test_init+18>:      mov    $0x1b6,%edi
0x0000000000000077 <syscall_test_init+23>:      callq  0x0 <wrapper_umask>
0x000000000000007c <syscall_test_init+28>:      mov    $0x0,%rdi
0x0000000000000083 <syscall_test_init+35>:      mov    %rax,%rsi
0x0000000000000086 <syscall_test_init+38>:      xor    %eax,%eax
0x0000000000000088 <syscall_test_init+40>:      callq  0x8d <syscall_test_init+45>
0x000000000000008d <syscall_test_init+45>:      xor    %eax,%eax
0x000000000000008f <syscall_test_init+47>:      add    $0x8,%rsp
0x0000000000000093 <syscall_test_init+51>:      retq
0x0000000000000094 <syscall_test_init+52>:      data16
0x0000000000000095 <syscall_test_init+53>:      data16
0x0000000000000096 <syscall_test_init+54>:      data16
0x0000000000000097 <syscall_test_init+55>:      nop
0x0000000000000098 <syscall_test_init+56>:      data16
0x0000000000000099 <syscall_test_init+57>:      data16
0x000000000000009a <syscall_test_init+58>:      data16
0x000000000000009b <syscall_test_init+59>:      nop
0x000000000000009c <syscall_test_init+60>:      data16
0x000000000000009d <syscall_test_init+61>:      data16
0x000000000000009e <syscall_test_init+62>:      data16
0x000000000000009f <syscall_test_init+63>:      nop