NULL pointer dereference in __vm_enough_memory

Issue

• NULL pointer dereference occurred inside the __vm_enough_memory() function:

 #0 [ffff811554685420] crash_kexec at ffffffff800b099c
 #1 [ffff8115546854e0] __die at ffffffff80065137
 #2 [ffff811554685520] do_page_fault at ffffffff80067484
 #3 [ffff811554685610] error_exit at ffffffff8005dde9
    [exception RIP: __vm_enough_memory+0xd2]
    RIP: ffffffff80035b6b  RSP: ffff8115546856c0  RFLAGS: 00010202
    RAX: 0000000000a235ee  RBX: 000000003f5d10f8  RCX: 0000000000a235ee
    RDX: 0000000000000000  RSI: 0000000000000064  RDI: fffffffffffffe56
    RBP: 0000000000000001   R8: ffff811554685660   R9: 0000000000000000
    R10: ffff81107837d8a0  R11: 0000000000000048  R12: 0000000000000001
    R13: 0000000000000000  R14: 00000000000000f6  R15: 0000000000000000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0000
 #4 [ffff8115546856e8] shmem_getpage at ffffffff800dd122
 #5 [ffff811554685808] shmem_nopage at ffffffff800dd9cb
 #6 [ffff811554685828] __handle_mm_fault at ffffffff80008972
 #7 [ffff8115546858e8] get_user_pages at ffffffff800d126f
 #8 [ffff811554685938] vx_dio_physio at ffffffff8868452a [vxfs]
 #9 [ffff811554685a58] vx_dio_rdwri at ffffffff885ad699 [vxfs]
#10 [ffff811554685c68] vx_dio_read at ffffffff8866dffb [vxfs]
#11 [ffff811554685d18] vx_read1 at ffffffff8866e598 [vxfs]
#12 [ffff811554685da8] vx_vop_read at ffffffff8865695b [vxfs]
#13 [ffff811554685e18] vx_naio_do_work at ffffffff886415f9 [vxfs]
#14 [ffff811554685ee8] vx_naio_worker at ffffffff8864199a [vxfs]
#15 [ffff811554685f08] vx_kthread_init at ffffffff88651474 [vxfs]
#16 [ffff811554685f48] kernel_thread at ffffffff8005dfb1