Kernel crash :BUG_ON "kernel BUG at mm/rmap.c:1041!" in __page_set_anon_rmap() when vma->anon_vma==NULL

Issue

• kernel crashes with a message

 PANIC: "kernel BUG at mm/rmap.c:1041!"

• The panicking thread:

PID: 2070313 TASK: ffff897c11bcd080 CPU: 2  COMMAND: "ray::ImplicitFu"
 #0 [ffff958708b57918] machine_kexec at ffffffffa4a67ede
 #1 [ffff958708b57970] __crash_kexec at ffffffffa4baea5a
 #2 [ffff958708b57a30] crash_kexec at ffffffffa4baf991
 #3 [ffff958708b57a48] oops_end at ffffffffa4a274f1
 #4 [ffff958708b57a68] do_trap at ffffffffa4a239a7
 #5 [ffff958708b57ab0] do_invalid_op at ffffffffa4a244b6
 #6 [ffff958708b57ad0] invalid_op at ffffffffa5400d64
   [exception RIP: __page_set_anon_rmap+96]
   RIP: ffffffffa4ce3a10 RSP: ffff958708b57b88 RFLAGS: 00010246
   RAX: 0000000000000020 RBX: ffff890b73de0658 RCX: 0000000000000001
   RDX: 000014f54bf47000 RSI: ffff890b73de0658 RDI: ffffb6a91ffb38c0
   RBP: ffff892653daaa38  R8: 0000000000000000  R9: 0000000000000011
   R10: ffffb6a926b79b48 R11: ffff89163fdd5c50 R12: 0000000000000000
   R13: ffff8925b3feb008 R14: ffffb6a91ffb38c0 R15: 000014f54bf47000
   ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
 #7 [ffff958708b57b90] copy_pte_range at ffffffffa4ccf67e
 #8 [ffff958708b57c58] copy_page_range at ffffffffa4cd466d
 #9 [ffff958708b57d70] dup_mm at ffffffffa4aee9f6
#10 [ffff958708b57df0] copy_process at ffffffffa4af0508
#11 [ffff958708b57eb8] _do_fork at ffffffffa4af07fb
#12 [ffff958708b57f38] do_syscall_64 at ffffffffa4a043ab
#13 [ffff958708b57f50] entry_SYSCALL_64_after_hwframe at ffffffffa54000a9