BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
PGD 0 P4D 0 
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 4786 Comm: syz-fuzzer Not tainted 4.19.0-rc1+ #41
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kmsan_free_page+0xec/0x2d0 mm/kmsan/kmsan_hooks.c:318
Code: 01 00 00 48 c7 00 00 00 00 00 44 39 e1 0f 8d b0 00 00 00 48 63 d1 48 8d 14 52 48 c1 e2 05 48 8b 54 13 40 48 83 c0 60 83 c1 01 <80> 7a 50 00 74 be 0f 0b 66 90 66 2e 0f 1f 84 00 00 00 00 00 eb fe
RSP: 0018:ffff8801b16cf240 EFLAGS: 00010002
RAX: ffffea0009aef888 RBX: ffffea0009aec000 RCX: 0000000000000097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffffea0001bd8000
RBP: ffff8801b16cf288 R08: 0000000000480020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81c45470 R12: 0000000000000200
R13: ffff88019f833b00 R14: 0000000000000009 R15: ffffea0001b9c000
FS:  000000c4200983e8(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 00000001a23c0000 CR4: 00000000001406f0
Call Trace:
 free_pages_prepare mm/page_alloc.c:994 [inline]
 __free_pages_ok+0x25a/0x16c0 mm/page_alloc.c:1252
 free_compound_page+0x8b/0xc0 mm/page_alloc.c:572
 free_transhuge_page+0x3af/0x460 mm/huge_memory.c:2733
 __put_compound_page mm/swap.c:96 [inline]
 release_pages+0x70c/0x1650 mm/swap.c:760
 free_pages_and_swap_cache+0x54b/0x570 mm/swap_state.c:319
 tlb_flush_mmu_free mm/memory.c:250 [inline]
 tlb_flush_mmu+0x504/0x6b0 mm/memory.c:259
 arch_tlb_finish_mmu mm/memory.c:274 [inline]
 tlb_finish_mmu+0x205/0x420 mm/memory.c:433
 exit_mmap+0x519/0x940 mm/mmap.c:3095
 __mmput+0x154/0x5f0 kernel/fork.c:1003
 mmput+0xa7/0xe0 kernel/fork.c:1024
 exit_mm+0x6dd/0x790 kernel/exit.c:546
 do_exit+0xbf7/0x3890 kernel/exit.c:856
 do_group_exit+0x1a0/0x350 kernel/exit.c:972
 get_signal+0x1425/0x1ef0 kernel/signal.c:2513
 do_signal+0x11d/0x2060 arch/x86/kernel/signal.c:816
 exit_to_usermode_loop arch/x86/entry/common.c:162 [inline]
 prepare_exit_to_usermode+0x273/0x410 arch/x86/entry/common.c:197
 retint_user+0x8/0x8
RIP: 0033:0x41e1a4
Code: Bad RIP value.
RSP: 002b:000000c420061e50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffffda
RAX: 000000c4258ca420 RBX: 00007fbab1a13138 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 00007fbab1b037f8 RDI: 0000000000000001
RBP: 000000c420061e70 R08: 0000000000000021 R09: 0000000000000004
R10: 0000000000000002 R11: 000000c4258ca420 R12: 000000c4327c5800
R13: 000000000000004f R14: 000000000045b6a0 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: 0000000000000050
---[ end trace 57c30151a65fc81b ]---
RIP: 0010:kmsan_free_page+0xec/0x2d0 mm/kmsan/kmsan_hooks.c:318
Code: 01 00 00 48 c7 00 00 00 00 00 44 39 e1 0f 8d b0 00 00 00 48 63 d1 48 8d 14 52 48 c1 e2 05 48 8b 54 13 40 48 83 c0 60 83 c1 01 <80> 7a 50 00 74 be 0f 0b 66 90 66 2e 0f 1f 84 00 00 00 00 00 eb fe
RSP: 0018:ffff8801b16cf240 EFLAGS: 00010002
RAX: ffffea0009aef888 RBX: ffffea0009aec000 RCX: 0000000000000097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: ffffea0001bd8000
RBP: ffff8801b16cf288 R08: 0000000000480020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81c45470 R12: 0000000000000200
R13: ffff88019f833b00 R14: 0000000000000009 R15: ffffea0001b9c000
FS:  000000c4200983e8(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000041e17a CR3: 00000001a23c0000 CR4: 00000000001406f0