syzbot

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 1bb1c1067 P4D 1bb1c1067 PUD 1d85c3067 PMD 0 
Oops: 0010 [#1] SMP KASAN
CPU: 0 PID: 16432 Comm: syz-executor2 Not tainted 4.18.0+ #201
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:          (null)
Code: Bad RIP value.
RSP: 0018:ffff8801d87969f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc900052fa000
RDX: 1ffff10039871b70 RSI: ffff8801d8796c70 RDI: ffff8801cc38db80
RBP: ffff8801d8796be8 R08: ffff8801d45ca280 R09: 0000000000000003
R10: ffff8801d45cab30 R11: bd9286ea2541144d R12: ffff8801d8796c70
R13: ffff8801cc38db80 R14: ffff8801cc38db80 R15: 0000000000000080
FS:  00007f7b546ab700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001c57d1000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 shrink_slab_memcg mm/vmscan.c:600 [inline]
 shrink_slab+0x7b7/0x990 mm/vmscan.c:673
 shrink_node+0x429/0x16a0 mm/vmscan.c:2734
 shrink_zones mm/vmscan.c:2963 [inline]
 do_try_to_free_pages+0x3e7/0x1290 mm/vmscan.c:3025
 try_to_free_mem_cgroup_pages+0x49d/0xb70 mm/vmscan.c:3323
 memory_high_write+0x283/0x310 mm/memcontrol.c:5399
 cgroup_file_write+0x31f/0x840 kernel/cgroup/cgroup.c:3447
 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
 __vfs_write+0x117/0x9d0 fs/read_write.c:485
 __kernel_write+0x10c/0x380 fs/read_write.c:506
 write_pipe_buf+0x181/0x240 fs/splice.c:798
 splice_from_pipe_feed fs/splice.c:503 [inline]
 __splice_from_pipe+0x38e/0x7c0 fs/splice.c:627
 splice_from_pipe+0x1ea/0x340 fs/splice.c:662
 default_file_splice_write+0x3c/0x90 fs/splice.c:810
 do_splice_from fs/splice.c:852 [inline]
 direct_splice_actor+0x128/0x190 fs/splice.c:1019
 splice_direct_to_actor+0x318/0x8f0 fs/splice.c:974
 do_splice_direct+0x2d4/0x420 fs/splice.c:1062
 do_sendfile+0x623/0xe20 fs/read_write.c:1440
 __do_sys_sendfile64 fs/read_write.c:1501 [inline]
 __se_sys_sendfile64 fs/read_write.c:1487 [inline]
 __x64_sys_sendfile64+0x1fd/0x250 fs/read_write.c:1487
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457089
Code: fd b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7b546aac78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f7b546ab6d4 RCX: 0000000000457089
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d3cb0 R14: 00000000004c8769 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: 0000000000000000
---[ end trace 45c92666fc78c1d3 ]---
RIP: 0010:          (null)
Code: Bad RIP value.
RSP: 0018:ffff8801d87969f8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc900052fa000
RDX: 1ffff10039871b70 RSI: ffff8801d8796c70 RDI: ffff8801cc38db80
RBP: ffff8801d8796be8 R08: ffff8801d45ca280 R09: 0000000000000003
R10: ffff8801d45cab30 R11: bd9286ea2541144d R12: ffff8801d8796c70
R13: ffff8801cc38db80 R14: ffff8801cc38db80 R15: 0000000000000080
FS:  00007f7b546ab700(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001c57d1000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400