EXT4-fs (sda1): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
EXT4-fs (sda1): warning: refusing change of dax flag with busy inodes while remounting
EXT4-fs (sda1): re-mounted. Opts: dax,
BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
PGD 1d263c067 P4D 1d263c067 PUD 1c52ae067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 19195 Comm: syz-executor1 Not tainted 4.19.0-rc8+ #64
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:          (null)
kobject: 'loop5' (00000000307d4524): kobject_uevent_env
Code: Bad RIP value.
RSP: 0018:ffff88018324f768 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffed0030649f13 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffff8801c3c47470 RDI: ffff8801c3210000
RBP: ffff88018324f900 R08: 0000000000000000 R09: ffff88018324f818
R10: ffffed003b5c4732 R11: ffff8801dae23993 R12: 0000000000000001
R13: 0000000000000001 R14: ffff88017fcf0180 R15: dffffc0000000000
FS:  00007f5da17d4700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
kobject: 'loop5' (00000000307d4524): fill_kobj_path: path = '/devices/virtual/block/loop5'
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001c8c16000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3264
 ext4_file_write_iter+0x390/0x1420 fs/ext4/file.c:266
 call_write_iter include/linux/fs.h:1808 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x6b8/0x9f0 fs/read_write.c:487
 vfs_write+0x1fc/0x560 fs/read_write.c:549
 ksys_write+0x101/0x260 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 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 b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f5da17d3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000000000001 RSI: 0000000020000100 RDI: 0000000000000004
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5da17d46d4
R13: 00000000004c561d R14: 00000000004d8fa0 R15: 00000000ffffffff
Modules linked in:
CR2: 0000000000000000
kobject: 'loop0' (000000001e7edacc): kobject_uevent_env
kobject: 'loop2' (0000000091617ba7): kobject_uevent_env
kobject: 'loop0' (000000001e7edacc): fill_kobj_path: path = '/devices/virtual/block/loop0'
kobject: 'loop2' (0000000091617ba7): fill_kobj_path: path = '/devices/virtual/block/loop2'
---[ end trace 4e7bd45d461b4d26 ]---
RIP: 0010:          (null)
Code: Bad RIP value.
RSP: 0018:ffff88018324f768 EFLAGS: 00010246
kobject: 'loop4' (00000000c94b7f8d): kobject_uevent_env
RAX: 0000000000000000 RBX: ffffed0030649f13 RCX: 0000000000000001
kobject: 'loop4' (00000000c94b7f8d): fill_kobj_path: path = '/devices/virtual/block/loop4'
RDX: 0000000000000000 RSI: ffff8801c3c47470 RDI: ffff8801c3210000
kobject: 'loop5' (00000000307d4524): kobject_uevent_env
kobject: 'loop5' (00000000307d4524): fill_kobj_path: path = '/devices/virtual/block/loop5'
RBP: ffff88018324f900 R08: 0000000000000000 R09: ffff88018324f818
R10: ffffed003b5c4732 R11: ffff8801dae23993 R12: 0000000000000001
R13: 0000000000000001 R14: ffff88017fcf0180 R15: dffffc0000000000
FS:  00007f5da17d4700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop0' (000000001e7edacc): kobject_uevent_env
CR2: 00007f841bdcb4a0 CR3: 00000001c8c16000 CR4: 00000000001406f0
kobject: 'loop0' (000000001e7edacc): fill_kobj_path: path = '/devices/virtual/block/loop0'
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
kobject: 'loop2' (0000000091617ba7): kobject_uevent_env
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
kobject: 'loop2' (0000000091617ba7): fill_kobj_path: path = '/devices/virtual/block/loop2'