BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 61628067 P4D 61628067 PUD 6161e067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 2 PID: 10342 Comm: syz-executor.3 Not tainted 5.7.0-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x43/0x60 kernel/kcov.c:202
Code: 24 74 0f 80 e6 01 74 35 8b 90 04 14 00 00 85 d2 74 2b 8b 90 e0 13 00 00 83 fa 02 75 20 48 8b 88 e8 13 00 00 8b 80 e4 13 00 00 <48> 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 66 0f
RSP: 0018:ffffc90001777320 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff83899a96 RDI: ffff8880278aa2b0
RBP: ffff8880228c5b00 R08: ffff888061484280 R09: ffffed1005384435
R10: ffff888029c221a7 R11: ffffed1005384434 R12: 0000000000000000
R13: ffff888029c22140 R14: dffffc0000000000 R15: ffff8880228c5b48
FS:  00007fb69bea7700(0000) GS:ffff88802d000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000061626000 CR4: 0000000000340ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 blk_mq_sched_try_insert_merge+0x136/0x160 block/blk-mq-sched.c:406
 dd_insert_request block/mq-deadline.c:496 [inline]
 dd_insert_requests+0x29e/0x970 block/mq-deadline.c:535
 blk_mq_sched_insert_request+0x441/0x660 block/blk-mq-sched.c:487
 blk_mq_make_request+0xdee/0x21d0 block/blk-mq.c:2170
 do_make_request block/blk-core.c:1084 [inline]
 generic_make_request block/blk-core.c:1156 [inline]
 generic_make_request+0xa69/0xc20 block/blk-core.c:1100
 submit_bio+0x11f/0x5b0 block/blk-core.c:1275
 submit_bh_wbc+0x68a/0x8e0 fs/buffer.c:3073
 submit_bh fs/buffer.c:3079 [inline]
 __sync_dirty_buffer+0x11f/0x360 fs/buffer.c:3165
 ext4_write_inode+0x4eb/0x5a0 fs/ext4/inode.c:5143
 write_inode fs/fs-writeback.c:1311 [inline]
 __writeback_single_inode+0xd69/0x1410 fs/fs-writeback.c:1510
 writeback_single_inode+0x2ae/0x410 fs/fs-writeback.c:1564
 sync_inode fs/fs-writeback.c:2601 [inline]
 sync_inode_metadata+0x93/0xd0 fs/fs-writeback.c:2621
 ext4_fsync_nojournal fs/ext4/fsync.c:94 [inline]
 ext4_sync_file+0x7e4/0x10d0 fs/ext4/fsync.c:172
 vfs_fsync_range+0x138/0x220 fs/sync.c:199
 generic_write_sync include/linux/fs.h:2894 [inline]
 ext4_buffered_write_iter+0x2fd/0x450 fs/ext4/file.c:277
 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1917 [inline]
 new_sync_write+0x426/0x650 fs/read_write.c:484
 __vfs_write+0xc9/0x100 fs/read_write.c:497
 vfs_write+0x268/0x5d0 fs/read_write.c:559
 ksys_write+0x12d/0x250 fs/read_write.c:612
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c879
Code: 1d b2 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 eb b1 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb69bea6c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000074bf00 RCX: 000000000045c879
RDX: 0000000000000216 RSI: 0000000020000040 RDI: 0000000000000006
RBP: 000000000071ec40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb69bea76d4
R13: 0000000000000c79 R14: 00000000006ece00 R15: 00000000004b1252
Modules linked in:
CR2: 0000000000000000
---[ end trace 88e03f0d70c93b3b ]---
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x43/0x60 kernel/kcov.c:202
Code: 24 74 0f 80 e6 01 74 35 8b 90 04 14 00 00 85 d2 74 2b 8b 90 e0 13 00 00 83 fa 02 75 20 48 8b 88 e8 13 00 00 8b 80 e4 13 00 00 <48> 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 66 0f
RSP: 0018:ffffc90001777320 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff83899a96 RDI: ffff8880278aa2b0
RBP: ffff8880228c5b00 R08: ffff888061484280 R09: ffffed1005384435
R10: ffff888029c221a7 R11: ffffed1005384434 R12: 0000000000000000
R13: ffff888029c22140 R14: dffffc0000000000 R15: ffff8880228c5b48
FS:  00007fb69bea7700(0000) GS:ffff88802d000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000061626000 CR4: 0000000000340ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400