BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 638d8067 P4D 638d8067 PUD 668d4067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9000 Comm: syz-executor.1 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:ffffc90000da7418 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff920001b4e8e RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff839dff28 RDI: 0000000000000006
RBP: 0000000000033d7c R08: ffff888064870a80 R09: fffffbfff1516e71
R10: ffffffff8a8b7387 R11: fffffbfff1516e70 R12: 0000000000000040
R13: ffff88801bb23000 R14: 0000000000000247 R15: 000000000000000a
FS:  0000000000000000(0000) GS:ffff88802ce00000(0063) knlGS:00000000f5dd1b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000064015000 CR4: 0000000000340ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 check_preemption_disabled lib/smp_processor_id.c:14 [inline]
 debug_smp_processor_id+0x8/0x185 lib/smp_processor_id.c:57
 balance_dirty_pages_ratelimited+0x3ef/0x1d50 mm/page-writeback.c:1916
 generic_perform_write+0x325/0x4e0 mm/filemap.c:3335
 ext4_buffered_write_iter+0x1f7/0x450 fs/ext4/file.c:270
 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1917 [inline]
 do_iter_readv_writev+0x51e/0x790 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x18b/0x600 fs/read_write.c:980
 vfs_iter_write+0x70/0xa0 fs/read_write.c:1040
 iter_file_splice_write+0x695/0xb10 fs/splice.c:750
 do_splice_from+0x86/0x110 fs/splice.c:846
 direct_splice_actor+0xa3/0x110 fs/splice.c:1016
 splice_direct_to_actor+0x38c/0x980 fs/splice.c:971
 do_splice_direct+0x1b4/0x280 fs/splice.c:1059
 do_sendfile+0x555/0xc50 fs/read_write.c:1521
 __do_compat_sys_sendfile fs/read_write.c:1597 [inline]
 __se_compat_sys_sendfile fs/read_write.c:1586 [inline]
 __ia32_compat_sys_sendfile+0x159/0x220 fs/read_write.c:1586
 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
 do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
Modules linked in:
CR2: 0000000000000000
---[ end trace 4511d5ec68ae2355 ]---
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:ffffc90000da7418 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff920001b4e8e RCX: 0000000000000000
RDX: 0000000000000002 RSI: ffffffff839dff28 RDI: 0000000000000006
RBP: 0000000000033d7c R08: ffff888064870a80 R09: fffffbfff1516e71
R10: ffffffff8a8b7387 R11: fffffbfff1516e70 R12: 0000000000000040
R13: ffff88801bb23000 R14: 0000000000000247 R15: 000000000000000a
FS:  0000000000000000(0000) GS:ffff88802ce00000(0063) knlGS:00000000f5dd1b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000064015000 CR4: 0000000000340ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400