BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 947f0067 P4D 947f0067 PUD 95e0c067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 19362 Comm: syz-executor.3 Not tainted 5.7.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90005487980 EFLAGS: 00010246
RAX: ffffffff839f8305 RBX: ffffea0001d83eb4 RCX: ffff888062e060c0
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff819988b3
RBP: 0000000000000081 R08: dffffc0000000000 R09: fffff940003b07d7
R10: fffff940003b07d7 R11: 0000000000000000 R12: ffffea0001d83e80
R13: dffffc0000000000 R14: 1ffffd40003b07d1 R15: ffffea0001d83e80
FS:  00007f797055e700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000097c56000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 debug_smp_processor_id+0x5/0x20 lib/smp_processor_id.c:56
 lru_cache_add+0x268/0x640 mm/swap.c:471
 add_to_page_cache_lru+0x307/0x4d0 mm/filemap.c:934
 pagecache_get_page+0x784/0xd00 mm/filemap.c:1653
 grab_cache_page_write_begin+0x50/0x90 mm/filemap.c:3249
 ext4_da_write_begin+0x4b9/0xf80 fs/ext4/inode.c:2964
 generic_perform_write+0x23b/0x4e0 mm/filemap.c:3299
 ext4_buffered_write_iter+0x44d/0x5d0 fs/ext4/file.c:270
 ext4_file_write_iter+0x6c1/0x1840 fs/ext4/file.c:491
 call_write_iter include/linux/fs.h:1917 [inline]
 new_sync_write fs/read_write.c:484 [inline]
 __vfs_write+0x52f/0x6e0 fs/read_write.c:497
 vfs_write+0x274/0x580 fs/read_write.c:559
 ksys_write+0x11b/0x220 fs/read_write.c:612
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45ca59
Code: 0d b7 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f797055dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050d560 RCX: 000000000045ca59
RDX: 0000000000400086 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d0e R14: 00000000004cf64a R15: 00007f797055e6d4
Modules linked in:
CR2: 0000000000000000
---[ end trace 625b36ad189c07d3 ]---
RIP: 0010:__read_once_size include/linux/compiler.h:252 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x60 kernel/kcov.c:202
Code: c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 04 14 00 00 00 74 2c 8b 91 e0 13 00 00 83 fa 02 75 21 48 8b 91 e8 13 00 00 <48> 8b 32 48 8d 7e 01 8b 89 e4 13 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0018:ffffc90005487980 EFLAGS: 00010246
RAX: ffffffff839f8305 RBX: ffffea0001d83eb4 RCX: ffff888062e060c0
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff819988b3
RBP: 0000000000000081 R08: dffffc0000000000 R09: fffff940003b07d7
R10: fffff940003b07d7 R11: 0000000000000000 R12: ffffea0001d83e80
R13: dffffc0000000000 R14: 1ffffd40003b07d1 R15: ffffea0001d83e80
FS:  00007f797055e700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000097c56000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400