BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 1f31f5067 P4D 1f31f5067 PUD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 3566 Comm: syz.4.1062 Tainted: G        W         5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010206
RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881d1dacec0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881ed7471c0
RBP: ffff8881f6f09d30 R08: 0000000000000004 R09: 0000000000000003
R10: ffffed103ede1398 R11: 1ffff1103ede1398 R12: 00000000ffffbb48
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881ed7471c0
FS:  00007f27be6c06c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001ed631000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 call_timer_fn+0x3c/0x380 kernel/time/timer.c:1448
 expire_timers kernel/time/timer.c:1493 [inline]
 __run_timers+0x81d/0xb60 kernel/time/timer.c:1817
 run_timer_softirq+0x6a/0xf0 kernel/time/timer.c:1830
 __do_softirq+0x236/0x660 kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x197/0x1c0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:539 [inline]
 smp_apic_timer_interrupt+0x11d/0x490 arch/x86/kernel/apic/apic.c:1161
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:834
 </IRQ>
RIP: 0010:find_get_entry+0x47/0x3c0 mm/filemap.c:1684
Code: fe 65 48 8b 04 25 28 00 00 00 48 89 84 24 a0 00 00 00 48 bb 00 00 00 00 00 fc ff df 4c 8d 64 24 50 48 c7 44 24 20 b3 8a b5 41 <48> c7 44 24 28 52 4b 3f 85 48 c7 44 24 30 70 b7 79 81 48 8d 4c 24
RSP: 0018:ffff8881e921f640 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: b71092cfe2427d00 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000354e000 RSI: 0000000000000039 RDI: ffff8881ea1b48d0
RBP: ffff8881e921f728 R08: 0000000000100cca R09: 0000000000000000
R10: ffffed103a3b59d9 R11: 1ffff1103a3b59d8 R12: ffff8881e921f690
R13: 0000000000000000 R14: ffff8881ea1b48d0 R15: 0000000000000039
 find_lock_entry+0x2b/0x1f0 mm/filemap.c:1742
 shmem_getpage_gfp+0x3c3/0x2370 mm/shmem.c:1775
 shmem_getpage mm/shmem.c:154 [inline]
 shmem_write_begin+0xce/0x1b0 mm/shmem.c:2447
 generic_perform_write+0x2b8/0x500 mm/filemap.c:3450
 __generic_file_write_iter+0x24b/0x480 mm/filemap.c:3579
 generic_file_write_iter+0x48d/0x620 mm/filemap.c:3611
 call_write_iter include/linux/fs.h:1991 [inline]
 new_sync_write fs/read_write.c:483 [inline]
 __vfs_write+0x480/0x5d0 fs/read_write.c:496
 vfs_write+0x20e/0x4c0 fs/read_write.c:558
 ksys_write+0x140/0x240 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:620
 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x5c/0xc1
RIP: 0033:0x7f27c0057969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f27be6c0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f27c027efa0 RCX: 00007f27c0057969
RDX: 000000011ffffce1 RSI: 0000200000000080 RDI: 0000000000000006
RBP: 00007f27c00d9ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f27c027efa0 R15: 00007fff41be5478
Modules linked in:
CR2: 0000000000000000
---[ end trace b1b842d3f232a6f5 ]---
RIP: 0010:0x0
Code: Bad RIP value.
RSP: 0018:ffff8881f6f09cf0 EFLAGS: 00010206
RAX: ffffffff8150a590 RBX: 0000000000000100 RCX: ffff8881d1dacec0
RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffff8881ed7471c0
RBP: ffff8881f6f09d30 R08: 0000000000000004 R09: 0000000000000003
R10: ffffed103ede1398 R11: 1ffff1103ede1398 R12: 00000000ffffbb48
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8881ed7471c0
FS:  00007f27be6c06c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001ed631000 CR4: 00000000003406a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	65 48 8b 04 25 28 00 	mov    %gs:0x28,%rax
   7:	00 00
   9:	48 89 84 24 a0 00 00 	mov    %rax,0xa0(%rsp)
  10:	00
  11:	48 bb 00 00 00 00 00 	movabs $0xdffffc0000000000,%rbx
  18:	fc ff df
  1b:	4c 8d 64 24 50       	lea    0x50(%rsp),%r12
  20:	48 c7 44 24 20 b3 8a 	movq   $0x41b58ab3,0x20(%rsp)
  27:	b5 41
* 29:	48 c7 44 24 28 52 4b 	movq   $0xffffffff853f4b52,0x28(%rsp) <-- trapping instruction
  30:	3f 85
  32:	48 c7 44 24 30 70 b7 	movq   $0xffffffff8179b770,0x30(%rsp)
  39:	79 81
  3b:	48                   	rex.W
  3c:	8d                   	.byte 0x8d
  3d:	4c                   	rex.WR
  3e:	24                   	.byte 0x24