------------[ cut here ]------------
WARNING: CPU: 1 PID: 2235 at kernel/rcu/tree_stall.h:894 rcu_check_gp_start_stall.part.0+0x325/0x4b0 kernel/rcu/tree_stall.h:886
Modules linked in:
CPU: 1 PID: 2235 Comm: syz-executor.2 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rcu_check_gp_start_stall.part.0+0x325/0x4b0 kernel/rcu/tree_stall.h:894
Code: 0f 88 fa 00 00 00 be 04 00 00 00 48 c7 c7 a0 55 22 90 e8 2e 39 5a 00 b8 01 00 00 00 87 05 23 a8 c0 0e 85 c0 0f 85 c9 00 00 00 <0f> 0b 48 81 fd c0 50 98 8b 48 c7 c3 6c b5 6c 8d 74 58 48 b8 00 00
RSP: 0018:ffffc90000dc0e30 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 000000010003244d RCX: ffffffff8161ad72
RDX: fffffbfff2044ab4 RSI: 0000000000000004 RDI: ffffffff902255a0
RBP: ffffffff8b9850c0 R08: 0000000000000001 R09: 0000000000000003
R10: fffffbfff2044ab4 R11: 1ffff110173aa54e R12: 1ffffffff16c1e30
R13: 0000000000000246 R14: ffff8880b9d52992 R15: 0000000000000001
FS:  00007f9d367d5700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005f8dd000 CR4: 00000000001506e0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 rcu_check_gp_start_stall kernel/rcu/tree_stall.h:857 [inline]
 rcu_core+0x4df/0x1380 kernel/rcu/tree.c:2780
 __do_softirq+0x29b/0x9c2 kernel/softirq.c:558
 invoke_softirq kernel/softirq.c:432 [inline]
 __irq_exit_rcu+0x16e/0x1c0 kernel/softirq.c:636
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:648
 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:preempt_schedule_irq+0x49/0x90 kernel/sched/core.c:6326
Code: 55 53 65 48 8b 1c 25 40 f0 01 00 48 89 dd 48 c1 ed 03 48 01 c5 bf 01 00 00 00 e8 02 80 23 f8 e8 1d cc 4f f8 fb bf 01 00 00 00 <e8> d2 cd ff ff 9c 58 fa f6 c4 02 75 27 bf 01 00 00 00 e8 10 6f 23
RSP: 0018:ffffc90001d9f548 EFLAGS: 00000202
RAX: 0000000000002529 RBX: ffff888029d80000 RCX: 1ffffffff1fa1dc2
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: ffffed10053b0000 R08: 0000000000000001 R09: ffffffff8fcd597f
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 irqentry_exit+0x31/0x80 kernel/entry/common.c:427
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:page_is_mergeable block/bio.c:707 [inline]
RIP: 0010:__bio_try_merge_page+0x243/0x360 block/bio.c:868
Code: 83 e6 07 40 38 f2 7f 08 84 d2 0f 85 f2 00 00 00 48 8b 3c 24 48 89 c6 41 88 4d 00 48 89 44 24 10 e8 82 19 b7 fd 48 8b 44 24 10 <48> 39 04 24 74 2a e8 a2 13 b7 fd 48 8b 44 24 08 41 c1 ec 0c 49 c1
RSP: 0018:ffffc90001d9f618 EFLAGS: 00000246
RAX: 00000000973ad000 RBX: ffff88808ddff640 RCX: 00000000973ad000
RDX: 0000000000000000 RSI: ffff888029d80000 RDI: 0000000000000003
RBP: ffff88808bc16600 R08: 00000000973ae000 R09: 0000000000000001
R10: ffffffff83be953e R11: 0000000000000000 R12: 0000000000000000
R13: ffffc90001d9f718 R14: ffffea00025ceb80 R15: 0000000000001000
 __bio_iov_iter_get_pages block/bio.c:1022 [inline]
 bio_iov_iter_get_pages block/bio.c:1121 [inline]
 bio_iov_iter_get_pages+0x2e7/0x1430 block/bio.c:1107
 iomap_dio_bio_actor+0x7fd/0x1090 fs/iomap/direct-io.c:317
 iomap_dio_actor+0x89/0x550 fs/iomap/direct-io.c:419
 iomap_apply+0x2a3/0xb50 fs/iomap/apply.c:84
 __iomap_dio_rw+0x725/0x1300 fs/iomap/direct-io.c:561
 iomap_dio_rw+0x30/0x90 fs/iomap/direct-io.c:649
 ext4_dio_write_iter fs/ext4/file.c:568 [inline]
 ext4_file_write_iter+0xe18/0x14e0 fs/ext4/file.c:678
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write+0x426/0x650 fs/read_write.c:518
 vfs_write+0x75a/0xa40 fs/read_write.c:605
 ksys_write+0x12d/0x250 fs/read_write.c:658
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9d367d5188 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665f9
RDX: 0000000000806000 RSI: 0000000020000200 RDI: 0000000000000005
RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffea035e07f R14: 00007f9d367d5300 R15: 0000000000022000
----------------
Code disassembly (best guess):
   0:	55                   	push   %rbp
   1:	53                   	push   %rbx
   2:	65 48 8b 1c 25 40 f0 	mov    %gs:0x1f040,%rbx
   9:	01 00
   b:	48 89 dd             	mov    %rbx,%rbp
   e:	48 c1 ed 03          	shr    $0x3,%rbp
  12:	48 01 c5             	add    %rax,%rbp
  15:	bf 01 00 00 00       	mov    $0x1,%edi
  1a:	e8 02 80 23 f8       	callq  0xf8238021
  1f:	e8 1d cc 4f f8       	callq  0xf84fcc41
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 d2 cd ff ff       	callq  0xffffce01 <-- trapping instruction
  2f:	9c                   	pushfq
  30:	58                   	pop    %rax
  31:	fa                   	cli
  32:	f6 c4 02             	test   $0x2,%ah
  35:	75 27                	jne    0x5e
  37:	bf 01 00 00 00       	mov    $0x1,%edi
  3c:	e8                   	.byte 0xe8
  3d:	10 6f 23             	adc    %ch,0x23(%rdi)