syzbot

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kernel BUG at fs/ocfs2/refcounttree.c:2891!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5348 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ocfs2_clear_cow_buffer+0x79/0x80 fs/ocfs2/refcounttree.c:2891
Code: 02 75 21 e8 39 93 12 fe 48 89 df be 08 00 00 00 e8 6c 40 7a fe 3e 80 23 ef 31 c0 5b 41 5e c3 cc cc cc cc cc e8 18 93 12 fe 90 <0f> 0b 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000d667198 EFLAGS: 00010287
RAX: ffffffff83ae7448 RBX: ffff888046e749f8 RCX: 0000000000100000
RDX: ffffc90021a23000 RSI: 0000000000004de0 RDI: 0000000000004de1
RBP: 0000000000000001 R08: ffff888046e749ff R09: 1ffff11008dce93f
R10: dffffc0000000000 R11: ffffed1008dce940 R12: ffff888046e749f8
R13: ffff888046e74910 R14: 0000000000000002 R15: 0000000000001000
FS:  00007f57f783f6c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f57f783efc8 CR3: 000000004137b000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 walk_page_buffers+0x94/0x1e0 fs/ocfs2/aops.c:419
 ocfs2_duplicate_clusters_by_page+0x726/0xc90 fs/ocfs2/refcounttree.c:2970
 __ocfs2_move_extent+0x238/0xd50 fs/ocfs2/move_extents.c:63
 ocfs2_move_extent fs/ocfs2/move_extents.c:678 [inline]
 __ocfs2_move_extents_range fs/ocfs2/move_extents.c:865 [inline]
 ocfs2_move_extents+0x2337/0x3dd0 fs/ocfs2/move_extents.c:937
 ocfs2_ioctl_move_extents+0x568/0x740 fs/ocfs2/move_extents.c:1069
 ocfs2_ioctl+0x191/0x750 fs/ocfs2/ioctl.c:942
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f57f698f7c9
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:00007f57f783f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f57f6be6180 RCX: 00007f57f698f7c9
RDX: 00002000000000c0 RSI: 0000000040406f06 RDI: 0000000000000006
RBP: 00007f57f6a13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f57f6be6218 R14: 00007f57f6be6180 R15: 00007ffef434d268
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ocfs2_clear_cow_buffer+0x79/0x80 fs/ocfs2/refcounttree.c:2891
Code: 02 75 21 e8 39 93 12 fe 48 89 df be 08 00 00 00 e8 6c 40 7a fe 3e 80 23 ef 31 c0 5b 41 5e c3 cc cc cc cc cc e8 18 93 12 fe 90 <0f> 0b 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000d667198 EFLAGS: 00010287
RAX: ffffffff83ae7448 RBX: ffff888046e749f8 RCX: 0000000000100000
RDX: ffffc90021a23000 RSI: 0000000000004de0 RDI: 0000000000004de1
RBP: 0000000000000001 R08: ffff888046e749ff R09: 1ffff11008dce93f
R10: dffffc0000000000 R11: ffffed1008dce940 R12: ffff888046e749f8
R13: ffff888046e74910 R14: 0000000000000002 R15: 0000000000001000
FS:  00007f57f783f6c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f978f450550 CR3: 000000004137b000 CR4: 0000000000352ef0