------------[ cut here ]------------
kernel BUG at fs/ocfs2/refcounttree.c:2890!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5335 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 04/01/2014
RIP: 0010:ocfs2_clear_cow_buffer+0x79/0x80 fs/ocfs2/refcounttree.c:2890
Code: 02 75 21 e8 59 0f fb fd 48 89 df be 08 00 00 00 e8 3c f7 67 fe 3e 80 23 ef 31 c0 5b 41 5e e9 4e b3 e1 07 cc e8 38 0f fb fd 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:ffffc9000365ed58 EFLAGS: 00010287
RAX: ffffffff83cab7d8 RBX: ffff888011f5aae0 RCX: 0000000000100000
RDX: ffffc90021003000 RSI: 00000000000172ef RDI: 00000000000172f0
RBP: 0000000000000001 R08: ffff888011f5aae7 R09: 1ffff110023eb55c
R10: dffffc0000000000 R11: ffffed10023eb55d R12: ffff888011f5aae0
R13: ffff888011f5abc8 R14: 0000000000000002 R15: 0000000000001000
FS:  00007f96b47d36c0(0000) GS:ffff88808c894000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f12ee4305c0 CR3: 0000000040b0c000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 walk_page_buffers+0x94/0x1e0 fs/ocfs2/aops.c:421
 ocfs2_duplicate_clusters_by_page+0x713/0xce0 fs/ocfs2/refcounttree.c:2969
 ocfs2_replace_clusters fs/ocfs2/refcounttree.c:3120 [inline]
 ocfs2_make_clusters_writable fs/ocfs2/refcounttree.c:3252 [inline]
 ocfs2_replace_cow+0xaf6/0x1c90 fs/ocfs2/refcounttree.c:3346
 ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3424 [inline]
 ocfs2_refcount_cow+0x790/0xd40 fs/ocfs2/refcounttree.c:3467
 ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2347 [inline]
 ocfs2_file_write_iter+0xee2/0x1e70 fs/ocfs2/file.c:2458
 iter_file_splice_write+0x9a1/0x10f0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1159
 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1228
 do_sendfile+0x535/0x7d0 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x144/0x1a0 fs/read_write.c:1419
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f96b399ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f96b47d2fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f96b3c16090 RCX: 00007f96b399ce59
RDX: 0000000000000000 RSI: 000000000000000a RDI: 0000000000000009
RBP: 00007f96b3a32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020fffe82 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f96b3c16128 R14: 00007f96b3c16090 R15: 00007ffead92d698
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ocfs2_clear_cow_buffer+0x79/0x80 fs/ocfs2/refcounttree.c:2890
Code: 02 75 21 e8 59 0f fb fd 48 89 df be 08 00 00 00 e8 3c f7 67 fe 3e 80 23 ef 31 c0 5b 41 5e e9 4e b3 e1 07 cc e8 38 0f fb fd 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:ffffc9000365ed58 EFLAGS: 00010287
RAX: ffffffff83cab7d8 RBX: ffff888011f5aae0 RCX: 0000000000100000
RDX: ffffc90021003000 RSI: 00000000000172ef RDI: 00000000000172f0
RBP: 0000000000000001 R08: ffff888011f5aae7 R09: 1ffff110023eb55c
R10: dffffc0000000000 R11: ffffed10023eb55d R12: ffff888011f5aae0
R13: ffff888011f5abc8 R14: 0000000000000002 R15: 0000000000001000
FS:  00007f96b47d36c0(0000) GS:ffff88808c894000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f96a77ff000 CR3: 0000000040b0c000 CR4: 0000000000352ef0