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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: 5334 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:2891
Code: 02 75 21 e8 a9 a7 fe fd 48 89 df be 08 00 00 00 e8 5c 85 6a fe 3e 80 23 ef 31 c0 5b 41 5e c3 cc cc cc cc cc e8 88 a7 fe 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:ffffc9000df2ed78 EFLAGS: 00010287
RAX: ffffffff83c71708 RBX: ffff88801f428cb0 RCX: 0000000000100000
RDX: ffffc90020001000 RSI: 000000000002b746 RDI: 000000000002b747
RBP: 0000000000000001 R08: ffff88801f428cb7 R09: 1ffff11003e85196
R10: dffffc0000000000 R11: ffffed1003e85197 R12: ffff88801f428cb0
R13: ffff88801f428d98 R14: 0000000000000002 R15: 0000000000001000
FS:  00007fbbf1c596c0(0000) GS:ffff88808ca4c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002500 CR3: 000000001abe5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 walk_page_buffers+0x94/0x1e0 fs/ocfs2/aops.c:419
 ocfs2_duplicate_clusters_by_page+0x713/0xce0 fs/ocfs2/refcounttree.c:2970
 ocfs2_replace_clusters fs/ocfs2/refcounttree.c:3121 [inline]
 ocfs2_make_clusters_writable fs/ocfs2/refcounttree.c:3253 [inline]
 ocfs2_replace_cow+0xaeb/0x1ce0 fs/ocfs2/refcounttree.c:3347
 ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3425 [inline]
 ocfs2_refcount_cow+0x7ad/0xd80 fs/ocfs2/refcounttree.c:3468
 ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2347 [inline]
 ocfs2_file_write_iter+0xee2/0x1ed0 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+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbbf0d9c819
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:00007fbbf1c58fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007fbbf1016090 RCX: 00007fbbf0d9c819
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 0000000000000009
RBP: 00007fbbf0e32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0001000200201005 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbbf1016128 R14: 00007fbbf1016090 R15: 00007ffe30dcc9e8
 </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 a9 a7 fe fd 48 89 df be 08 00 00 00 e8 5c 85 6a fe 3e 80 23 ef 31 c0 5b 41 5e c3 cc cc cc cc cc e8 88 a7 fe 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:ffffc9000df2ed78 EFLAGS: 00010287
RAX: ffffffff83c71708 RBX: ffff88801f428cb0 RCX: 0000000000100000
RDX: ffffc90020001000 RSI: 000000000002b746 RDI: 000000000002b747
RBP: 0000000000000001 R08: ffff88801f428cb7 R09: 1ffff11003e85196
R10: dffffc0000000000 R11: ffffed1003e85197 R12: ffff88801f428cb0
R13: ffff88801f428d98 R14: 0000000000000002 R15: 0000000000001000
FS:  00007fbbf1c596c0(0000) GS:ffff88808ca4c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002500 CR3: 000000001abe5000 CR4: 0000000000352ef0