[syzbot] [iomap?] [xfs?] WARNING in iomap_write_begin

syzbot
2024-08-13T08:14:24Z

Hello,

syzbot found the following issue on:

HEAD commit: ee9a43b7cfe2 Merge tag 'net-6.11-rc3' of git://git.kernel...
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=10b70c5d980000
kernel config: https://syzkaller.appspot.com/x/.config?x=9358cc4a2e37fd30
dashboard link: https://syzkaller.appspot.com/bug?extid=296b1c84b9cbf306e5a0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=139519d9980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13deb97d980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e6062f24de48/disk-ee9a43b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5d3ec6153dbd/vmlinux-ee9a43b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/98dbabb91d02/bzImage-ee9a43b7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4d05d229907e/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+296b1c84b9cbf306e5a0@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5222 at fs/iomap/buffered-io.c:727 __iomap_write_begin fs/iomap/buffered-io.c:727 [inline]
WARNING: CPU: 1 PID: 5222 at fs/iomap/buffered-io.c:727 iomap_write_begin+0x13f0/0x16f0 fs/iomap/buffered-io.c:830
Modules linked in:
CPU: 1 UID: 0 PID: 5222 Comm: syz-executor247 Not tainted 6.11.0-rc2-syzkaller-00111-gee9a43b7cfe2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:__iomap_write_begin fs/iomap/buffered-io.c:727 [inline]
RIP: 0010:iomap_write_begin+0x13f0/0x16f0 fs/iomap/buffered-io.c:830
Code: b5 0d 01 90 48 c7 c7 a0 54 fa 8b e8 da 19 2b ff 90 0f 0b 90 90 e9 74 ef ff ff e8 5b f1 68 ff e9 4b f6 ff ff e8 51 f1 68 ff 90 <0f> 0b 90 bb fb ff ff ff e9 e9 fe ff ff e8 3e f1 68 ff 90 0f 0b 90
RSP: 0018:ffffc90003a577c0 EFLAGS: 00010293
RAX: ffffffff822a858f RBX: 0000000000000080 RCX: ffff888023080000
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 0000000000000000
RBP: ffffc90003a57a50 R08: ffffffff822a8294 R09: 1ffff11029263f69
R10: dffffc0000000000 R11: ffffed1029263f6a R12: ffffc90003a579b0
R13: ffffc90003a57bf0 R14: ffffc90003a57990 R15: 0000000000000800
FS: 000055555f8fc480(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 0000000079b06000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
iomap_unshare_iter fs/iomap/buffered-io.c:1351 [inline]
iomap_file_unshare+0x460/0x780 fs/iomap/buffered-io.c:1391
xfs_reflink_unshare+0x173/0x5f0 fs/xfs/xfs_reflink.c:1681
xfs_file_fallocate+0x6be/0xa50 fs/xfs/xfs_file.c:997
vfs_fallocate+0x553/0x6c0 fs/open.c:334
ksys_fallocate fs/open.c:357 [inline]
__do_sys_fallocate fs/open.c:365 [inline]
__se_sys_fallocate fs/open.c:363 [inline]
__x64_sys_fallocate+0xbd/0x110 fs/open.c:363
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2d716a6899
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd620c3d18 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2d716a6899
RDX: 0000000000000000 RSI: 0000000000000040 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0700000000000000 R09: 0700000000000000
R10: 0000000000002000 R11: 0000000000000246 R12: 00007ffd620c3d60
R13: 00007ffd620c3fe8 R14: 431bde82d7b634db R15: 00007f2d716ef03b
</TASK>

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup