[syzbot] [btrfs?] kernel BUG in btrfs_subpage_assert

[syzbot <syzbot+d490d04560554e6259b9@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    a4ff2be345d0 Merge tag 'v7.3-p1' of git://git.kernel.org/p..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e1f815580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cfcda1d4ca446c80
dashboard link: https://syzkaller.appspot.com/bug?extid=d490d04560554e6259b9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-a4ff2be3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0a03ffb73f4e/vmlinux-a4ff2be3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/27503648559b/bzImage-a4ff2be3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d490d04560554e6259b9@syzkaller.appspotmail.com

assertion failed: folio_test_private(folio) && folio_get_private(folio), in fs/btrfs/subpage.c:153
------------[ cut here ]------------
kernel BUG at fs/btrfs/subpage.c:153!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5316 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:btrfs_subpage_assert+0x43f/0x4e0 fs/btrfs/subpage.c:153
Code: ae 8b fd eb 05 e8 e1 ae 8b fd 48 c7 c7 80 4d 3b 8c 48 c7 c6 20 53 3b 8c 48 c7 c2 20 4e 3b 8c b9 99 00 00 00 e8 f2 53 ec fc 90 <0f> 0b e8 ba ae 8b fd 4c 89 ff 48 c7 c6 80 54 3b 8c e8 eb b2 ec fc
RSP: 0018:ffffc9000e34f438 EFLAGS: 00010246
RAX: 0000000000000062 RBX: 0000000000000000 RCX: 8237ef3e22428900
RDX: ffffc90020001000 RSI: 00000000000fffff RDI: 0000000000100000
RBP: ffffea000039f800 R08: ffffc9000e34f1c7 R09: 1ffff92001c69e38
R10: dffffc0000000000 R11: fffff52001c69e39 R12: 1ffffd4000073f01
R13: ffff88804340c000 R14: 1ffffd4000073f00 R15: ffffea000039f800
FS:  00007fc1fc8ed6c0(0000) GS:ffff88808c526000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8aebf44cf0 CR3: 0000000012f73000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 btrfs_subpage_set_fixup_dirty fs/btrfs/subpage.c:528 [inline]
 btrfs_folio_set_fixup_dirty+0x475/0xc70 fs/btrfs/subpage.c:567
 btrfs_data_dirty_folio+0x1c7/0x240 fs/btrfs/inode.c:10763
 bio_set_pages_dirty+0x372/0xa70 block/bio.c:1681
 __blkdev_direct_IO+0x81f/0xf30 block/fops.c:247
 blkdev_direct_IO+0x122e/0x17a0 block/fops.c:435
 blkdev_read_iter+0x223/0x420 block/fops.c:816
 aio_read+0x33a/0x4d0 fs/aio.c:1656
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0x774/0x13d0 fs/aio.c:2106
 __do_sys_io_submit fs/aio.c:2165 [inline]
 __se_sys_io_submit+0x195/0x340 fs/aio.c:2135
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc1fb99e0d9
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:00007fc1fc8ecfe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007fc1fbc26090 RCX: 00007fc1fb99e0d9
RDX: 00002000000000c0 RSI: 00000000000000ca RDI: 00007fc1fc8cc000
RBP: 00007fc1fba35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc1fbc26128 R14: 00007fc1fbc26090 R15: 00007ffeb5334bc8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btrfs_subpage_assert+0x43f/0x4e0 fs/btrfs/subpage.c:153
Code: ae 8b fd eb 05 e8 e1 ae 8b fd 48 c7 c7 80 4d 3b 8c 48 c7 c6 20 53 3b 8c 48 c7 c2 20 4e 3b 8c b9 99 00 00 00 e8 f2 53 ec fc 90 <0f> 0b e8 ba ae 8b fd 4c 89 ff 48 c7 c6 80 54 3b 8c e8 eb b2 ec fc
RSP: 0018:ffffc9000e34f438 EFLAGS: 00010246
RAX: 0000000000000062 RBX: 0000000000000000 RCX: 8237ef3e22428900
RDX: ffffc90020001000 RSI: 00000000000fffff RDI: 0000000000100000
RBP: ffffea000039f800 R08: ffffc9000e34f1c7 R09: 1ffff92001c69e38
R10: dffffc0000000000 R11: fffff52001c69e39 R12: 1ffffd4000073f01
R13: ffff88804340c000 R14: 1ffffd4000073f00 R15: ffffea000039f800
FS:  00007fc1fc8ed6c0(0000) GS:ffff88808c526000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc9601fb6b0 CR3: 0000000012f73000 CR4: 0000000000352ef0


---
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 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