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Date: Thu, 22 Feb 2024 18:03:22 -0800
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Subject: [syzbot] [btrfs?] WARNING in btrfs_get_root_ref
From: syzbot <syzbot+623a623cfed57f422be1@syzkaller.appspotmail.com>
To: clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, 
	linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, 
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    c02197fc9076 Merge tag 'powerpc-6.8-3' of git://git.kernel..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16765b8a180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caa42dd2796e3ac1
dashboard link: https://syzkaller.appspot.com/bug?extid=623a623cfed57f422be1
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7b2a3f729cc3/disk-c02197fc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b4f10e6eb1ca/vmlinux-c02197fc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8488781d739e/bzImage-c02197fc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+623a623cfed57f422be1@syzkaller.appspotmail.com

------------[ cut here ]------------
ida_free called for id=51 which is not allocated.
WARNING: CPU: 1 PID: 31038 at lib/idr.c:525 ida_free+0x370/0x420 lib/idr.c:525
Modules linked in:
CPU: 1 PID: 31038 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00410-gc02197fc9076 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:ida_free+0x370/0x420 lib/idr.c:525
Code: 10 42 80 3c 28 00 74 05 e8 6d a3 9b f6 48 8b 7c 24 40 4c 89 fe e8 a0 89 17 00 90 48 c7 c7 00 ca c5 8c 89 de e8 01 91 fd f5 90 <0f> 0b 90 90 eb 3d e8 e5 85 39 f6 49 bd 00 00 00 00 00 fc ff df 4d
RSP: 0018:ffffc90015a67300 EFLAGS: 00010246
RAX: be5130472f5dd000 RBX: 0000000000000033 RCX: 0000000000040000
RDX: ffffc90009a7a000 RSI: 000000000003ffff RDI: 0000000000040000
RBP: ffffc90015a673f0 R08: ffffffff81577992 R09: 1ffff92002b4cdb4
R10: dffffc0000000000 R11: fffff52002b4cdb5 R12: 0000000000000246
R13: dffffc0000000000 R14: ffffffff8e256b80 R15: 0000000000000246
FS:  00007fca3f4b46c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f167a17b978 CR3: 000000001ed26000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 btrfs_get_root_ref+0xa48/0xaf0 fs/btrfs/disk-io.c:1346
 create_pending_snapshot+0xff2/0x2bc0 fs/btrfs/transaction.c:1837
 create_pending_snapshots+0x195/0x1d0 fs/btrfs/transaction.c:1931
 btrfs_commit_transaction+0xf1c/0x3740 fs/btrfs/transaction.c:2404
 create_snapshot+0x507/0x880 fs/btrfs/ioctl.c:848
 btrfs_mksubvol+0x5d0/0x750 fs/btrfs/ioctl.c:998
 btrfs_mksnapshot+0xb5/0xf0 fs/btrfs/ioctl.c:1044
 __btrfs_ioctl_snap_create+0x387/0x4b0 fs/btrfs/ioctl.c:1306
 btrfs_ioctl_snap_create_v2+0x1ca/0x400 fs/btrfs/ioctl.c:1393
 btrfs_ioctl+0xa74/0xd40
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfe/0x170 fs/ioctl.c:857
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7fca3e67dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fca3f4b40c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fca3e7abf80 RCX: 00007fca3e67dda9
RDX: 00000000200005c0 RSI: 0000000050009417 RDI: 0000000000000003
RBP: 00007fca3e6ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fca3e7abf80 R15: 00007fff6bf95658
 </TASK>


---
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