Re: [syzbot] [btrfs?] possible deadlock in set_blocksize

From: syzbot

Date: Wed Oct 28 2026 - 09:04:16 EST


Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in __btrfs_free_extent

------------[ cut here ]------------
ret == -E
ret == -ENOENT
WARNING: fs/btrfs/extent-tree.c:3418 at __btrfs_free_extent+0x1745/0x38a0 fs/btrfs/extent-tree.c:3418, CPU#1: btrfs-transacti/6038
Modules linked in:
CPU: 1 UID: 0 PID: 6038 Comm: btrfs-transacti Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
RIP: 0010:__btrfs_free_extent+0x1745/0x38a0 fs/btrfs/extent-tree.c:3418
Code: 84 c0 0f 84 01 03 00 00 e8 d8 88 a8 fd e9 30 0b 00 00 e8 1e ef 8c fd 84 c0 0f 84 0c 03 00 00 e8 c1 88 a8 fd e9 9d 0c 00 00 90 <0f> 0b 90 48 8b 44 24 28 42 80 3c 20 00 4d 8d 75 60 74 08 4c 89 f7
RSP: 0018:ffffc900034d7580 EFLAGS: 00010246
RAX: 00000000fffffffe RBX: ffff88801faee720 RCX: 0000000000000005
RDX: ffffffff8420790e RSI: ffffffff905d9c00 RDI: 00000000fffffffe
RBP: ffffc900034d7730 R08: ffff888021381f40 R09: 0000000000000002
R10: 00000000fffffffe R11: 0000000000000000 R12: dffffc0000000000
R13: ffff88805ad54178 R14: ffff888053e7ddc0 R15: 00000000fffffffe
FS: 0000000000000000(0000) GS:ffff88812372b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560567923d51 CR3: 000000007caed000 CR4: 0000000000350ef0
Call Trace:
<TASK>
run_delayed_tree_ref fs/btrfs/extent-tree.c:1824 [inline]
run_one_delayed_ref fs/btrfs/extent-tree.c:1851 [inline]
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:2058 [inline]
__btrfs_run_delayed_refs+0x1669/0x43a0 fs/btrfs/extent-tree.c:2134
btrfs_run_delayed_refs+0xdc/0x2a0 fs/btrfs/extent-tree.c:2246
btrfs_commit_transaction+0x287/0x3010 fs/btrfs/transaction.c:2283
transaction_kthread+0x2c1/0x460 fs/btrfs/disk-io.c:1586
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


Tested on:

commit: 65ba8f34 Merge tag 'xtensa-20261027' of https://github..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1439e469580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fbcd9c8641bd149b
dashboard link: https://syzkaller.appspot.com/bug?extid=5c01398781fb51df783a
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=11607721580000