syzbot


possible deadlock in unix_collect_skb

Status: upstream: reported C repro on 2025/07/06 13:45
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+935eda0926f44898461e@syzkaller.appspotmail.com
First crash: 210d, last: 4d16h
Bug presence (2)
Date Name Commit Repro Result
2026/01/25 linux-6.1.y (ToT) cd9b81672742 C [report] possible deadlock in unix_collect_skb
2026/01/25 upstream (ToT) 913fb068e259 C Didn't crash
Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/01/25 19:38 1m fix candidate upstream error job log
2025/09/27 23:42 2h49m fix candidate upstream OK (0) job log
2025/07/25 07:11 16m fix candidate upstream error job log

Sample crash report:
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/u4:4/75 is trying to acquire lock:
ffff88801e7299e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88801e7299e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: unix_collect_skb+0x15a/0x550 net/unix/garbage.c:363

but task is already holding lock:
ffff88801e7289e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88801e7289e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: unix_collect_skb+0xb7/0x550 net/unix/garbage.c:355

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(rlock-AF_UNIX);
  lock(rlock-AF_UNIX);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by kworker/u4:4/75:
 #0: ffff888017479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #1: ffffc90001597d00 (unix_gc_work){+.+.}-{0:0}, at: process_one_work+0x7b0/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8de46078 (unix_gc_lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #2: ffffffff8de46078 (unix_gc_lock){+.+.}-{2:2}, at: __unix_gc+0xc4/0x19b0 net/unix/garbage.c:563
 #3: ffff88801e7289e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #3: ffff88801e7289e8 (rlock-AF_UNIX){+.+.}-{2:2}, at: unix_collect_skb+0xb7/0x550 net/unix/garbage.c:355

stack backtrace:
CPU: 0 PID: 75 Comm: kworker/u4:4 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_unbound __unix_gc
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 __lock_acquire+0x123e/0x7d10 kernel/locking/lockdep.c:-1
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 unix_collect_skb+0x15a/0x550 net/unix/garbage.c:363
 __unix_walk_scc net/unix/garbage.c:486 [inline]
 unix_walk_scc net/unix/garbage.c:517 [inline]
 __unix_gc+0x1107/0x19b0 net/unix/garbage.c:575
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (377):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/25 15:40 linux-6.1.y cd9b81672742 40acda8a .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/10/17 08:58 linux-6.1.y c2fda4b3f577 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/07/06 22:56 linux-6.1.y 04d1ccaa9c28 4f67c4ae .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/28 18:17 linux-6.1.y cd9b81672742 004c195c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/26 08:55 linux-6.1.y cd9b81672742 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/25 18:12 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/25 14:55 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/24 21:22 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/23 19:09 linux-6.1.y cd9b81672742 e2b1b6e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/14 18:12 linux-6.1.y bec0e10ee67e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/05 14:16 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/05 01:39 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/04 13:23 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/03 14:52 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/03 01:21 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/02 15:42 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/01 15:13 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/31 03:04 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/26 05:39 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/25 06:03 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/20 11:36 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/17 04:12 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/16 08:03 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/16 06:59 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/15 12:33 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/12 20:54 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/11 20:03 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/12/08 11:49 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2025/07/06 13:45 linux-6.1.y 04d1ccaa9c28 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in unix_collect_skb
2026/01/28 16:23 linux-6.1.y cd9b81672742 004c195c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/26 16:50 linux-6.1.y cd9b81672742 a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/26 06:07 linux-6.1.y cd9b81672742 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/25 17:08 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/25 07:13 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/24 17:58 linux-6.1.y cd9b81672742 40acda8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/23 17:58 linux-6.1.y cd9b81672742 e2b1b6e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/19 06:10 linux-6.1.y cd9b81672742 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/19 06:10 linux-6.1.y cd9b81672742 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/17 13:04 linux-6.1.y bec0e10ee67e 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/14 17:06 linux-6.1.y bec0e10ee67e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/10 13:24 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/06 08:21 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/05 12:26 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/04 17:55 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/03 14:41 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/02 23:14 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2026/01/01 10:46 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/26 04:05 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/18 03:07 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/18 02:59 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/16 05:55 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/12 20:38 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
2025/12/09 12:13 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in unix_collect_skb
* Struck through repros no longer work on HEAD.