syzbot


possible deadlock in __queue_map_get

Status: upstream: reported C repro on 2025/06/23 19:42
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+9a27d82855e38d482549@syzkaller.appspotmail.com
First crash: 5d21h, last: 1d16h
Bug presence (2)
Date Name Commit Repro Result
2025/06/28 linux-6.6.y (ToT) 3f5b4c104b7d C [report] possible deadlock in __queue_map_get
2025/06/28 upstream (ToT) 35e261cd95dd C Didn't crash
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 possible deadlock in __queue_map_get origin:upstream missing-backport C 27 4d11h 447d 0/3 upstream: reported C repro on 2024/04/08 00:56
upstream possible deadlock in __queue_map_get bpf C error 180 83d 442d 28/29 fixed on 2025/06/10 16:19

Sample crash report:
============================================
WARNING: possible recursive locking detected
6.6.94-syzkaller #0 Not tainted
--------------------------------------------
syz-executor343/5880 is trying to acquire lock:
ffff88807d2dd218 (&qs->lock){-.-.}-{2:2}, at: __queue_map_get+0x11c/0x4b0 kernel/bpf/queue_stack_maps.c:105

but task is already holding lock:
ffff888021f25218 (&qs->lock){-.-.}-{2:2}, at: __queue_map_get+0x11c/0x4b0 kernel/bpf/queue_stack_maps.c:105

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

       CPU0
       ----
  lock(&qs->lock);
  lock(&qs->lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

4 locks held by syz-executor343/5880:
 #0: ffff88802f0eb1f0 (&tsk->futex_exit_mutex){+.+.}-{3:3}, at: futex_cleanup_begin kernel/futex/core.c:1076 [inline]
 #0: ffff88802f0eb1f0 (&tsk->futex_exit_mutex){+.+.}-{3:3}, at: futex_exit_release+0x33/0x1d0 kernel/futex/core.c:1128
 #1: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #1: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #1: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline]
 #1: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361
 #2: ffff888021f25218 (&qs->lock){-.-.}-{2:2}, at: __queue_map_get+0x11c/0x4b0 kernel/bpf/queue_stack_maps.c:105
 #3: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #3: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #3: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline]
 #3: ffffffff8cd2f760 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361

stack backtrace:
CPU: 0 PID: 5880 Comm: syz-executor343 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain kernel/locking/lockdep.c:3856 [inline]
 __lock_acquire+0x5d40/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 __queue_map_get+0x11c/0x4b0 kernel/bpf/queue_stack_maps.c:105
 bpf_prog_00798911c748094f+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122
 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122
 trace_contention_end+0xe6/0x110 include/trace/events/lock.h:122
 __pv_queued_spin_lock_slowpath+0x7ec/0x9d0 kernel/locking/qspinlock.c:560
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
 _raw_spin_lock_irqsave+0xb4/0xf0 kernel/locking/spinlock.c:162
 __queue_map_get+0x11c/0x4b0 kernel/bpf/queue_stack_maps.c:105
 bpf_prog_00798911c748094f+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1213 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_contention_end+0xdd/0x130 include/trace/events/lock.h:122
 __traceiter_contention_end+0x78/0xb0 include/trace/events/lock.h:122
 trace_contention_end+0xc5/0xe0 include/trace/events/lock.h:122
 __mutex_lock_common kernel/locking/mutex.c:612 [inline]
 __mutex_lock+0x2fa/0xcc0 kernel/locking/mutex.c:747
 futex_cleanup_begin kernel/futex/core.c:1076 [inline]
 futex_exit_release+0x33/0x1d0 kernel/futex/core.c:1128
 exit_mm_release+0x1a/0x30 kernel/fork.c:1657
 exit_mm+0xa8/0x2c0 kernel/exit.c:541
 do_exit+0x886/0x23c0 kernel/exit.c:861
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1023
 __do_sys_exit_group kernel/exit.c:1034 [inline]
 __se_sys_exit_group kernel/exit.c:1032 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faba6172eb9
Code: 90 49 c7 c0 b8 ff ff ff be e7 00 00 00 ba 3c 00 00 00 eb 12 0f 1f 44 00 00 89 d0 0f 05 48 3d 00 f0 ff ff 77 1c f4 89 f0 0f 05 <48> 3d 00 f0 ff ff 76 e7 f7 d8 64 41 89 00 eb df 0f 1f 80 00 00 00
RSP: 002b:00007ffd2d5daf78 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007faba6172eb9
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007faba61ee2b0 R08: ffffffffffffffb8 R09: 00000000000000a0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007faba61ee2b0
R13: 0000000000000000 R14: 00007faba61eed20 R15: 00007faba6144070
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/23 19:42 linux-6.6.y 6282921b6825 d6cdfb8a .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf possible deadlock in __queue_map_get
* Struck through repros no longer work on HEAD.