======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc3-syzkaller-g319fc77f8f45 #0 Not tainted
------------------------------------------------------
udevd/5209 is trying to acquire lock:
ffff88806e0ab410 (&htab->lockdep_key#110){....}-{2:2}, at: htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167

but task is already holding lock:
ffff888021b46020 (&htab->lockdep_key#109){....}-{2:2}, at: htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&htab->lockdep_key#109){....}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
       htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
       bpf_prog_6f5f05285f674219+0x43/0x4c
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
       __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
       __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
       trace_contention_begin+0x11b/0x140 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0x114/0xdb0 kernel/locking/qspinlock.c:402
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:577 [inline]
       queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x272/0x370 kernel/locking/spinlock_debug.c:116
       htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
       htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
       bpf_prog_6f5f05285f674219+0x43/0x4c
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
       __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
       __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
       trace_contention_begin+0xf9/0x120 include/trace/events/lock.h:95
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x1ad/0x1010 kernel/locking/mutex.c:730
       kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
       seq_read_iter+0x3cc/0xd70 fs/seq_file.c:225
       new_sync_read fs/read_write.c:484 [inline]
       vfs_read+0x975/0xb40 fs/read_write.c:565
       ksys_read+0x18f/0x2b0 fs/read_write.c:708
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&htab->lockdep_key#110){....}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
       htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
       bpf_prog_6f5f05285f674219+0x43/0x4c
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
       __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
       __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
       trace_contention_begin+0x11b/0x140 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0x114/0xdb0 kernel/locking/qspinlock.c:402
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:577 [inline]
       queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x272/0x370 kernel/locking/spinlock_debug.c:116
       htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
       htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
       bpf_prog_6f5f05285f674219+0x43/0x4c
       bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
       __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
       __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
       __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
       trace_contention_begin+0xf9/0x120 include/trace/events/lock.h:95
       __mutex_lock_common kernel/locking/mutex.c:587 [inline]
       __mutex_lock+0x1ad/0x1010 kernel/locking/mutex.c:730
       kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
       seq_read_iter+0x3cc/0xd70 fs/seq_file.c:225
       new_sync_read fs/read_write.c:484 [inline]
       vfs_read+0x975/0xb40 fs/read_write.c:565
       ksys_read+0x18f/0x2b0 fs/read_write.c:708
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&htab->lockdep_key#109);
                               lock(&htab->lockdep_key#110);
                               lock(&htab->lockdep_key#109);
  lock(&htab->lockdep_key#110);

 *** DEADLOCK ***

5 locks held by udevd/5209:
 #0: ffff8880655048b8 (&p->lock){+.+.}-{4:4}, at: seq_read_iter+0xb4/0xd70 fs/seq_file.c:182
 #1: ffff88807ed69c88 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
 #2: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #2: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2370 [inline]
 #2: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2412
 #3: ffff888021b46020 (&htab->lockdep_key#109){....}-{2:2}, at: htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
 #4: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #4: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #4: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2370 [inline]
 #4: ffffffff8eb38f60 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2412

stack backtrace:
CPU: 0 UID: 0 PID: 5209 Comm: udevd Not tainted 6.14.0-rc3-syzkaller-g319fc77f8f45 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
 htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
 bpf_prog_6f5f05285f674219+0x43/0x4c
 bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
 bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
 __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
 __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
 __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
 trace_contention_begin+0x11b/0x140 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0x114/0xdb0 kernel/locking/qspinlock.c:402
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:577 [inline]
 queued_spin_lock_slowpath+0x42/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x272/0x370 kernel/locking/spinlock_debug.c:116
 htab_lock_bucket+0x1a4/0x370 kernel/bpf/hashtab.c:167
 htab_lru_map_delete_elem+0x1f1/0x700 kernel/bpf/hashtab.c:1483
 bpf_prog_6f5f05285f674219+0x43/0x4c
 bpf_dispatcher_nop_func include/linux/bpf.h:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
 bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2412
 __bpf_trace_contention_begin+0x170/0x230 include/trace/events/lock.h:95
 __traceiter_contention_begin+0x7b/0xb0 include/trace/events/lock.h:95
 __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
 trace_contention_begin+0xf9/0x120 include/trace/events/lock.h:95
 __mutex_lock_common kernel/locking/mutex.c:587 [inline]
 __mutex_lock+0x1ad/0x1010 kernel/locking/mutex.c:730
 kernfs_seq_start+0x53/0x3b0 fs/kernfs/file.c:154
 seq_read_iter+0x3cc/0xd70 fs/seq_file.c:225
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0x975/0xb40 fs/read_write.c:565
 ksys_read+0x18f/0x2b0 fs/read_write.c:708
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7495f16b6a
Code: 00 3d 00 00 41 00 75 0d 50 48 8d 3d 2d 08 0a 00 e8 ea 7d 01 00 31 c0 e9 07 ff ff ff 64 8b 04 25 18 00 00 00 85 c0 75 1b 0f 05 <48> 3d 00 f0 ff ff 76 6c 48 8b 15 8f a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffdd3100b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000561d04861730 RCX: 00007f7495f16b6a
RDX: 0000000000001000 RSI: 0000561d0488c6b0 RDI: 000000000000000c
RBP: 0000561d04861730 R08: 000000000000000c R09: 0000000000000000
R10: 0000000000000010 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000003fff R14: 00007ffdd3101078 R15: 000000000000000a
 </TASK>