============================================ WARNING: possible recursive locking detected 6.0.0-rc3-syzkaller-00545-gc3f760ef1287 #0 Not tainted -------------------------------------------- udevd/16742 is trying to acquire lock: ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: ____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline] ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:374 but task is already holding lock: ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: ____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline] ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:374 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(trace_printk_lock); lock(trace_printk_lock); *** DEADLOCK *** May be due to missing lock nesting notation 5 locks held by udevd/16742: #0: ffff888028ce8668 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xdf/0x1280 fs/seq_file.c:182 #1: ffff88801d10e088 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x47/0x440 fs/kernfs/file.c:162 #2: ffffffff8bf89380 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x0/0x340 kernel/trace/./bpf_trace.h:11 #3: ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: ____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline] #3: ffffffff8c0113f8 (trace_printk_lock){-.-.}-{2:2}, at: bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:374 #4: ffffffff8bf89380 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x0/0x340 kernel/trace/./bpf_trace.h:11 stack backtrace: CPU: 1 PID: 16742 Comm: udevd Not tainted 6.0.0-rc3-syzkaller-00545-gc3f760ef1287 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2988 [inline] check_deadlock kernel/locking/lockdep.c:3031 [inline] validate_chain kernel/locking/lockdep.c:3816 [inline] __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 ____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline] bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:374 bpf_prog_0605f9f479290f07+0x2f/0x33 bpf_dispatcher_nop_func include/linux/bpf.h:903 [inline] __bpf_prog_run include/linux/filter.h:594 [inline] bpf_prog_run include/linux/filter.h:601 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2046 [inline] bpf_trace_run2+0x110/0x340 kernel/trace/bpf_trace.c:2083 __bpf_trace_contention_begin+0xb5/0xf0 include/trace/events/lock.h:95 trace_contention_begin.constprop.0+0xda/0x1b0 include/trace/events/lock.h:95 __pv_queued_spin_lock_slowpath+0x103/0xb50 kernel/locking/qspinlock.c:405 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [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+0x200/0x2a0 kernel/locking/spinlock_debug.c:115 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0x41/0x50 kernel/locking/spinlock.c:162 ____bpf_trace_printk kernel/trace/bpf_trace.c:388 [inline] bpf_trace_printk+0xcf/0x170 kernel/trace/bpf_trace.c:374 bpf_prog_0605f9f479290f07+0x2f/0x33 bpf_dispatcher_nop_func include/linux/bpf.h:903 [inline] __bpf_prog_run include/linux/filter.h:594 [inline] bpf_prog_run include/linux/filter.h:601 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2046 [inline] bpf_trace_run2+0x110/0x340 kernel/trace/bpf_trace.c:2083 __bpf_trace_contention_begin+0xb5/0xf0 include/trace/events/lock.h:95 trace_contention_begin+0xc0/0x150 include/trace/events/lock.h:95 __mutex_lock_common kernel/locking/mutex.c:605 [inline] __mutex_lock+0x13c/0x1350 kernel/locking/mutex.c:747 kernfs_seq_start+0x47/0x440 fs/kernfs/file.c:162 seq_read_iter+0x2c6/0x1280 fs/seq_file.c:225 kernfs_fop_read_iter+0x523/0x710 fs/kernfs/file.c:299 call_read_iter include/linux/fs.h:2181 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x67d/0x930 fs/read_write.c:470 ksys_read+0x127/0x250 fs/read_write.c:607 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f592cb258fe Code: c0 e9 e6 fe ff ff 50 48 8d 3d 0e c7 09 00 e8 c9 cf 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 RSP: 002b:00007ffd7bdc3ec8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 000055ba77fe00b0 RCX: 00007f592cb258fe RDX: 0000000000001000 RSI: 000055ba77fe08a0 RDI: 0000000000000009 RBP: 00007f592cbf2380 R08: 0000000000000009 R09: 00007f592cbf5a60 R10: 0000000000000020 R11: 0000000000000246 R12: 000055ba77fe00b0 R13: 0000000000000d68 R14: 00007f592cbf1780 R15: 0000000000000d68