============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- dhcpcd-run-hook/6093 is trying to acquire lock: ffff888041c73838 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 but task is already holding lock: ffff888031ecc038 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(rhashtable_bucket); lock(rhashtable_bucket); *** DEADLOCK *** May be due to missing lock nesting notation 5 locks held by dhcpcd-run-hook/6093: #0: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #0: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #0: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: __rhashtable_remove_fast include/linux/rhashtable.h:1137 [inline] #0: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] #0: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: pidfs_remove_pid+0x60/0x990 fs/pidfs.c:189 #1: ffff888031ecc038 (rhashtable_bucket){-.-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:331 #2: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #2: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #2: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: trace_call_bpf+0xb6/0xb80 kernel/trace/bpf_trace.c:-1 #3: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #3: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #3: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1183 [inline] #3: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rhtab_map_delete_elem+0x21/0x190 kernel/bpf/hashtab.c:2979 #4: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline] #4: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline] #4: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: __rhashtable_remove_fast include/linux/rhashtable.h:1137 [inline] #4: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] #4: ffffffff8eb59ce0 (rcu_read_lock){....}-{1:3}, at: rhtab_delete_elem+0x15c/0x1b30 kernel/bpf/hashtab.c:-1 stack backtrace: CPU: 1 UID: 0 PID: 6093 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x24df/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 rht_lock+0xa3/0x180 include/linux/rhashtable.h:331 __rhashtable_remove_fast_one include/linux/rhashtable.h:1065 [inline] __rhashtable_remove_fast include/linux/rhashtable.h:1146 [inline] rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] rhtab_delete_elem+0x404/0x1b30 kernel/bpf/hashtab.c:2954 rhtab_map_delete_elem+0xe2/0x190 kernel/bpf/hashtab.c:2985 bpf_prog_a4f1e23443ac9f8e+0x4e/0x56 bpf_dispatcher_nop_func include/linux/bpf.h:1450 [inline] __bpf_prog_run include/linux/filter.h:755 [inline] bpf_prog_run include/linux/filter.h:762 [inline] bpf_prog_run_array include/linux/bpf.h:2602 [inline] trace_call_bpf+0x3f0/0xb80 kernel/trace/bpf_trace.c:147 perf_trace_run_bpf_submit+0x78/0x170 kernel/events/core.c:11398 do_perf_trace_lock include/trace/events/lock.h:49 [inline] perf_trace_lock+0x32d/0x410 include/trace/events/lock.h:49 __do_trace_lock_release include/trace/events/lock.h:68 [inline] trace_lock_release include/trace/events/lock.h:68 [inline] lock_release+0x38e/0x3c0 kernel/locking/lockdep.c:5879 rht_assign_unlock include/linux/rhashtable.h:431 [inline] __rhashtable_remove_fast_one include/linux/rhashtable.h:1111 [inline] __rhashtable_remove_fast include/linux/rhashtable.h:1146 [inline] rhashtable_remove_fast include/linux/rhashtable.h:1175 [inline] pidfs_remove_pid+0x65b/0x990 fs/pidfs.c:189 free_pid+0x2c1/0x340 kernel/pid.c:143 free_pids+0xb6/0x100 kernel/pid.c:156 release_task+0x11e7/0x16c0 kernel/exit.c:300 wait_task_zombie kernel/exit.c:1314 [inline] wait_consider_task+0x197d/0x2df0 kernel/exit.c:1541 do_wait_thread kernel/exit.c:1604 [inline] __do_wait+0x148/0x720 kernel/exit.c:1722 do_wait+0x1e7/0x510 kernel/exit.c:1756 kernel_wait4+0x232/0x2b0 kernel/exit.c:1915 __do_sys_wait4 kernel/exit.c:1943 [inline] __se_sys_wait4 kernel/exit.c:1939 [inline] __x64_sys_wait4+0x166/0x240 kernel/exit.c:1939 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3aa3df8407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffcaa0b1580 EFLAGS: 00000202 ORIG_RAX: 000000000000003d RAX: ffffffffffffffda RBX: 00007f3aa3ca8c80 RCX: 00007f3aa3df8407 RDX: 0000000000000000 RSI: 00007ffcaa0b15ec RDI: ffffffffffffffff RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00005623ac4aa4c0 R13: 0000000000000001 R14: 00005623ac4a2910 R15: 00007f3aa4012460