============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.5.2251/16251 is trying to acquire lock: ffff88802643c038 (rhashtable_bucket){..-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:330 but task is already holding lock: ffff888075868038 (rhashtable_bucket){..-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:330 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 locks held by syz.5.2251/16251: 5, last CPU#1: #0: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: __rhashtable_remove_fast include/linux/rhashtable.h:1136 [inline] #0: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rhashtable_remove_fast include/linux/rhashtable.h:1174 [inline] #0: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: pidfs_remove_pid+0x60/0x990 fs/pidfs.c:189 #1: ffff888075868038 (rhashtable_bucket){..-.}-{0:0}, at: rht_lock+0x8b/0x180 include/linux/rhashtable.h:330 #2: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #2: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #2: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: trace_call_bpf+0xb4/0xb80 kernel/trace/bpf_trace.c:-1 #3: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #3: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #3: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline] #3: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rhtab_map_delete_elem+0x21/0x190 kernel/bpf/hashtab.c:3038 #4: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #4: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #4: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: __rhashtable_remove_fast include/linux/rhashtable.h:1136 [inline] #4: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rhashtable_remove_fast include/linux/rhashtable.h:1174 [inline] #4: ffffffff8fd5ca60 (rcu_read_lock){....}-{1:3}, at: rhtab_delete_elem+0x15f/0x1b00 kernel/bpf/hashtab.c:-1 stack backtrace: CPU: 1 UID: 0 PID: 16251 Comm: syz.5.2251 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_deadlock_bug+0x27a/0x290 kernel/locking/lockdep.c:3085 check_deadlock kernel/locking/lockdep.c:3137 [inline] validate_chain kernel/locking/lockdep.c:3939 [inline] __lock_acquire+0x25db/0x2de0 kernel/locking/lockdep.c:5288 lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942 rht_lock+0xa3/0x180 include/linux/rhashtable.h:330 __rhashtable_remove_fast_one include/linux/rhashtable.h:1064 [inline] __rhashtable_remove_fast include/linux/rhashtable.h:1145 [inline] rhashtable_remove_fast include/linux/rhashtable.h:1174 [inline] rhtab_delete_elem+0xb47/0x1b00 kernel/bpf/hashtab.c:3016 rhtab_map_delete_elem+0xe2/0x190 kernel/bpf/hashtab.c:3044 bpf_prog_a4f1e23443ac9f8e+0x4e/0x56 bpf_dispatcher_nop_func include/linux/bpf.h:1546 [inline] __bpf_prog_run include/linux/filter.h:784 [inline] bpf_prog_run include/linux/filter.h:791 [inline] bpf_prog_run_array include/linux/bpf.h:2759 [inline] trace_call_bpf+0x3f1/0xb80 kernel/trace/bpf_trace.c:147 perf_trace_run_bpf_submit+0x78/0x170 kernel/events/core.c:11440 do_perf_trace_lock include/trace/events/lock.h:49 [inline] perf_trace_lock+0x32e/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+0x396/0x3c0 kernel/locking/lockdep.c:5954 rht_assign_unlock include/linux/rhashtable.h:430 [inline] __rhashtable_remove_fast_one include/linux/rhashtable.h:1110 [inline] __rhashtable_remove_fast include/linux/rhashtable.h:1145 [inline] rhashtable_remove_fast include/linux/rhashtable.h:1174 [inline] pidfs_remove_pid+0x65b/0x990 fs/pidfs.c:189 free_pid+0x2c1/0x340 kernel/pid.c:143 release_task+0x124d/0x1740 kernel/exit.c:302 exit_notify kernel/exit.c:787 [inline] do_exit+0x168c/0x2360 kernel/exit.c:998 do_group_exit+0x22d/0x2f0 kernel/exit.c:1129 get_signal+0x121b/0x12c0 kernel/signal.c:3112 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1dcc99e2d9 Code: Unable to access opcode bytes at 0x7f1dcc99e2af. RSP: 002b:00007f1dcd8de0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f1dccc25fa8 RCX: 00007f1dcc99e2d9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f1dccc25fa8 RBP: 00007f1dccc25fa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1dccc26038 R14: 00007ffd3379d560 R15: 00007ffd3379d648