rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5869/1:b..l P3092/1:b..l (detected by 0, t=10502 jiffies, g=18177, q=20 ncpus=2) task:udevd state:R running task stack:24600 pid:3092 ppid:1 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5241 [inline] __schedule+0x143f/0x4570 kernel/sched/core.c:6558 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6870 irqentry_exit+0x53/0x80 kernel/entry/common.c:439 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:653 RIP: 0010:__legitimize_mnt+0x0/0x190 fs/namespace.c:624 Code: 8b 34 24 48 c7 c7 48 47 01 8d e8 eb 06 71 ff ff 05 85 b5 07 0b 48 c7 c7 78 47 01 8d e9 49 3a b6 08 66 0f 1f 84 00 00 00 00 00 <55> 41 57 41 56 41 55 41 54 53 89 f5 49 89 ff e8 dc 11 91 ff 8b 1d RSP: 0018:ffffc9000318fb00 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 1ffff92000631f84 RCX: 1ffff92000631f8d RDX: 0000000000000000 RSI: 0000000000001e62 RDI: ffff88813fe4fca0 RBP: 0000000000001e62 R08: ffffffff81f544d6 R09: fffff52000631f86 R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff92000631f85 R13: ffffc9000318fc20 R14: ffffc9000318fc28 R15: dffffc0000000000 __legitimize_path fs/namei.c:701 [inline] legitimize_path fs/namei.c:718 [inline] try_to_unlazy+0xf3/0x5b0 fs/namei.c:779 complete_walk+0x118/0x360 fs/namei.c:888 path_parentat fs/namei.c:2528 [inline] __filename_parentat+0x27e/0x6e0 fs/namei.c:2550 filename_parentat fs/namei.c:2568 [inline] do_unlinkat+0x185/0x820 fs/namei.c:4363 __do_sys_unlink fs/namei.c:4440 [inline] __se_sys_unlink fs/namei.c:4438 [inline] __x64_sys_unlink+0x45/0x50 fs/namei.c:4438 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f0369917da7 RSP: 002b:00007ffda0668408 EFLAGS: 00000202 ORIG_RAX: 0000000000000057 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0369917da7 RDX: 0000000000000001 RSI: 00007ffda06684e0 RDI: 000055c26374f0d8 RBP: 0000000000000000 R08: 000000000f88bea9 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000bb8 R13: 0000000200000001 R14: 0000000000000001 R15: 0000000000000000 task:syz.3.490 state:R running task stack:24376 pid:5869 ppid:3645 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5241 [inline] __schedule+0x143f/0x4570 kernel/sched/core.c:6558 preempt_schedule_notrace+0xf8/0x140 kernel/sched/core.c:6820 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 rcu_is_watching+0x76/0xb0 kernel/rcu/tree.c:722 trace_lock_acquire include/trace/events/lock.h:24 [inline] lock_acquire+0xfa/0x5a0 kernel/locking/lockdep.c:5633 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] dput+0x54/0x1d0 fs/dcache.c:904 __fput+0x62e/0x8d0 fs/file_table.c:328 task_work_run+0x246/0x300 kernel/task_work.c:203 get_signal+0x15fc/0x17d0 kernel/signal.c:2647 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline] syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fb71eb79ef9 RSP: 002b:00007ffc7b6e6808 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007fb71ed17a80 RCX: 00007fb71eb79ef9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fb71ed17a80 R08: 0000000000000006 R09: 00007ffc7b6e6aff R10: 00000000003ff7d4 R11: 0000000000000246 R12: 000000000003e9a4 R13: 00007ffc7b6e6910 R14: 0000000000000032 R15: ffffffffffffffff rcu: rcu_preempt kthread starved for 10558 jiffies! g18177 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:26136 pid:16 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5241 [inline] __schedule+0x143f/0x4570 kernel/sched/core.c:6558 schedule+0xbf/0x180 kernel/sched/core.c:6634 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1965 rcu_gp_fqs_loop+0x2d2/0x1150 kernel/rcu/tree.c:1706 rcu_gp_kthread+0xa3/0x3b0 kernel/rcu/tree.c:1905 kthread+0x28d/0x320 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5873 Comm: syz.1.492 Not tainted 6.1.106-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 RIP: 0010:__lock_acquire+0x381/0x1f80 kernel/locking/lockdep.c:4986 Code: a2 77 00 48 8b 34 24 48 ba 00 00 00 00 00 fc ff df 4c 89 33 48 89 6c 24 20 48 8d 5c ee 18 48 89 d8 48 c1 e8 03 48 89 44 24 70 <80> 3c 10 00 4c 8b 6c 24 48 74 16 48 89 df e8 9c a2 77 00 48 8b 34 RSP: 0018:ffffc9000332f880 EFLAGS: 00000802 RAX: 1ffff1100f9098d9 RBX: ffff88807c84c6c8 RCX: ffff88807c84bb80 RDX: dffffc0000000000 RSI: ffff88807c84c660 RDI: ffffffff8d32afc0 RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000 R13: ffffffff81e170ee R14: ffffffff8d32afc0 R15: 000000000000002c FS: 00007ff4e23926c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe9fdd8f80 CR3: 000000005b162000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 rcu_lock_acquire include/linux/rcupdate.h:350 [inline] rcu_read_lock include/linux/rcupdate.h:791 [inline] percpu_ref_get_many include/linux/percpu-refcount.h:202 [inline] percpu_ref_get include/linux/percpu-refcount.h:222 [inline] obj_cgroup_get include/linux/memcontrol.h:784 [inline] memcg_slab_post_alloc_hook mm/slab.h:535 [inline] slab_post_alloc_hook+0x1bb/0x3a0 mm/slab.h:745 slab_alloc_node mm/slub.c:3398 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc+0x10c/0x2d0 mm/slub.c:3422 __sigqueue_alloc+0x42e/0x540 kernel/signal.c:435 __send_signal_locked+0x22f/0xdc0 kernel/signal.c:1128 do_send_sig_info kernel/signal.c:1300 [inline] group_send_sig_info+0x28a/0x300 kernel/signal.c:1448 bpf_send_signal_common+0x2d8/0x420 kernel/trace/bpf_trace.c:882 ____bpf_send_signal kernel/trace/bpf_trace.c:887 [inline] bpf_send_signal+0x15/0x20 kernel/trace/bpf_trace.c:885 bpf_prog_7ba5217f62dcd359+0x38/0x3c bpf_dispatcher_nop_func include/linux/bpf.h:989 [inline] __bpf_prog_run include/linux/filter.h:603 [inline] bpf_prog_run include/linux/filter.h:610 [inline] __bpf_trace_run kernel/trace/bpf_trace.c:2273 [inline] bpf_trace_run2+0x1fd/0x410 kernel/trace/bpf_trace.c:2312 __bpf_trace_sys_enter+0x60/0x70 include/trace/events/syscalls.h:18 trace_sys_enter include/trace/events/syscalls.h:18 [inline] syscall_trace_enter kernel/entry/common.c:81 [inline] __syscall_enter_from_user_work kernel/entry/common.c:100 [inline] syscall_enter_from_user_mode+0x206/0x230 kernel/entry/common.c:118 do_syscall_64+0x1e/0xb0 arch/x86/entry/common.c:77 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7ff4e1515849 Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25 RSP: 002b:00007ff4e2391a80 EFLAGS: 00000246 ORIG_RAX: 000000000000000f RAX: ffffffffffffffda RBX: 00007ff4e1715f80 RCX: 00007ff4e1515849 RDX: 00007ff4e2391a80 RSI: 00007ff4e2391bb0 RDI: 0000000000000011 RBP: 00007ff4e15e793e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ff4e1715f80 R15: 00007ffe9fdd91d8