rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P2970/1:b..l (detected by 0, t=10502 jiffies, g=47025, q=30) task:systemd-udevd state:R running task stack:22920 pid: 2970 ppid: 1 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:6687 irqentry_exit+0x31/0x80 kernel/entry/common.c:425 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:check_kcov_mode kernel/kcov.c:163 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x7/0x60 kernel/kcov.c:197 Code: fd ff ff b9 ff ff ff ff ba 08 00 00 00 4d 8b 03 48 0f bd ca 49 8b 45 00 48 63 c9 e9 64 ff ff ff 0f 1f 00 65 8b 05 59 e1 8b 7e <89> c1 48 8b 34 24 81 e1 00 01 00 00 65 48 8b 14 25 40 f0 01 00 a9 RSP: 0018:ffffc90001fb78b0 EFLAGS: 00000246 RAX: 0000000080000000 RBX: ffffffff8b83cce8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff888020ac2100 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff81725ef5 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: 00000000fffffffe R15: 0000000000000001 map_id_range_down_base kernel/user_namespace.c:289 [inline] map_id_range_down+0x181/0x340 kernel/user_namespace.c:302 map_id_down kernel/user_namespace.c:317 [inline] make_kuid+0x1e/0x30 kernel/user_namespace.c:394 kuid_into_mnt include/linux/fs.h:1640 [inline] i_uid_into_mnt include/linux/fs.h:1668 [inline] acl_permission_check fs/namei.c:341 [inline] generic_permission+0x88/0x5b0 fs/namei.c:403 do_inode_permission fs/namei.c:464 [inline] inode_permission.part.0+0x95/0x440 fs/namei.c:524 inode_permission fs/namei.c:505 [inline] may_lookup fs/namei.c:1683 [inline] link_path_walk.part.0+0x277/0xd00 fs/namei.c:2239 link_path_walk fs/namei.c:2221 [inline] path_lookupat+0xc8/0x860 fs/namei.c:2448 filename_lookup+0x1c6/0x590 fs/namei.c:2478 user_path_at_empty+0x42/0x60 fs/namei.c:2801 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x142/0x390 fs/stat.c:221 vfs_fstatat fs/stat.c:243 [inline] vfs_lstat include/linux/fs.h:3356 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:398 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+0x44/0xae RIP: 0033:0x7fe0e8faa335 RSP: 002b:00007fffd8204728 EFLAGS: 00000246 ORIG_RAX: 0000000000000006 RAX: ffffffffffffffda RBX: 000055ece6e8b380 RCX: 00007fe0e8faa335 RDX: 00007fffd8204760 RSI: 00007fffd8204760 RDI: 000055ece6e8a380 RBP: 00007fffd8204820 R08: 00007fe0e9269258 R09: 0000000000001010 R10: 0000000000000020 R11: 0000000000000246 R12: 000055ece6e8a380 R13: 000055ece6e8a3a6 R14: 000055ece6e62ae1 R15: 000055ece6e62ae6 rcu: rcu_preempt kthread starved for 10500 jiffies! g47025 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 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:28952 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb44/0x5960 kernel/sched/core.c:6287 schedule+0xd3/0x270 kernel/sched/core.c:6366 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x800 kernel/rcu/tree.c:1957 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2130 kthread+0x3e5/0x4d0 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 rcu: Stack dump where RCU GP kthread last ran: NMI backtrace for cpu 0 CPU: 0 PID: 15599 Comm: syz-executor.4 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace+0x1ae/0x220 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq+0x2125/0x2200 kernel/rcu/tree.c:2599 update_process_times+0x16d/0x200 kernel/time/timer.c:1785 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1421 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x31c/0x790 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0x146/0x530 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:638 RIP: 0010:kfree+0x137/0x2c0 mm/slab.c:3805 Code: 0e 4c 89 ea 48 89 ee 4c 89 e7 e8 d4 f8 ff ff 48 85 db 0f 85 a6 00 00 00 9c 58 f6 c4 02 0f 85 74 01 00 00 48 85 db 74 01 fb 5b <5d> 41 5c 41 5d c3 65 8b 05 24 2d 45 7e 83 f8 07 0f 87 61 01 00 00 RSP: 0000:ffffc90003e3f8a0 EFLAGS: 00000206 RAX: 0000000000000006 RBX: fffffffffffffff5 RCX: 1ffffffff1adc449 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff888084f195c0 R08: 0000000000000001 R09: 0000000000000001 R10: ffffffff817c38e8 R11: 0000000000086089 R12: ffff888010c40100 R13: ffffffff842f5a70 R14: dffffc0000000000 R15: ffff888068cefa80 tty_free_file drivers/tty/tty_io.c:220 [inline] tty_open+0x7e0/0x1000 drivers/tty/tty_io.c:2149 chrdev_open+0x266/0x770 fs/char_dev.c:414 do_dentry_open+0x4c8/0x11d0 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x1c9a/0x2740 fs/namei.c:3561 do_filp_open+0x1aa/0x400 fs/namei.c:3588 do_sys_openat2+0x16d/0x4d0 fs/open.c:1200 do_sys_open fs/open.c:1216 [inline] __do_sys_openat fs/open.c:1232 [inline] __se_sys_openat fs/open.c:1227 [inline] __x64_sys_openat+0x13f/0x1f0 fs/open.c:1227 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+0x44/0xae RIP: 0033:0x7f925bf92a39 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f9259508188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f925c095f60 RCX: 00007f925bf92a39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f925bfecc5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff15978b4f R14: 00007f9259508300 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess), 3 bytes skipped: 0: b9 ff ff ff ff mov $0xffffffff,%ecx 5: ba 08 00 00 00 mov $0x8,%edx a: 4d 8b 03 mov (%r11),%r8 d: 48 0f bd ca bsr %rdx,%rcx 11: 49 8b 45 00 mov 0x0(%r13),%rax 15: 48 63 c9 movslq %ecx,%rcx 18: e9 64 ff ff ff jmpq 0xffffff81 1d: 0f 1f 00 nopl (%rax) 20: 65 8b 05 59 e1 8b 7e mov %gs:0x7e8be159(%rip),%eax # 0x7e8be180 * 27: 89 c1 mov %eax,%ecx <-- trapping instruction 29: 48 8b 34 24 mov (%rsp),%rsi 2d: 81 e1 00 01 00 00 and $0x100,%ecx 33: 65 48 8b 14 25 40 f0 mov %gs:0x1f040,%rdx 3a: 01 00 3c: a9 .byte 0xa9