rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10499 ticks this GP) idle=0f3/1/0x4000000000000000 softirq=56321/56321 fqs=0 (t=10500 jiffies g=96049 q=88) rcu: rcu_preempt kthread starved for 10500 jiffies! g96049 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:28696 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0x940/0x26f0 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: Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 29178 Comm: syz-executor.4 Not tainted 5.15.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_preemption_disabled+0x3e/0x170 lib/smp_processor_id.c:56 Code: 44 8b 25 5d 47 cc 76 65 8b 1d ee a1 cc 76 81 e3 ff ff ff 7f 31 ff 89 de 0f 1f 44 00 00 85 db 74 11 0f 1f 44 00 00 44 89 e0 5b <5d> 41 5c 41 5d 41 5e c3 0f 1f 44 00 00 9c 5b 81 e3 00 02 00 00 31 RSP: 0018:ffffc90014517708 EFLAGS: 00000002 RAX: 0000000000000001 RBX: ffff8880196e3900 RCX: 1ffffffff1adc5a9 RDX: 1ffff110032dc85a RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffffff89e42b20 R08: 0000000000000000 R09: 0000000000000001 R10: ffffffff817c2848 R11: 000000000000003f R12: 0000000000000001 R13: ffffffff898bfc80 R14: dead000000000100 R15: dffffc0000000000 FS: 00007f7a3b618700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd4adf74718 CR3: 0000000028f69000 CR4: 0000000000350ee0 Call Trace: lockdep_recursion_inc kernel/locking/lockdep.c:433 [inline] lockdep_hardirqs_on_prepare kernel/locking/lockdep.c:4279 [inline] lockdep_hardirqs_on_prepare+0x118/0x400 kernel/locking/lockdep.c:4232 trace_hardirqs_on+0x5b/0x1c0 kernel/trace/trace_preemptirq.c:49 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline] _raw_spin_unlock_irqrestore+0x50/0x70 kernel/locking/spinlock.c:194 __debug_check_no_obj_freed lib/debugobjects.c:1002 [inline] debug_check_no_obj_freed+0x20c/0x420 lib/debugobjects.c:1023 slab_free_hook mm/slub.c:1675 [inline] slab_free_freelist_hook+0xde/0x190 mm/slub.c:1725 slab_free mm/slub.c:3483 [inline] kfree+0xe4/0x530 mm/slub.c:4543 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: 0033:0x7f7a3e0a18d9 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:00007f7a3b618188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f7a3e1a5f60 RCX: 00007f7a3e0a18d9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f7a3e0fbcb4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd3b48ed0f R14: 00007f7a3b618300 R15: 0000000000022000 NMI backtrace for cpu 0 CPU: 0 PID: 29168 Comm: syz-executor.3 Not tainted 5.15.0-rc4-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_dump_cpu_stacks+0x25e/0x3f0 kernel/rcu/tree_stall.h:343 print_cpu_stall kernel/rcu/tree_stall.h:627 [inline] check_cpu_stall kernel/rcu/tree_stall.h:711 [inline] rcu_pending kernel/rcu/tree.c:3880 [inline] rcu_sched_clock_irq.cold+0x9d/0x746 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:__memset+0x2b/0x30 arch/x86/lib/memset_64.S:42 Code: 1f 44 00 00 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa <4c> 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3 aa 4c 89 c8 c3 90 49 RSP: 0018:ffffc90014367870 EFLAGS: 00000212 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88804253a6e0 RBP: ffff888010c41500 R08: 0000000000000000 R09: ffff88804253a6c0 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000cc0 R14: 0000000000000020 R15: 0000000000000cc0 slab_post_alloc_hook mm/slab.h:521 [inline] slab_alloc_node mm/slub.c:3206 [inline] slab_alloc mm/slub.c:3214 [inline] kmem_cache_alloc_trace+0x213/0x2b0 mm/slub.c:3231 kmalloc include/linux/slab.h:591 [inline] tty_alloc_file drivers/tty/tty_io.c:187 [inline] tty_open+0x140/0x1000 drivers/tty/tty_io.c:2140 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: 0033:0x7fdcd00948d9 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:00007fdccd60b188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fdcd0198f60 RCX: 00007fdcd00948d9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007fdcd00eecb4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffcdd8fdf7f R14: 00007fdccd60b300 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 44 8b 25 5d 47 cc 76 mov 0x76cc475d(%rip),%r12d # 0x76cc4764 7: 65 8b 1d ee a1 cc 76 mov %gs:0x76cca1ee(%rip),%ebx # 0x76cca1fc e: 81 e3 ff ff ff 7f and $0x7fffffff,%ebx 14: 31 ff xor %edi,%edi 16: 89 de mov %ebx,%esi 18: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 1d: 85 db test %ebx,%ebx 1f: 74 11 je 0x32 21: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 26: 44 89 e0 mov %r12d,%eax 29: 5b pop %rbx * 2a: 5d pop %rbp <-- trapping instruction 2b: 41 5c pop %r12 2d: 41 5d pop %r13 2f: 41 5e pop %r14 31: c3 retq 32: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 37: 9c pushfq 38: 5b pop %rbx 39: 81 e3 00 02 00 00 and $0x200,%ebx 3f: 31 .byte 0x31