rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: (detected by 1, t=10502 jiffies, g=4301, q=93) rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294978587-4294968085), jiffies_till_next_fqs=1, root ->qsmask 0x0 syz-executor438 R running task 26904 8296 8092 0x00000000 Call Trace: sched_show_task.cold+0x332/0x396 kernel/sched/core.c:5337 print_other_cpu_stall kernel/rcu/tree.c:1430 [inline] check_cpu_stall kernel/rcu/tree.c:1557 [inline] __rcu_pending kernel/rcu/tree.c:3293 [inline] rcu_pending kernel/rcu/tree.c:3336 [inline] rcu_check_callbacks.cold+0xb37/0xe19 kernel/rcu/tree.c:2682 update_process_times+0x2a/0x70 kernel/time/timer.c:1650 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:168 tick_sched_timer+0xfc/0x290 kernel/time/tick-sched.c:1278 __run_hrtimer kernel/time/hrtimer.c:1465 [inline] __hrtimer_run_queues+0x3f6/0xe60 kernel/time/hrtimer.c:1527 hrtimer_interrupt+0x326/0x9e0 kernel/time/hrtimer.c:1585 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1071 [inline] smp_apic_timer_interrupt+0x10c/0x550 arch/x86/kernel/apic/apic.c:1096 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:894 RIP: 0010:unwind_next_frame+0xe40/0x1400 arch/x86/kernel/unwind_orc.c:571 Code: 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 28 03 00 00 4d 89 66 40 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 0f b6 04 02 <84> c0 74 08 3c 03 0f 8e a0 03 00 00 41 39 2e 0f 85 8f 00 00 00 48 RSP: 0018:ffff888094be74b8 EFLAGS: 00000a06 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: 1ffff1101297cea0 RCX: 0000000000000000 RDX: 1ffff1101297cebd RSI: ffff888094be7448 RDI: ffff888094be7f38 RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000001 R10: ffff888094be7647 R11: 0000000000074071 R12: ffff888094be7f58 R13: ffff888094be761d R14: ffff888094be75e8 R15: ffffffff8b8cd904 __save_stack_trace+0x9f/0x190 arch/x86/kernel/stacktrace.c:44 save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:553 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc mm/slab.c:3397 [inline] kmem_cache_alloc_trace+0x11a/0x380 mm/slab.c:3623 kmalloc include/linux/slab.h:515 [inline] tty_alloc_file drivers/tty/tty_io.c:187 [inline] tty_open+0x138/0x990 drivers/tty/tty_io.c:2023 chrdev_open+0x266/0x770 fs/char_dev.c:423 do_dentry_open+0x4aa/0x1160 fs/open.c:796 do_last fs/namei.c:3421 [inline] path_openat+0x793/0x2df0 fs/namei.c:3537 do_filp_open+0x18c/0x3f0 fs/namei.c:3567 do_sys_open+0x3b3/0x520 fs/open.c:1085 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f0abc52faf9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0abc4e1318 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f0abc5b73e8 RCX: 00007f0abc52faf9 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f0abc5b73e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 7974742f7665642f R13: 00007fff488ba54f R14: 00007f0abc4e1400 R15: 0000000000022000 rcu: rcu_preempt kthread starved for 10502 jiffies! g4301 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: RCU grace-period kthread stack dump: rcu_preempt R running task 29760 10 2 0x80000000 Call Trace: context_switch kernel/sched/core.c:2828 [inline] __schedule+0x887/0x2040 kernel/sched/core.c:3517 schedule+0x8d/0x1b0 kernel/sched/core.c:3561 schedule_timeout+0x4cf/0xfe0 kernel/time/timer.c:1818 rcu_gp_kthread+0xdad/0x21c0 kernel/rcu/tree.c:2202 kthread+0x33f/0x460 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 ---------------- Code disassembly (best guess): 0: 48 89 fa mov %rdi,%rdx 3: 48 c1 ea 03 shr $0x3,%rdx 7: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) b: 0f 85 28 03 00 00 jne 0x339 11: 4d 89 66 40 mov %r12,0x40(%r14) 15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 1c: fc ff df 1f: 4c 89 f2 mov %r14,%rdx 22: 48 c1 ea 03 shr $0x3,%rdx 26: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax * 2a: 84 c0 test %al,%al <-- trapping instruction 2c: 74 08 je 0x36 2e: 3c 03 cmp $0x3,%al 30: 0f 8e a0 03 00 00 jle 0x3d6 36: 41 39 2e cmp %ebp,(%r14) 39: 0f 85 8f 00 00 00 jne 0xce 3f: 48 rex.W