rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 1, t=10502 jiffies, g=71653, q=23) rcu: All QSes seen, last rcu_preempt kthread activity 10501 (4295017021-4295006520), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10502 jiffies! g71653 f0x2 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: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 22970 Comm: syz-executor.0 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:strlen+0x61/0x90 lib/string.c:569 Code: 00 00 fc ff df 48 89 e8 48 83 c0 01 48 89 c2 48 89 c1 48 c1 ea 03 83 e1 07 0f b6 14 1a 38 ca 7f 04 84 d2 75 1f 80 38 00 75 de <48> 83 c4 08 48 29 e8 5b 5d c3 48 83 c4 08 31 c0 5b 5d c3 e8 07 84 RSP: 0018:ffffc90000007d00 EFLAGS: 00000046 RAX: ffffffff898dde92 RBX: dffffc0000000000 RCX: 0000000000000002 RDX: 0000000000000003 RSI: ffff8880b9c223d8 RDI: ffffffff898dde80 RBP: ffffffff898dde80 R08: 0000000000000000 R09: 0000000000000001 R10: fffffbfff1adc97a R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff8b87c520 R14: ffff8880b9c223d8 R15: ffffc90000007de0 FS: 00007f9f3c5e2700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2f827000 CR3: 000000008d773000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: strlen include/linux/fortify-string.h:60 [inline] trace_event_get_offsets_lock_acquire include/trace/events/lock.h:13 [inline] perf_trace_lock_acquire+0xbe/0x550 include/trace/events/lock.h:13 trace_lock_acquire include/trace/events/lock.h:13 [inline] lock_acquire+0x416/0x510 kernel/locking/lockdep.c:5596 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 hrtimer_interrupt+0x103/0x790 kernel/time/hrtimer.c:1792 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:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5593 Code: 96 a6 7e 83 f8 01 0f 85 b4 02 00 00 9c 58 f6 c4 02 0f 85 9f 02 00 00 48 83 7c 24 08 00 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24 RSP: 0018:ffffc90004747758 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: 1ffff920008e8eed RCX: ffffffff815b111f RDX: 1ffff110123abd73 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8fd059f7 R10: fffffbfff1fa0b3e R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff8ba9f000 R15: 0000000000000000 __fs_reclaim_acquire mm/page_alloc.c:4539 [inline] fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4553 might_alloc include/linux/sched/mm.h:198 [inline] slab_pre_alloc_hook mm/slab.h:492 [inline] slab_alloc mm/slab.c:3306 [inline] kmem_cache_alloc_trace+0x39/0x480 mm/slab.c:3573 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: 0033:0x7f9f3f06ca39 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:00007f9f3c5e2188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f9f3f16ff60 RCX: 00007f9f3f06ca39 RDX: 0000000000101000 RSI: 0000000020000000 RDI: ffffffffffffff9c RBP: 00007f9f3f0c6c5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff6a3de97f R14: 00007f9f3c5e2300 R15: 0000000000022000 ---------------- Code disassembly (best guess), 4 bytes skipped: 0: df 48 89 fisttps -0x77(%rax) 3: e8 48 83 c0 01 callq 0x1c08350 8: 48 89 c2 mov %rax,%rdx b: 48 89 c1 mov %rax,%rcx e: 48 c1 ea 03 shr $0x3,%rdx 12: 83 e1 07 and $0x7,%ecx 15: 0f b6 14 1a movzbl (%rdx,%rbx,1),%edx 19: 38 ca cmp %cl,%dl 1b: 7f 04 jg 0x21 1d: 84 d2 test %dl,%dl 1f: 75 1f jne 0x40 21: 80 38 00 cmpb $0x0,(%rax) 24: 75 de jne 0x4 * 26: 48 83 c4 08 add $0x8,%rsp <-- trapping instruction 2a: 48 29 e8 sub %rbp,%rax 2d: 5b pop %rbx 2e: 5d pop %rbp 2f: c3 retq 30: 48 83 c4 08 add $0x8,%rsp 34: 31 c0 xor %eax,%eax 36: 5b pop %rbx 37: 5d pop %rbp 38: c3 retq 39: e8 .byte 0xe8 3a: 07 (bad) 3b: 84 .byte 0x84