rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: (detected by 0, t=10502 jiffies, g=139825, q=75) rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4295041734-4295031231), jiffies_till_next_fqs=1, root ->qsmask 0x0 rcu: rcu_preempt kthread starved for 10504 jiffies! g139825 f0x2 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:26544 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4940 [inline] __schedule+0xb72/0x1460 kernel/sched/core.c:6287 schedule+0x14b/0x210 kernel/sched/core.c:6366 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x1fd/0x770 kernel/rcu/tree.c:1957 rcu_gp_kthread+0xa5/0x350 kernel/rcu/tree.c:2130 kthread+0x453/0x480 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 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: 8015 Comm: syz-executor.3 Not tainted 5.15.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:check_wait_context kernel/locking/lockdep.c:4688 [inline] RIP: 0010:__lock_acquire+0x58b/0x2b00 kernel/locking/lockdep.c:4965 Code: c1 e0 06 48 8d 98 e0 1a 66 8f 48 ba 00 00 00 00 00 fc ff df 4c 8b 7c 24 28 48 81 c3 b8 00 00 00 48 89 d8 48 c1 e8 03 8a 04 10 <84> c0 0f 85 28 1a 00 00 44 8a 33 48 8b 44 24 38 8a 04 10 84 c0 0f RSP: 0000:ffffc90000dc0640 EFLAGS: 00000806 RAX: 1ffffffff1ecc700 RBX: ffffffff8f663998 RCX: ffffffff81651b2c RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffffffff8fd1aec0 RBP: ffffc90000dc0790 R08: dffffc0000000000 R09: fffffbfff1fa35d9 R10: fffffbfff1fa35d9 R11: 0000000000000000 R12: 0000000000000000 R13: ffff888049ddc340 R14: 0000000000000028 R15: ffff888049ddc318 FS: 00007f25969bc700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f259699afe8 CR3: 000000002f507000 CR4: 00000000003506e0 Call Trace: lock_acquire+0x19f/0x4d0 kernel/locking/lockdep.c:5625 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:267 rcu_read_lock include/linux/rcupdate.h:687 [inline] __perf_event_output kernel/events/core.c:7485 [inline] perf_event_output_forward+0xd9/0x2c0 kernel/events/core.c:7507 __perf_event_overflow+0x1f8/0x380 kernel/events/core.c:9177 perf_swevent_hrtimer+0x3d1/0x530 kernel/events/core.c:10567 __run_hrtimer kernel/time/hrtimer.c:1685 [inline] __hrtimer_run_queues+0x4cb/0xa60 kernel/time/hrtimer.c:1749 hrtimer_interrupt+0x3b3/0x1040 kernel/time/hrtimer.c:1811 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1086 [inline] __sysvec_apic_timer_interrupt+0xf9/0x270 arch/x86/kernel/apic/apic.c:1103 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1097 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0010:__schedule+0xb7a/0x1460 kernel/sched/core.c:6295 Code: 40 0a 00 00 fc 4c 89 fe 48 8d 94 24 a0 00 00 00 e8 cb e1 5f f7 48 8b 7c 24 08 4c 89 fe e8 ae 64 04 f7 48 89 c7 e8 a6 26 5e f7 <48> c7 44 24 60 0e 36 e0 45 48 b8 00 00 00 00 00 fc ff df 48 8b 4c RSP: 0000:ffffc900051ef4c0 EFLAGS: 00000282 RAX: be0751223b769500 RBX: ffff8880b9d31558 RCX: ffffffff90932903 RDX: dffffc0000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc900051ef5e0 R08: ffffffff818a0680 R09: ffffed10173a62a9 R10: ffffed10173a62a9 R11: 0000000000000000 R12: 1ffff110173a6400 R13: 0000000000000000 R14: ffff8880b9d32000 R15: dffffc0000000000 schedule+0x14b/0x210 kernel/sched/core.c:6366 tty_open+0x9b0/0xdd0 drivers/tty/tty_io.c:2153 chrdev_open+0x5fb/0x680 fs/char_dev.c:414 do_dentry_open+0x7cb/0x1020 fs/open.c:822 do_open fs/namei.c:3428 [inline] path_openat+0x28b4/0x3670 fs/namei.c:3561 do_filp_open+0x277/0x4f0 fs/namei.c:3588 do_sys_openat2+0x13b/0x500 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+0x243/0x290 fs/open.c:1227 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2599446a39 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:00007f25969bc188 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f2599549f60 RCX: 00007f2599446a39 RDX: 0000000000000802 RSI: 0000000020000840 RDI: ffffffffffffff9c RBP: 00007f25994a0c5f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffea77300cf R14: 00007f25969bc300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: c1 e0 06 shl $0x6,%eax 3: 48 8d 98 e0 1a 66 8f lea -0x7099e520(%rax),%rbx a: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx 11: fc ff df 14: 4c 8b 7c 24 28 mov 0x28(%rsp),%r15 19: 48 81 c3 b8 00 00 00 add $0xb8,%rbx 20: 48 89 d8 mov %rbx,%rax 23: 48 c1 e8 03 shr $0x3,%rax 27: 8a 04 10 mov (%rax,%rdx,1),%al * 2a: 84 c0 test %al,%al <-- trapping instruction 2c: 0f 85 28 1a 00 00 jne 0x1a5a 32: 44 8a 33 mov (%rbx),%r14b 35: 48 8b 44 24 38 mov 0x38(%rsp),%rax 3a: 8a 04 10 mov (%rax,%rdx,1),%al 3d: 84 c0 test %al,%al 3f: 0f .byte 0xf