rcu: INFO: rcu_preempt self-detected stall on CPU rcu: 0-...!: (10499 ticks this GP) idle=76d/1/0x4000000000000000 softirq=9206/9206 fqs=0 (t=10501 jiffies g=12161 q=535) rcu: rcu_preempt kthread starved for 10502 jiffies! g12161 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:4955 [inline] __schedule+0x940/0x26f0 kernel/sched/core.c:6236 schedule+0xd3/0x270 kernel/sched/core.c:6315 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881 rcu_gp_fqs_loop+0x186/0x810 kernel/rcu/tree.c:1955 rcu_gp_kthread+0x1de/0x320 kernel/rcu/tree.c:2128 kthread+0x405/0x4f0 kernel/kthread.c:327 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: 6548 Comm: syz-executor027 Not tainted 5.15.0-rc2-next-20210924-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:30 [inline] RIP: 0010:__orc_find+0x6a/0xf0 arch/x86/kernel/unwind_orc.c:52 Code: 89 de 49 39 ec 72 4d 4c 89 e0 48 29 e8 48 89 c2 48 c1 e8 3f 48 c1 fa 02 48 01 d0 48 d1 f8 48 8d 5c 85 00 48 89 d8 48 c1 e8 03 <42> 0f b6 14 38 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 48 RSP: 0018:ffffc900020bf510 EFLAGS: 00000a06 RAX: 1ffffffff1bc00c0 RBX: ffffffff8de00600 RCX: ffffffff89400067 RDX: 0000000000000007 RSI: ffffffff8e7ffc8a RDI: ffffffff8de005f4 RBP: ffffffff8de005f4 R08: 0000000000000000 R09: ffffffff8e7ffc8a R10: fffff52000417ed1 R11: 0000000000086089 R12: ffffffff8de00610 R13: ffffffff8de005f4 R14: ffffffff8de005f4 R15: dffffc0000000000 FS: 0000555556c6f300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fbfeb842140 CR3: 000000017b0ce000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: orc_find arch/x86/kernel/unwind_orc.c:173 [inline] unwind_next_frame+0x32a/0x1ce0 arch/x86/kernel/unwind_orc.c:443 arch_stack_walk+0x7d/0xe0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:121 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] ____kasan_kmalloc mm/kasan/common.c:513 [inline] ____kasan_kmalloc mm/kasan/common.c:472 [inline] __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:522 kmalloc include/linux/slab.h:592 [inline] io_add_buffers fs/io_uring.c:4423 [inline] io_provide_buffers fs/io_uring.c:4457 [inline] io_issue_sqe+0x1d9e/0x7430 fs/io_uring.c:6759 __io_queue_sqe+0x90/0xb50 fs/io_uring.c:6991 io_queue_sqe fs/io_uring.c:7042 [inline] io_submit_sqe fs/io_uring.c:7224 [inline] io_submit_sqes+0x21be/0x99d0 fs/io_uring.c:7329 __do_sys_io_uring_enter+0xf55/0x1f00 fs/io_uring.c:9995 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: 0033:0x7fbfeb7d0fb9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 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 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe945eef88 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 00000000000d7de4 RCX: 00007fbfeb7d0fb9 RDX: 0000000000000000 RSI: 00000000000069c1 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe945eefac R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000 INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.736 msecs NMI backtrace for cpu 0 CPU: 0 PID: 2575 Comm: kworker/u4:6 Not tainted 5.15.0-rc2-next-20210924-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_unbound io_ring_exit_work 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:3878 [inline] rcu_sched_clock_irq.cold+0x9d/0x746 kernel/rcu/tree.c:2597 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:1428 __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:unwind_next_frame+0xb7/0x1ce0 arch/x86/kernel/unwind_orc.c:621 Code: fc ff df 48 c7 04 13 00 00 00 00 48 8b 8c 24 98 00 00 00 65 48 2b 0c 25 28 00 00 00 0f 85 4c 15 00 00 48 81 c4 a0 00 00 00 5b <5d> 41 5c 41 5d 41 5e 41 5f c3 4d 8d 66 48 48 b8 00 00 00 00 00 fc RSP: 0018:ffffc9000b507710 EFLAGS: 00000282 RAX: 0000000000000001 RBX: ffffffff81648250 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: ffffc9000b507f28 RDI: 0000000000000001 RBP: ffffc9000b507f58 R08: ffffffff8dea4be6 R09: 0000000000000001 R10: fffff520016a0ef3 R11: 0000000000086089 R12: ffffc9000b500000 R13: ffffc9000b507775 R14: ffffc9000b507740 R15: ffffc9000b507774 arch_stack_walk+0x7d/0xe0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:121 kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xff/0x130 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1700 [inline] slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1726 slab_free mm/slub.c:3492 [inline] kfree+0xf6/0x560 mm/slub.c:4538 __io_remove_buffers fs/io_uring.c:4345 [inline] __io_remove_buffers fs/io_uring.c:4330 [inline] io_destroy_buffers fs/io_uring.c:9222 [inline] io_ring_ctx_free fs/io_uring.c:9279 [inline] io_ring_exit_work+0xbaa/0x1980 fs/io_uring.c:9460 process_one_work+0x9b2/0x1690 kernel/workqueue.c:2297 worker_thread+0x658/0x11f0 kernel/workqueue.c:2444 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 ---------------- Code disassembly (best guess): 0: 89 de mov %ebx,%esi 2: 49 39 ec cmp %rbp,%r12 5: 72 4d jb 0x54 7: 4c 89 e0 mov %r12,%rax a: 48 29 e8 sub %rbp,%rax d: 48 89 c2 mov %rax,%rdx 10: 48 c1 e8 3f shr $0x3f,%rax 14: 48 c1 fa 02 sar $0x2,%rdx 18: 48 01 d0 add %rdx,%rax 1b: 48 d1 f8 sar %rax 1e: 48 8d 5c 85 00 lea 0x0(%rbp,%rax,4),%rbx 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 0f b6 14 38 movzbl (%rax,%r15,1),%edx <-- trapping instruction 2f: 48 89 d8 mov %rbx,%rax 32: 83 e0 07 and $0x7,%eax 35: 83 c0 03 add $0x3,%eax 38: 38 d0 cmp %dl,%al 3a: 7c 04 jl 0x40 3c: 84 d2 test %dl,%dl 3e: 75 48 jne 0x88