rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6468/1:b..l (detected by 1, t=10503 jiffies, g=19253, q=119) task:syz-executor.1 state:R running task stack:29600 pid: 6468 ppid: 3640 flags:0x00000000 Call Trace: context_switch kernel/sched/core.c:4972 [inline] __schedule+0xa9a/0x4940 kernel/sched/core.c:6253 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:6419 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x36/0x40 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:389 [inline] filemap_map_pages+0x104b/0x1630 mm/filemap.c:3344 do_fault_around mm/memory.c:4143 [inline] do_read_fault mm/memory.c:4158 [inline] do_fault mm/memory.c:4293 [inline] handle_pte_fault mm/memory.c:4551 [inline] __handle_mm_fault+0x28c6/0x5120 mm/memory.c:4686 handle_mm_fault+0x1c8/0x790 mm/memory.c:4784 do_user_addr_fault+0x489/0x11c0 arch/x86/mm/fault.c:1397 handle_page_fault arch/x86/mm/fault.c:1485 [inline] exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1541 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:568 RIP: 0033:0x7f1b2c0af923 RSP: 002b:00007ffcd2dcb960 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f1b2d14f3c0 RDX: 0000000000000001 RSI: 00007f1b2c1e7ef0 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f1b2c1e7ef0 R10: 000055555603a400 R11: 0000000000000202 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffcd2dcba20 rcu: rcu_preempt kthread starved for 10496 jiffies! g19253 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:28944 pid: 14 ppid: 2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:4972 [inline] __schedule+0xa9a/0x4940 kernel/sched/core.c:6253 schedule+0xd2/0x260 kernel/sched/core.c:6326 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: NMI backtrace for cpu 1 CPU: 1 PID: 6467 Comm: syz-executor.3 Not tainted 5.16.0-rc6-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:111 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline] rcu_check_gp_kthread_starvation.cold+0x1fb/0x200 kernel/rcu/tree_stall.h:481 print_other_cpu_stall kernel/rcu/tree_stall.h:586 [inline] check_cpu_stall kernel/rcu/tree_stall.h:729 [inline] rcu_pending kernel/rcu/tree.c:3878 [inline] rcu_sched_clock_irq+0x2125/0x2200 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:lock_acquire+0x1ef/0x510 kernel/locking/lockdep.c:5605 Code: 8d 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:ffffc90004f26fd8 EFLAGS: 00000206 RAX: dffffc0000000000 RBX: 1ffff920009e4dfd RCX: ffffffff815b9a1f RDX: 1ffff11004bf5d9b RSI: 0000000000000001 RDI: 0000000000000000 RBP: 0000000000000001 R08: 0000000000000000 R09: ffffffff8ff7ba9f R10: fffffbfff1fef753 R11: 000000000000003f R12: 0000000000000000 R13: 0000000000000000 R14: ffff888029c49580 R15: 0000000000000000 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:349 [inline] __dquot_alloc_space+0x644/0xb60 fs/quota/dquot.c:1657 dquot_reserve_block include/linux/quotaops.h:354 [inline] ext4_da_reserve_space+0x123/0x550 fs/ext4/inode.c:1468 ext4_insert_delayed_block fs/ext4/inode.c:1658 [inline] ext4_da_map_blocks fs/ext4/inode.c:1763 [inline] ext4_da_get_block_prep+0xc18/0x11f0 fs/ext4/inode.c:1827 ext4_block_write_begin+0x539/0x1140 fs/ext4/inode.c:1078 ext4_da_write_begin+0x3eb/0xad0 fs/ext4/inode.c:2966 generic_perform_write+0x205/0x510 mm/filemap.c:3754 ext4_buffered_write_iter+0x1ac/0x3b0 fs/ext4/file.c:269 ext4_file_write_iter+0x423/0x14e0 fs/ext4/file.c:681 call_write_iter include/linux/fs.h:2162 [inline] do_iter_readv_writev+0x472/0x750 fs/read_write.c:725 do_iter_write+0x188/0x710 fs/read_write.c:851 vfs_iter_write+0x70/0xa0 fs/read_write.c:892 iter_file_splice_write+0x6fa/0xc10 fs/splice.c:689 do_splice_from fs/splice.c:767 [inline] direct_splice_actor+0x110/0x180 fs/splice.c:936 splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891 do_splice_direct+0x1b3/0x280 fs/splice.c:979 do_sendfile+0xaf2/0x1250 fs/read_write.c:1245 __do_sys_sendfile64 fs/read_write.c:1310 [inline] __se_sys_sendfile64 fs/read_write.c:1296 [inline] __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1296 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: 0033:0x7f5daf596e99 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:00007f5dadf0c168 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f5daf6a9f60 RCX: 00007f5daf596e99 RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000004 RBP: 00007f5daf5f0ff1 R08: 0000000000000000 R09: 0000000000000000 R10: 00008400fffffffb R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc409e75ff R14: 00007f5dadf0c300 R15: 0000000000022000 sched: RT throttling activated ---------------- Code disassembly (best guess): 0: 8d a6 7e 83 f8 01 lea 0x1f8837e(%rsi),%esp 6: 0f 85 b4 02 00 00 jne 0x2c0 c: 9c pushfq d: 58 pop %rax e: f6 c4 02 test $0x2,%ah 11: 0f 85 9f 02 00 00 jne 0x2b6 17: 48 83 7c 24 08 00 cmpq $0x0,0x8(%rsp) 1d: 74 01 je 0x20 1f: fb sti 20: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 27: fc ff df * 2a: 48 01 c3 add %rax,%rbx <-- trapping instruction 2d: 48 c7 03 00 00 00 00 movq $0x0,(%rbx) 34: 48 c7 43 08 00 00 00 movq $0x0,0x8(%rbx) 3b: 00 3c: 48 rex.W 3d: 8b .byte 0x8b 3e: 84 .byte 0x84 3f: 24 .byte 0x24