rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=718c/1/0x4000000000000000 softirq=63773/63780 fqs=464 rcu: (detected by 1, t=10502 jiffies, g=53345, q=5986 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 14712 Comm: syz.8.1994 Not tainted 6.12.0-rc7-syzkaller-00125-gcfaaa7d010d1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 RIP: 0010:__raw_callee_save___pv_queued_spin_unlock+0x10/0x18 Code: 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 52 b8 01 00 00 00 31 d2 f0 0f b0 17 <75> 06 5a c3 cc cc cc cc 56 0f b6 f0 e8 9f ff ff ff 5e 5a c3 cc cc RSP: 0018:ffffc90000007b30 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 1ffffffff34b4785 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff9a5a3c20 RBP: dffffc0000000000 R08: ffffffff9a5a3c23 R09: 1ffffffff34b4784 R10: dffffc0000000000 R11: fffffbfff34b4785 R12: 1ffffffff34b4786 R13: ffffffff9a5a3c30 R14: ffffffff9a5a3c28 R15: ffffffff9a5a3c20 FS: 00007f2ad62d56c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020003c80 CR3: 00000000643d0000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: pv_queued_spin_unlock arch/x86/include/asm/paravirt.h:589 [inline] queued_spin_unlock arch/x86/include/asm/qspinlock.h:57 [inline] do_raw_spin_unlock+0x13c/0x8b0 kernel/locking/spinlock_debug.c:142 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock_irqrestore+0x81/0x140 kernel/locking/spinlock.c:194 debug_object_deactivate+0x2d5/0x390 lib/debugobjects.c:778 debug_hrtimer_deactivate kernel/time/hrtimer.c:428 [inline] debug_deactivate+0x1b/0x220 kernel/time/hrtimer.c:484 __run_hrtimer kernel/time/hrtimer.c:1659 [inline] __hrtimer_run_queues+0x305/0xd50 kernel/time/hrtimer.c:1755 hrtimer_interrupt+0x396/0x990 kernel/time/hrtimer.c:1817 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline] __sysvec_apic_timer_interrupt+0x110/0x420 arch/x86/kernel/apic/apic.c:1055 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:160 [inline] RIP: 0010:_raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:202 Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 3a 7c a7 f5 48 89 df e8 52 c2 a8 f5 e8 dd ae d3 f5 fb bf 01 00 00 00 d2 3d 9a f5 65 8b 05 b3 d5 3a 74 85 c0 74 06 5b c3 cc cc cc cc RSP: 0018:ffffc9000bb3fd00 EFLAGS: 00000286 RAX: 38075fa6b6cafe00 RBX: ffff888028e5d488 RCX: ffffffff9a39f903 RDX: dffffc0000000000 RSI: ffffffff8c0acac0 RDI: 0000000000000001 RBP: 00000000ffffff83 R08: ffffffff901bdfaf R09: 1ffffffff2037bf5 R10: dffffc0000000000 R11: fffffbfff2037bf6 R12: ffff888028e5d400 R13: 7fffffffffffffff R14: ffff888028e5d480 R15: 0000000000000003 spin_unlock_irq include/linux/spinlock.h:401 [inline] do_timerfd_settime+0xd33/0x1020 fs/timerfd.c:537 __do_sys_timerfd_settime fs/timerfd.c:583 [inline] __se_sys_timerfd_settime fs/timerfd.c:574 [inline] __x64_sys_timerfd_settime+0x16f/0x220 fs/timerfd.c:574 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2ad557e719 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f2ad62d5038 EFLAGS: 00000246 ORIG_RAX: 000000000000011e RAX: ffffffffffffffda RBX: 00007f2ad5735f80 RCX: 00007f2ad557e719 RDX: 0000000020000000 RSI: 0000000000000003 RDI: 000000000000000a RBP: 00007f2ad55f175e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2ad5735f80 R15: 00007ffc70959848 rcu: rcu_preempt kthread starved for 8090 jiffies! g53345 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:24112 pid:17 tgid:17 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5328 [inline] __schedule+0x17fa/0x4bd0 kernel/sched/core.c:6693 __schedule_loop kernel/sched/core.c:6770 [inline] schedule+0x14b/0x320 kernel/sched/core.c:6785 schedule_timeout+0x1be/0x310 kernel/time/timer.c:2615 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2045 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2247 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 1123 Comm: kworker/u8:7 Not tainted 6.12.0-rc7-syzkaller-00125-gcfaaa7d010d1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 Workqueue: writeback wb_workfn (flush-8:0) RIP: 0010:csd_lock_wait kernel/smp.c:340 [inline] RIP: 0010:smp_call_function_many_cond+0x19f3/0x2ca0 kernel/smp.c:884 Code: 45 8b 65 00 44 89 e6 83 e6 01 31 ff e8 86 f3 0b 00 41 83 e4 01 49 bc 00 00 00 00 00 fc ff df 75 07 e8 31 ef 0b 00 eb 38 f3 90 <42> 0f b6 04 23 84 c0 75 11 41 f7 45 00 01 00 00 00 74 1e e8 15 ef RSP: 0000:ffffc90003e45fa0 EFLAGS: 00000293 RAX: ffffffff8188fa9b RBX: 1ffff110170c8ca5 RCX: ffff88802745bc00 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90003e461a0 R08: ffffffff8188fa6a R09: 1ffff920007c8be4 R10: dffffc0000000000 R11: ffffffff81432160 R12: dffffc0000000000 R13: ffff8880b8646528 R14: ffff8880b873fc40 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f503a889d39 CR3: 000000000e734000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1051 __flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline] flush_tlb_multi arch/x86/mm/tlb.c:938 [inline] flush_tlb_mm_range+0x329/0x5c0 arch/x86/mm/tlb.c:1024 flush_tlb_page arch/x86/include/asm/tlbflush.h:254 [inline] ptep_clear_flush+0x11a/0x170 mm/pgtable-generic.c:101 page_vma_mkclean_one+0x58a/0x9a0 mm/rmap.c:1041 page_mkclean_one+0x280/0x420 mm/rmap.c:1082 rmap_walk_file+0x52f/0x9f0 mm/rmap.c:2697 rmap_walk mm/rmap.c:2715 [inline] folio_mkclean+0x262/0x440 mm/rmap.c:1114 folio_clear_dirty_for_io+0x22b/0xd00 mm/page-writeback.c:3024 mpage_submit_folio+0x88/0x230 fs/ext4/inode.c:1902 mpage_process_page_bufs+0x6c9/0x8d0 fs/ext4/inode.c:2034 mpage_prepare_extent_to_map+0xec7/0x1c80 fs/ext4/inode.c:2535 ext4_do_writepages+0xc55/0x3d20 fs/ext4/inode.c:2677 ext4_writepages+0x213/0x3c0 fs/ext4/inode.c:2813 do_writepages+0x35d/0x870 mm/page-writeback.c:2683 __writeback_single_inode+0x14f/0x10d0 fs/fs-writeback.c:1658 writeback_sb_inodes+0x80c/0x1370 fs/fs-writeback.c:1954 __writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2025 wb_writeback+0x42f/0xbd0 fs/fs-writeback.c:2136 wb_check_old_data_flush fs/fs-writeback.c:2240 [inline] wb_do_writeback fs/fs-writeback.c:2293 [inline] wb_workfn+0xba1/0x1090 fs/fs-writeback.c:2321 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244