rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 ticks this GP) idle=a6bc/1/0x4000000000000000 softirq=118984/118984 fqs=0 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P21351/1:b..l P21491/1:b..l P21359/1:b..l rcu: (detected by 1, t=10502 jiffies, g=85753, q=212 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 21492 Comm: syz.2.3435 Not tainted 6.16.0-rc5-syzkaller-00025-gd006330be3f7 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 RIP: 0010:__sanitizer_cov_trace_pc+0x5d/0x70 kernel/kcov.c:235 Code: 18 16 00 00 83 fa 02 75 21 48 8b 91 20 16 00 00 48 8b 32 48 8d 7e 01 8b 89 1c 16 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 cc cc cc cc cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 RSP: 0018:ffffc90000007d38 EFLAGS: 00000006 RAX: ffffffff81ae6c2a RBX: ffff8880b8627c08 RCX: ffff8880669c3c00 RDX: 0000000000010000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90000007e90 R08: ffffffff8fa0c5f7 R09: 1ffffffff1f418be R10: dffffc0000000000 R11: fffffbfff1f418bf R12: ffff888032939340 R13: 0000000000000000 R14: ffffffff898783c0 R15: 0000000000000001 FS: 00007f2a08c656c0(0000) GS:ffff888125c4f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2c218ff8 CR3: 0000000052828000 CR4: 00000000003526f0 Call Trace: get_current arch/x86/include/asm/current.h:25 [inline] __run_hrtimer kernel/time/hrtimer.c:1759 [inline] __hrtimer_run_queues+0x4ea/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:get_current mm/page_alloc.c:4071 [inline] RIP: 0010:current_gfp_context include/linux/sched/mm.h:252 [inline] RIP: 0010:fs_reclaim_release+0x4/0xa0 mm/page_alloc.c:4072 Code: ff ff ff 89 fd 48 89 df e8 d9 49 0d 00 89 ef e9 32 ff ff ff 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <55> 53 65 48 8b 1c 25 08 10 9d 92 48 83 c3 2c 48 89 d8 48 c1 e8 03 RSP: 0018:ffffc9000af1f9f0 EFLAGS: 00000287 RAX: 0000000000000000 RBX: 0000000000002800 RCX: dffffc0000000000 RDX: 0000000000002800 RSI: 0000000000000000 RDI: 0000000000002800 RBP: 0000000000002800 R08: 00000000ffffffff R09: 000000009f0cc0e2 R10: 000000000000000c R11: ffffffff81acf220 R12: ffffc9000af1fc00 R13: ffffc9000af1fc30 R14: ffff88801a44bdc0 R15: dffffc0000000000 might_alloc include/linux/sched/mm.h:319 [inline] slab_pre_alloc_hook mm/slub.c:4099 [inline] slab_alloc_node mm/slub.c:4177 [inline] kmem_cache_alloc_lru_noprof+0x50/0x3d0 mm/slub.c:4216 xas_alloc lib/xarray.c:378 [inline] xas_create+0x116b/0x1b90 lib/xarray.c:685 xas_store+0x95/0x1880 lib/xarray.c:795 __xa_store+0xe9/0x210 lib/xarray.c:1703 xa_store+0x33/0x50 lib/xarray.c:1734 __io_uring_add_tctx_node+0x1b2/0x4e0 io_uring/tctx.c:132 io_uring_create+0x71a/0xb60 io_uring/io_uring.c:3777 io_uring_setup io_uring/io_uring.c:3831 [inline] __do_sys_io_uring_setup io_uring/io_uring.c:3865 [inline] __se_sys_io_uring_setup+0x264/0x270 io_uring/io_uring.c:3856 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2a07d8e929 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:00007f2a08c64fc8 EFLAGS: 00000202 ORIG_RAX: 00000000000001a9 RAX: ffffffffffffffda RBX: 00007f2a07fb5fa0 RCX: 00007f2a07d8e929 RDX: 00002000000000c0 RSI: 00002000000002c0 RDI: 00000000000000a0 RBP: 00002000000002c0 R08: 0000000000000000 R09: 00002000000000c0 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 0000200000000040 R14: 00000000000000a0 R15: 00002000000000c0 task:udevd state:R running task stack:26352 pid:21359 tgid:21359 ppid:5206 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7113 irqentry_exit+0x6f/0x90 kernel/entry/common.c:307 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:rcu_read_unlock include/linux/rcupdate.h:869 [inline] RIP: 0010:mntput_no_expire+0x1b3/0x860 fs/namespace.c:1455 Code: 48 83 c3 58 48 89 d8 48 c1 e8 03 49 bc 00 00 00 00 00 fc ff df 42 80 3c 20 00 74 08 48 89 df e8 23 62 e6 ff 48 8b 03 65 ff 08 08 e5 2c 09 89 c3 31 ff 89 c6 e8 5d 0e 85 ff 85 db 74 10 e8 d4 RSP: 0018:ffffc90003327b40 EFLAGS: 00000286 RAX: 0000607ed9fd1418 RBX: ffff888033806598 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: ffffffff8be1ca20 RDI: ffffffff8be1c9e0 RBP: ffffc90003327c10 R08: 0000000000000000 R09: ffffffff823b19b9 R10: dffffc0000000000 R11: ffffed100f9f367b R12: dffffc0000000000 R13: 1ffff92000664f70 R14: ffffc90003327ba0 R15: ffffffff823b19b9 vfs_statx+0x36e/0x550 fs/stat.c:357 vfs_fstatat+0x118/0x170 fs/stat.c:375 __do_sys_newfstatat fs/stat.c:542 [inline] __se_sys_newfstatat fs/stat.c:536 [inline] __x64_sys_newfstatat+0x116/0x190 fs/stat.c:536 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2d06111b0a RSP: 002b:00007ffed81c8de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000106 RAX: ffffffffffffffda RBX: 000000000000000e RCX: 00007f2d06111b0a RDX: 00007ffed81c8df0 RSI: 00007ffed81c8ec0 RDI: 00000000ffffff9c RBP: 00007ffed81c9f00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffed81ca320 R13: 0000000000000000 R14: 0000563c921eb100 R15: 0000563c921eb140 task:syz.1.3436 state:R running task stack:26952 pid:21491 tgid:21490 ppid:20464 task_flags:0x400040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6970 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6994 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline] _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:186 spin_unlock include/linux/spinlock.h:391 [inline] copy_pte_range mm/memory.c:1206 [inline] copy_pmd_range+0x6727/0x7000 mm/memory.c:1267 copy_pud_range mm/memory.c:1304 [inline] copy_p4d_range mm/memory.c:1328 [inline] copy_page_range+0xc46/0x1270 mm/memory.c:1416 dup_mmap+0xf57/0x1ac0 mm/mmap.c:1838 dup_mm kernel/fork.c:1477 [inline] copy_mm+0x13c/0x4b0 kernel/fork.c:1529 copy_process+0x16d3/0x3b80 kernel/fork.c:2169 kernel_clone+0x224/0x7f0 kernel/fork.c:2599 __do_sys_clone kernel/fork.c:2742 [inline] __se_sys_clone kernel/fork.c:2726 [inline] __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2726 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb84d58e929 RSP: 002b:00007fb84e4c3fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007fb84d7b5fa0 RCX: 00007fb84d58e929 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000011 RBP: 00007fb84d610b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000001 R14: 00007fb84d7b5fa0 R15: 00007fffc670b8e8 task:udevd state:R running task stack:25984 pid:21351 tgid:21351 ppid:5206 task_flags:0x400140 flags:0x00004002 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6970 preempt_schedule+0xae/0xc0 kernel/sched/core.c:6994 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline] _raw_spin_unlock_irqrestore+0xfd/0x110 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline] __wake_up_common_lock+0x190/0x1f0 kernel/sched/wait.c:108 sock_def_readable+0x1fb/0x550 net/core/sock.c:3583 unix_dgram_sendmsg+0xd94/0x1870 net/unix/af_unix.c:2236 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x219/0x270 net/socket.c:727 sock_write_iter+0x258/0x330 net/socket.c:1131 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x548/0xa90 fs/read_write.c:686 ksys_write+0x145/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2d060a7407 RSP: 002b:00007ffed81ca770 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f2d06832880 RCX: 00007f2d060a7407 RDX: 0000000000000000 RSI: 00007ffed81ca817 RDI: 000000000000000a RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007f2d068326e8 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g85753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=0 timer-softirq=151204 rcu: rcu_preempt kthread starved for 10502 jiffies! g85753 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27000 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5401 [inline] __schedule+0x16a2/0x4cb0 kernel/sched/core.c:6790 __schedule_loop kernel/sched/core.c:6868 [inline] schedule+0x165/0x360 kernel/sched/core.c:6883 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2054 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2256 kthread+0x711/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 vkms_vblank_simulate: vblank timer overrun