rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=ce14/1/0x4000000000000000 softirq=125646/125647 fqs=5 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P19570/1:b..l rcu: (detected by 1, t=10502 jiffies, g=115337, q=592 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 19653 Comm: syz.7.3295 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026 RIP: 0010:debug_lockdep_rcu_enabled+0x2e/0x40 kernel/rcu/update.c:322 Code: 8b 05 6e 75 69 05 85 c0 74 20 8b 05 20 a8 69 05 85 c0 74 16 65 48 8b 05 c8 8d aa 08 8b 80 9c 0b 00 00 85 c0 0f 94 c0 0f b6 c0 fd 3e 03 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 90 90 90 RSP: 0018:ffffc90000007de0 EFLAGS: 00000046 RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffffffff898a2e26 RDX: ffff888032bc0000 RSI: ffffffff898a3144 RDI: ffff888032bc0000 RBP: ffff88802cd6b400 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 18c048a38cb8bce4 R14: ffff88802cd69c00 R15: ffff88802cd69c00 FS: 00007f005774e6c0(0000) GS:ffff888123dec000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2ddeaff8 CR3: 000000008c038000 CR4: 00000000003526f0 Call Trace: rcu_read_unlock include/linux/rcupdate.h:869 [inline] advance_sched+0x745/0xd20 net/sched/sch_taprio.c:994 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x462/0x9c0 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x109/0x470 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline] RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:198 Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 16 bf 29 f6 48 89 df e8 9e 0e 2a f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 01 00 00 00 e8 a5 1f 19 f6 65 8b 05 ee 98 a7 08 85 c0 74 16 5b RSP: 0018:ffffc9000445f6c8 EFLAGS: 00000246 RAX: 0000000000000006 RBX: ffffffff9b8b32a8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8e1a2a17 RDI: ffffffff8c400c80 RBP: 0000000000000282 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: 0000000000000200 R14: 0000000000000282 R15: 000000000000001e spin_unlock_irqrestore include/linux/spinlock.h:408 [inline] avc_reclaim_node security/selinux/avc.c:488 [inline] avc_alloc_node+0x3f5/0x670 security/selinux/avc.c:507 avc_insert security/selinux/avc.c:618 [inline] avc_compute_av+0x101/0x820 security/selinux/avc.c:993 avc_perm_nonode+0xb1/0x180 security/selinux/avc.c:1117 avc_has_perm_noaudit+0x2d4/0x3b0 security/selinux/avc.c:1160 selinux_inode_permission+0x8d4/0x1130 security/selinux/hooks.c:3280 security_inode_permission+0xda/0x250 security/security.c:1842 inode_permission+0x36c/0x620 fs/namei.c:661 may_open+0x2b8/0x480 fs/namei.c:4274 do_open fs/namei.c:4698 [inline] path_openat+0x8da/0x4280 fs/namei.c:4863 do_file_open+0x20e/0x430 fs/namei.c:4892 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f005679de59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f005774e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f0056a25fa0 RCX: 00007f005679de59 RDX: 0000000000040241 RSI: 0000200000000040 RDI: ffffffffffffff9c RBP: 00007f0056833e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f0056a26038 R14: 00007f0056a25fa0 R15: 00007ffc826a91b8 task:syz.6.3273 state:R running task stack:23032 pid:19570 tgid:19570 ppid:16684 task_flags:0x400640 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7556 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa00 kernel/entry/common.c:167 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:679 RIP: 0010:xas_invalid include/linux/xarray.h:1462 [inline] RIP: 0010:xas_valid include/linux/xarray.h:1473 [inline] RIP: 0010:xas_start+0x29/0x790 lib/xarray.c:186 Code: 90 41 56 41 55 41 54 55 53 48 89 fb 4c 8d 6b 18 e8 ac 2c 53 f6 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 <0f> 85 95 06 00 00 4c 8b 63 18 31 ff 4c 89 e5 83 e5 03 48 89 ee e8 RSP: 0018:ffffc900040deb88 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffc900040dec18 RCX: ffffffff8248d3ba RDX: 1ffff9200081bd86 RSI: ffffffff8bb6a394 RDI: ffffc900040dec18 RBP: 0000000000004d17 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffffc900040dec18 R13: ffffc900040dec30 R14: 0000000000000000 R15: 0000000000004d17 xas_load+0x1e/0x5c0 lib/xarray.c:239 filemap_get_entry+0x115/0x450 mm/filemap.c:1901 shmem_get_folio_gfp+0xa4e/0x1910 mm/shmem.c:2426 shmem_get_folio mm/shmem.c:2608 [inline] shmem_write_begin+0x1a4/0x420 mm/shmem.c:3239 generic_perform_write+0x292/0xa40 mm/filemap.c:4358 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3414 __kernel_write_iter+0x2ac/0x930 fs/read_write.c:621 dump_emit_page fs/coredump.c:1298 [inline] dump_user_range+0x3f9/0xad0 fs/coredump.c:1372 elf_core_dump+0x2d68/0x3d20 fs/binfmt_elf.c:2109 coredump_write fs/coredump.c:1052 [inline] do_coredump fs/coredump.c:1131 [inline] vfs_coredump+0x294b/0x56f0 fs/coredump.c:1200 get_signal+0x1f2a/0x21e0 kernel/signal.c:3023 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop kernel/entry/common.c:101 [inline] __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline] irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline] irqentry_exit+0x402/0xa00 kernel/entry/common.c:165 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0033:0x7f8eb8f9de61 RSP: 002b:fffffffffffffe70 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007f8eb9226090 RCX: 00007f8eb8f9de59 RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000 RBP: 00007f8eb9033e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007f8eb9226128 R14: 00007f8eb9226090 R15: 00007fff92e27378 rcu: rcu_preempt kthread starved for 10492 jiffies! g115337 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:26200 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5510 [inline] __schedule+0x125c/0x6730 kernel/sched/core.c:7234 __schedule_loop kernel/sched/core.c:7311 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7326 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2123 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2325 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: CPU: 1 UID: 0 PID: 29 Comm: kworker/1:1 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026 Workqueue: events fqdir_free_fn RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline] RIP: 0010:smp_call_function_single+0x204/0x710 kernel/smp.c:702 Code: bc 24 ce 00 00 00 48 89 84 24 d8 00 00 00 e8 a3 f9 ff ff 89 44 24 2c 0f 1f 44 00 00 e8 05 75 0c 00 eb 07 e8 fe 74 0c 00 f3 90 <8b> 9c 24 c8 00 00 00 31 ff 83 e3 01 89 de e8 59 6f 0c 00 85 db 75 RSP: 0018:ffffc90000a47a40 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fd5b57 RDX: ffff88801eed8000 RSI: ffffffff81fd5b42 RDI: ffff88801eed8000 RBP: ffffc90000a47b88 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001 R13: 0000000000000000 R14: ffff8880b843c540 R15: ffff8880b843c688 FS: 0000000000000000(0000) GS:ffff888123eec000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7328beb540 CR3: 000000008973c000 CR4: 00000000003526f0 Call Trace: rcu_barrier kernel/rcu/tree.c:3909 [inline] rcu_barrier+0x2a4/0x6d0 kernel/rcu/tree.c:3846 fqdir_free_fn+0x32/0x140 net/ipv4/inet_fragment.c:164 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245