rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (0 ticks this GP) idle=2174/1/0x4000000000000000 softirq=20854/20854 fqs=3 rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6629/1:b..l P6447/1:b..l rcu: (detected by 0, t=10506 jiffies, g=18385, q=431 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6625 Comm: syz.1.204 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:__sanitizer_cov_trace_pc+0x6b/0x70 kernel/kcov.c:231 Code: 82 18 17 00 00 83 f8 02 75 20 48 8b 8a 20 17 00 00 8b 92 1c 17 00 00 48 8b 01 48 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 RSP: 0018:ffffc90000a18e28 EFLAGS: 00000046 RAX: 8000000001000001 RBX: ffff8880b8328640 RCX: 0000000001000001 RDX: ffff88802f904b00 RSI: ffffffff81f77e2c RDI: ffff888038bf4300 RBP: 0000000000000000 R08: 0000000000000000 R09: fffff520001431b0 R10: ffffffff9cbab36b R11: 0000000000000000 R12: ffff888038bf4300 R13: 0000000000000000 R14: 0000000000000001 R15: ffff8880b8328690 FS: 00007f1a6b9a76c0(0000) GS:ffff888122a46000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b32afdff8 CR3: 000000005a3fa000 CR4: 00000000003526f0 Call Trace: trace_hrtimer_start+0x1c/0x220 include/trace/events/timer.h:223 debug_activate kernel/time/hrtimer.c:530 [inline] enqueue_hrtimer+0x84/0x2f0 kernel/time/hrtimer.c:1136 __run_hrtimer kernel/time/hrtimer.c:2090 [inline] __hrtimer_run_queues+0x6ed/0x9c0 kernel/time/hrtimer.c:2131 hrtimer_interrupt+0x441/0xaa0 kernel/time/hrtimer.c:2250 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:__sanitizer_cov_trace_pc+0x5b/0x70 kernel/kcov.c:218 Code: 00 00 f0 75 35 8b 82 44 17 00 00 85 c0 74 2b 8b 82 18 17 00 00 83 f8 02 75 20 48 8b 8a 20 17 00 00 8b 92 1c 17 00 00 48 8b 01 <48> 83 c0 01 48 39 d0 73 07 48 89 01 48 89 34 c1 c3 cc cc cc cc 90 RSP: 0018:ffffc9000e4cf840 EFLAGS: 00000246 RAX: 000000000007ffff RBX: 0000000000000000 RCX: ffffc9000ea99000 RDX: 0000000000080000 RSI: ffffffff81d23221 RDI: ffff88802f9051a8 RBP: ffff88805d83fb00 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc9000e4cf938 R11: 0000000000000000 R12: ffff888036630e10 R13: 0000000000000000 R14: 0000000000000000 R15: ffff88807b555a00 pid_nr_ns kernel/pid.c:547 [inline] pid_vnr+0x51/0x220 kernel/pid.c:558 scm_set_cred include/net/scm.h:73 [inline] unix_skb_to_scm net/unix/af_unix.c:2008 [inline] __unix_dgram_recvmsg+0x5d9/0xc30 net/unix/af_unix.c:2641 unix_dgram_recvmsg+0xcd/0x100 net/unix/af_unix.c:2689 sock_recvmsg_nosec net/socket.c:1151 [inline] ____sys_recvmsg+0x5eb/0x670 net/socket.c:2931 ___sys_recvmsg+0x16a/0x1a0 net/socket.c:2975 do_recvmmsg+0x2f3/0x740 net/socket.c:3070 __sys_recvmmsg net/socket.c:3144 [inline] __do_sys_recvmmsg net/socket.c:3167 [inline] __se_sys_recvmmsg net/socket.c:3160 [inline] __x64_sys_recvmmsg+0x22a/0x280 net/socket.c:3160 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f1a6ab9e1d9 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:00007f1a6b9a7028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007f1a6ae26090 RCX: 00007f1a6ab9e1d9 RDX: 0000000000010106 RSI: 00002000000002c0 RDI: 0000000000000004 RBP: 00007f1a6ac35888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f1a6ae26128 R14: 00007f1a6ae26090 R15: 00007ffcd6d9b7a8 task:syz.4.153 state:R running task stack:20232 pid:6447 tgid:6447 ppid:5602 task_flags:0x400640 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:7606 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+0x205/0xa10 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:37 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:179 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x70 kernel/kcov.c:213 Code: 48 89 df 5b e9 ed 10 68 00 be 03 00 00 00 5b e9 22 33 20 03 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <65> 48 8b 05 cc 59 81 13 48 8b 34 24 65 48 8b 15 b0 59 81 13 48 63 RSP: 0018:ffffc9000bad6a00 EFLAGS: 00000293 RAX: 0000000000000000 RBX: 0000000000000005 RCX: 0000000000000000 RDX: 0000000000000005 RSI: 0000000000000091 RDI: 0000000000000091 RBP: 0000000000000005 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000001 R13: 0000000000000091 R14: 0000000000000005 R15: 0000000000000091 avc_lookup+0x1a/0x240 security/selinux/avc.c:556 avc_has_perm_noaudit+0x97/0x470 security/selinux/avc.c:1159 cred_has_capability security/selinux/hooks.c:1675 [inline] selinux_vm_enough_memory+0x129/0x190 security/selinux/hooks.c:2278 security_vm_enough_memory_mm+0x96/0x110 security/security.c:748 shmem_acct_blocks mm/shmem.c:212 [inline] shmem_inode_acct_blocks+0x343/0x450 mm/shmem.c:228 shmem_alloc_and_add_folio+0x580/0xd40 mm/shmem.c:2008 shmem_get_folio_gfp+0x75b/0x1980 mm/shmem.c:2531 shmem_get_folio mm/shmem.c:2637 [inline] shmem_write_begin+0x1a4/0x420 mm/shmem.c:3268 generic_perform_write+0x292/0xa40 mm/filemap.c:4374 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3443 __kernel_write_iter+0x2ac/0x930 fs/read_write.c:621 dump_emit_page fs/coredump.c:1293 [inline] dump_user_range+0x3f9/0xad0 fs/coredump.c:1367 elf_core_dump+0x2d68/0x3d20 fs/binfmt_elf.c:2106 coredump_write fs/coredump.c:1047 [inline] do_coredump fs/coredump.c:1126 [inline] vfs_coredump+0x281a/0x54a0 fs/coredump.c:1195 get_signal+0x1f2a/0x21e0 kernel/signal.c:3097 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+0x402/0xa10 kernel/entry/common.c:165 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0033:0x7fb47859e1e1 RSP: 002b:fffffffffffffe70 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 00007fb478826090 RCX: 00007fb47859e1d9 RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000 RBP: 00007fb478635888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 00007fb478826128 R14: 00007fb478826090 R15: 00007fffad9b8088 task:syz.3.209 state:R running task stack:27112 pid:6629 tgid:6622 ppid:5605 task_flags:0x40044c flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 preempt_schedule_common+0x3c/0xb0 kernel/sched/core.c:7463 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12 __raw_spin_unlock include/linux/spinlock_api_smp.h:201 [inline] _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:213 spin_unlock include/linux/spinlock.h:401 [inline] zap_pte_range mm/memory.c:2095 [inline] zap_pmd_range mm/memory.c:2151 [inline] zap_pud_range mm/memory.c:2179 [inline] zap_p4d_range mm/memory.c:2200 [inline] __zap_vma_range+0x16b0/0x48e0 mm/memory.c:2240 unmap_vmas+0x299/0x5f0 mm/memory.c:2309 exit_mmap+0x1ef/0xa00 mm/mmap.c:1315 __mmput+0x12a/0x410 kernel/fork.c:1193 mmput+0x67/0x80 kernel/fork.c:1216 exit_mm kernel/exit.c:592 [inline] do_exit+0x83b/0x2a50 kernel/exit.c:974 do_group_exit+0xd5/0x2a0 kernel/exit.c:1129 get_signal+0x1ec7/0x21e0 kernel/signal.c:3112 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+0x139/0x700 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline] do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa64359e1d9 RSP: 002b:00007fa64442b0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007fa643826188 RCX: 00007fa64359e1d9 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fa643826188 RBP: 00007fa643826180 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa643826218 R14: 00007ffc28da9970 R15: 00007ffc28da9a58 rcu: rcu_preempt kthread starved for 10490 jiffies! g18385 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->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:R running task stack:27560 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7376 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x8f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x17a/0x220 kernel/rcu/tree.c:2330 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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: 0 UID: 0 PID: 6582 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 RIP: 0010:csd_lock_wait kernel/smp.c:363 [inline] RIP: 0010:csd_lock kernel/smp.c:396 [inline] RIP: 0010:smp_call_function_many_cond+0x577/0x18c0 kernel/smp.c:944 Code: e4 74 50 48 b8 00 00 00 00 00 fc ff df 48 89 ea 49 89 ec 48 c1 ea 03 41 83 e4 07 4c 8d 2c 02 41 83 c4 03 e8 0b c8 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 51 11 00 00 44 8b 73 08 RSP: 0000:ffffc9000764f7f8 EFLAGS: 00000293 RAX: 0000000000000000 RBX: ffff8880b8341900 RCX: 0000000000000002 RDX: ffff88807f06a580 RSI: ffffffff81ff7e45 RDI: ffff88807f06a580 RBP: ffff8880b8341908 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000003 R13: ffffed1017068321 R14: 0000000000000001 R15: 0000000000000001 FS: 00007f6fa8848880(0000) GS:ffff888122946000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000056252bde7fe8 CR3: 000000007509d000 CR4: 00000000003526f0 Call Trace: __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x3c9/0x1360 arch/x86/mm/tlb.c:1435 flush_tlb_page arch/x86/include/asm/tlbflush.h:352 [inline] ptep_clear_flush+0x148/0x170 mm/pgtable-generic.c:104 wp_page_copy mm/memory.c:4073 [inline] do_wp_page+0x1345/0x45c0 mm/memory.c:4472 handle_pte_fault mm/memory.c:6582 [inline] __handle_mm_fault+0x1cd2/0x2f60 mm/memory.c:6707 handle_mm_fault+0x363/0xa20 mm/memory.c:6876 do_user_addr_fault+0x59c/0x12f0 arch/x86/mm/fault.c:1343 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 RIP: 0033:0x7f6fa80b5db7 Code: 00 00 00 41 55 48 89 d0 49 89 fd 41 54 49 89 f4 53 4c 89 c3 48 83 ec 10 48 39 4f 60 0f 84 c1 00 00 00 42 f6 44 01 08 01 74 59 <48> 83 61 08 fe 48 3d ff 03 00 00 76 69 49 8b 55 70 49 8d 75 60 48 RSP: 002b:00007ffc5b352000 EFLAGS: 00010202 RAX: 0000000000006010 RBX: 00000000000001f0 RCX: 000056252bde7fe0 RDX: 0000000000006010 RSI: 000056252bde1fd0 RDI: 00007f6fa81f1ac0 RBP: 00007f6fa81f1ac0 R08: 00000000000001f0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 000056252bde1fd0 R13: 00007f6fa81f1ac0 R14: 00000000000001f0 R15: 00007f6fa81f1ac0