syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6581/1:b..l P5775/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=20337, q=694 ncpus=2)
task:udevd           state:R  running task     stack:24072 pid:5775  ppid:5138   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:get_current arch/x86/include/asm/current.h:41 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x60 kernel/kcov.c:215
Code: 00 00 f3 0f 1e fa 53 48 89 fb e8 13 00 00 00 48 8b 3d 1c 91 c4 0c 48 89 de 5b e9 13 9f 56 00 cc cc cc f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d b0 0a 7e 7e 65 8b 15 b1 0a 7e 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc9000476fa90 EFLAGS: 00000246
RAX: ffffffff81f0304c RBX: ffffc9000476fc40 RCX: 0000000000000000
RDX: ffff88807a590000 RSI: 0000000000000000 RDI: ffffc9000476fc40
RBP: 0000000000000000 R08: dffffc0000000000 R09: 1ffffffff21b2ca0
R10: dffffc0000000000 R11: fffffbfff21b2ca1 R12: dffffc0000000000
R13: 0000000000000040 R14: ffffc9000476fc40 R15: dffffc0000000000
 nd_jump_root+0x1c/0x410 fs/namei.c:960
 path_init+0x3e5/0x1200 fs/namei.c:2401
 path_lookupat+0x27/0x440 fs/namei.c:2481
 filename_lookup+0x1f4/0x510 fs/namei.c:2520
 user_path_at_empty+0x42/0x60 fs/namei.c:2917
 do_readlinkat+0xd8/0x480 fs/stat.c:494
 __do_sys_readlink fs/stat.c:527 [inline]
 __se_sys_readlink fs/stat.c:524 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:524
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fda255153a7
RSP: 002b:00007fff1ec3fd88 EFLAGS: 00000246 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 000055feb9222420 RCX: 00007fda255153a7
RDX: 0000000000000400 RSI: 00007fff1ec40240 RDI: 000055feb9222420
RBP: 000055feb9222457 R08: 0000000000000540 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000246 R12: 00007fff1ec40240
R13: 00007fff1ec3fe40 R14: 000055feaa5926d7 R15: 00007fff1ec40ed0
 </TASK>
task:syz-executor    state:R  running task     stack:21736 pid:6581  ppid:6571   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 unwind_next_frame+0x200f/0x2970 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf7/0x1f0 mm/page_owner.c:128
 __reset_page_owner+0x4e/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
 release_pages+0x1fa0/0x2220 mm/swap.c:1022
 __folio_batch_release+0x71/0xe0 mm/swap.c:1042
 folio_batch_release include/linux/pagevec.h:83 [inline]
 mapping_try_invalidate+0x438/0x4f0 mm/truncate.c:560
 btrfs_close_bdev fs/btrfs/volumes.c:1151 [inline]
 btrfs_close_one_device fs/btrfs/volumes.c:1175 [inline]
 close_fs_devices+0x42b/0x860 fs/btrfs/volumes.c:1217
 btrfs_close_devices+0xc6/0x500 fs/btrfs/volumes.c:1232
 close_ctree+0x80f/0xca0 fs/btrfs/disk-io.c:4484
 generic_shutdown_super+0x134/0x2b0 fs/super.c:693
 kill_anon_super+0x3b/0x70 fs/super.c:1303
 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2146
 deactivate_locked_super+0x97/0x100 fs/super.c:481
 cleanup_mnt+0x429/0x4c0 fs/namespace.c:1259
 task_work_run+0x1ce/0x250 kernel/task_work.c:245
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb96af90a77
RSP: 002b:00007ffc70bf8628 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007fb96b013d7d RCX: 00007fb96af90a77
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffc70bf86e0
RBP: 00007ffc70bf86e0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffc70bf9770
R13: 00007fb96b013d7d R14: 0000000000023fff R15: 00007ffc70bf97b0
 </TASK>
rcu: rcu_preempt kthread starved for 10578 jiffies! g20337 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:27752 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6909 Comm: syz.2.239 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:arch_stack_walk+0x14b/0x190 arch/x86/kernel/stacktrace.c:24
Code: ff 48 89 c6 e8 06 9d 53 00 4d 85 e4 74 2c 48 89 df 4c 89 e6 41 ff d6 84 c0 74 26 4c 89 ff e8 ec 90 08 00 83 bd 78 ff ff ff 00 <74> 1c e8 9e 98 53 00 eb c1 e8 97 98 53 00 eb 13 e8 90 98 53 00 eb
RSP: 0018:ffffc900001f06c8 EFLAGS: 00000002
RAX: ffffffff813ac001 RBX: ffffc900001f0780 RCX: ffff8880239d0000
RDX: 0000000000010000 RSI: 0000000080010003 RDI: 0000000000000000
RBP: ffffc900001f0750 R08: ffff8880239d0000 R09: 0000000000000003
R10: 0000000000000004 R11: 0000000000010000 R12: ffffffff81dc3d47
R13: 1ffff9200003e104 R14: ffffffff81748540 R15: ffffc900001f06c8
FS:  00007f804e4786c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c456682 CR3: 000000006a87d000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 save_stack+0xf7/0x1f0 mm/page_owner.c:128
 __set_page_owner+0x1d/0x60 mm/page_owner.c:192
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3503 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3510 [inline]
 kmem_cache_alloc+0x1b7/0x2e0 mm/slub.c:3519
 __sigqueue_alloc+0x40c/0x520 kernel/signal.c:438
 __send_signal_locked+0x22f/0xe00 kernel/signal.c:1130
 do_send_sig_info kernel/signal.c:1312 [inline]
 group_send_sig_info+0x1fa/0x260 kernel/signal.c:1462
 do_bpf_send_signal+0x7f/0x190 kernel/trace/bpf_trace.c:836
 irq_work_single+0xd5/0x230 kernel/irq_work.c:221
 irq_work_run_list kernel/irq_work.c:252 [inline]
 irq_work_run+0x156/0x2e0 kernel/irq_work.c:261
 __sysvec_irq_work+0x98/0x380 arch/x86/kernel/irq_work.c:22
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x9c/0xc0 arch/x86/kernel/irq_work.c:17
 </IRQ>
 <TASK>
 asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:723
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:207 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:147 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:254 [inline]
RIP: 0010:native_apic_msr_write+0x39/0x50 arch/x86/include/asm/apic.h:196
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 f3 0f 1e fa 89 f6 31 d2 e9 27 88 19 03 0f 1f 80 00 00 00
RSP: 0018:ffffc90003aa7cd8 EFLAGS: 00000246
RAX: 00000000000000f6 RBX: 0000000000000200 RCX: 000000000000083f
RDX: 0000000000000000 RSI: 00000000000000f6 RDI: 000000000000083f
RBP: 0000000000000000 R08: ffffc90003aa7c47 R09: 1ffff92000754f88
R10: dffffc0000000000 R11: fffff52000754f89 R12: ffff8880b8f35001
R13: dffffc0000000000 R14: ffff8880b8f35050 R15: 0000000000000020
 __apic_send_IPI_self arch/x86/include/asm/apic.h:454 [inline]
 arch_irq_work_raise+0x68/0x70 arch/x86/kernel/irq_work.c:31
 irq_work_queue+0x99/0x140 kernel/irq_work.c:124
 bpf_send_signal_common+0x2b6/0x420 kernel/trace/bpf_trace.c:875
 ____bpf_send_signal kernel/trace/bpf_trace.c:884 [inline]
 bpf_send_signal+0x19/0x20 kernel/trace/bpf_trace.c:882
 bpf_prog_7ba5217f62dcd359+0x40/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:616 [inline]
 bpf_prog_run include/linux/filter.h:623 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d1/0x3e0 kernel/trace/bpf_trace.c:2361
 trace_sys_enter+0x69/0x80 include/trace/events/syscalls.h:18
 syscall_trace_enter+0xf0/0x150 kernel/entry/common.c:81
 do_syscall_64+0x28/0xb0 arch/x86/entry/common.c:72
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f804d52b829
Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25
RSP: 002b:00007f804e477b40 EFLAGS: 00000246 ORIG_RAX: 000000000000000f
RAX: ffffffffffffffda RBX: 00007f804d7e6098 RCX: 00007f804d52b829
RDX: 00007f804e477b40 RSI: 00007f804e477c70 RDI: 0000000000000011
RBP: 00007f804d7e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f804d7e6128 R14: 00007ffe6e0d81f0 R15: 00007ffe6e0d82d8
 </TASK>
sched: RT throttling activated