GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4818/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=242553, q=253 ncpus=2)
task:syz-executor state:R running task stack:21672 pid:4818 tgid:4818 ppid:4796 task_flags:0x400140 flags:0x00080001
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
preempt_schedule_irq+0xb5/0x150 kernel/sched/core.c:7256
irqentry_exit+0x6f/0x90 kernel/entry/common.c:211
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:unwind_next_frame+0x4c7/0x2390 arch/x86/kernel/unwind_orc.c:512
Code: 89 f8 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 2a 19 00 00 41 c6 07 01 48 c7 c2 a0 72 68 8b 4c 8b 6c 24 50 48 8d 72 04 4c 8d 62 05 <48> 89 f0 48 c1 e8 03 48 89 44 24 40 0f b6 04 28 84 c0 48 89 54 24
RSP: 0018:ffffc9000b3d6e98 EFLAGS: 00000202
RAX: 0000000000000002 RBX: ffffffff8ffed340 RCX: ffffffff8ffed344
RDX: ffffffff90b071ae RSI: ffffffff90b071b2 RDI: ffffffff8bbf0880
RBP: dffffc0000000000 R08: 0000000000000001 R09: ffffffff81738c45
R10: dffffc0000000000 R11: ffffffff81ac2e10 R12: ffffffff90b071b3
R13: ffffc9000b3d6fb8 R14: ffffc9000b3d6f68 R15: ffffffff81738c45
arch_stack_walk+0x11c/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
unpoison_slab_object mm/kasan/common.c:342 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:368
kasan_slab_alloc include/linux/kasan.h:252 [inline]
slab_post_alloc_hook mm/slub.c:4978 [inline]
slab_alloc_node mm/slub.c:5288 [inline]
kmem_cache_alloc_lru_noprof+0x35d/0x6d0 mm/slub.c:5307
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode+0x22/0x170 fs/inode.c:1145
debugfs_get_inode fs/debugfs/inode.c:72 [inline]
__debugfs_create_file+0x14d/0x4f0 fs/debugfs/inode.c:442
debugfs_create_file_unsafe+0x3a/0x50 fs/debugfs/inode.c:518
nsim_create+0x23f/0x1050 drivers/net/netdevsim/netdev.c:1139
__nsim_dev_port_add+0x6b6/0xb10 drivers/net/netdevsim/dev.c:1438
nsim_dev_port_add_all+0x37/0xf0 drivers/net/netdevsim/dev.c:1494
nsim_drv_probe+0x88e/0xba0 drivers/net/netdevsim/dev.c:1653
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x26d/0x9e0 drivers/base/dd.c:659
__driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
__device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
bus_for_each_drv+0x251/0x2e0 drivers/base/bus.c:462
__device_attach+0x2b8/0x400 drivers/base/dd.c:1031
bus_probe_device+0x185/0x260 drivers/base/bus.c:537
device_add+0x7b6/0xb50 drivers/base/core.c:3689
nsim_bus_dev_new drivers/net/netdevsim/bus.c:463 [inline]
new_device_store+0x36c/0x6f0 drivers/net/netdevsim/bus.c:191
kernfs_fop_write_iter+0x3af/0x540 fs/kernfs/file.c:352
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5c9/0xb30 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/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe1c4f8e1ff
RSP: 002b:00007ffdccdef4b0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fe1c4f8e1ff
RDX: 0000000000000003 RSI: 00007ffdccdef500 RDI: 0000000000000005
RBP: 00007fe1c50152ef R08: 0000000000000000 R09: 00007ffdccdef307
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003
R13: 00007ffdccdef500 R14: 00007fe1c5d14620 R15: 0000000000000003
rcu: rcu_preempt kthread starved for 10498 jiffies! g242553 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:26592 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000
Call Trace:
context_switch kernel/sched/core.c:5325 [inline]
__schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
__schedule_loop kernel/sched/core.c:7011 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7026
schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99
rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083
rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 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: 4913 Comm: syz.0.7942 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xd38/0x12d0 kernel/smp.c:877
Code: 89 ee 83 e6 01 31 ff e8 e6 73 0b 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 91 6f 0b 00 eb 38 f3 90 42 0f b6 04 2b <84> c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 75 6f 0b 00 eb e4 44
RSP: 0018:ffffc900048ff6c0 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 1ffff11017127ffd RCX: ffff888061490000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900048ff840 R08: ffffffff8f7cef77 R09: 1ffffffff1ef9dee
R10: dffffc0000000000 R11: fffffbfff1ef9def R12: ffff8880b893ffe8
R13: dffffc0000000000 R14: ffff8880b883b240 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff888126139000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc0c98ffe00 CR3: 000000007c47a000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1043
__flush_tlb_multi arch/x86/include/asm/paravirt.h:91 [inline]
flush_tlb_multi arch/x86/mm/tlb.c:1381 [inline]
flush_tlb_mm_range+0x6b1/0x12d0 arch/x86/mm/tlb.c:1471
tlb_flush arch/x86/include/asm/tlb.h:23 [inline]
tlb_flush_mmu_tlbonly include/asm-generic/tlb.h:490 [inline]
tlb_flush_mmu+0x1a7/0x680 mm/mmu_gather.c:403
tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:497
exit_mmap+0x444/0xb40 mm/mmap.c:1293
__mmput+0x118/0x430 kernel/fork.c:1133
exit_mm+0x1da/0x2c0 kernel/exit.c:582
do_exit+0x648/0x2300 kernel/exit.c:954
do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
__do_sys_exit_group kernel/exit.c:1118 [inline]
__se_sys_exit_group kernel/exit.c:1116 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116
x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9539b8f749
Code: Unable to access opcode bytes at 0x7f9539b8f71f.
RSP: 002b:00007ffe8e56f008 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9539b8f749
RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007ffe8e56f06c R08: 000000118e56f0ff R09: 00000000000927c0
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000046
R13: 00000000000927c0 R14: 000000000028be77 R15: 00007ffe8e56f0c0