GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-...!: (1 GPs behind) idle=cb0c/1/0x4000000000000000 softirq=149502/149503 fqs=0
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P25413/1:b..l
rcu: (detected by 0, t=10505 jiffies, g=163581, q=455 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 18022 Comm: syz-executor Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:rb_red_parent lib/rbtree.c:66 [inline]
RIP: 0010:__rb_insert lib/rbtree.c:88 [inline]
RIP: 0010:rb_insert_color+0x2a/0x810 lib/rbtree.c:436
Code: f3 0f 1e fa 48 b8 00 00 00 00 00 fc ff df 41 57 48 89 fa 41 56 48 c1 ea 03 41 55 41 54 49 89 fc 55 53 48 83 ec 08 80 3c 02 00 <0f> 85 af 05 00 00 49 be 00 00 00 00 00 fc ff df 49 8b 1c 24 48 85
RSP: 0018:ffffc90000a08df0 EFLAGS: 00000046
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000003
RDX: 1ffff1100565e860 RSI: ffff8880b8528698 RDI: ffff88802b2f4300
RBP: ffff8880b8528698 R08: 0000000000000005 R09: 000000000000001f
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88802b2f4300
R13: ffff88802b2f4318 R14: ffff8880b8528648 R15: ffff8880b8528698
FS: 0000555584cd3500(0000) GS:ffff8881243e7000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbcf6b456b8 CR3: 00000000530db000 CR4: 00000000003526f0
Call Trace:
__rb_add include/linux/rbtree.h:239 [inline]
rb_add_linked include/linux/rbtree.h:281 [inline]
timerqueue_linked_add+0x236/0x430 lib/timerqueue.c:96
enqueue_hrtimer+0x1ad/0x2f0 kernel/time/hrtimer.c:1117
__run_hrtimer kernel/time/hrtimer.c:2048 [inline]
__hrtimer_run_queues+0x6ed/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:lock_acquire+0x5e/0x370 kernel/locking/lockdep.c:5872
Code: 05 3b 80 2e 12 83 f8 07 0f 87 da 00 00 00 48 0f a3 05 86 76 f6 0e 0f 82 ac 02 00 00 8b 35 4e aa f6 0e 85 f6 0f 85 c7 00 00 00 <48> 8b 44 24 30 65 48 2b 05 dd 7f 2e 12 0f 85 ec 02 00 00 48 83 c4
RSP: 0018:ffffc90002eb7358 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8df34f31 RDI: ffffffff8c1e7f80
RBP: ffffffff8e7e60c0 R08: 000000005b336a06 R09: 0000000000000007
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0xd1/0x2090 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
unpoison_slab_object mm/kasan/common.c:340 [inline]
__kasan_slab_alloc+0x89/0x90 mm/kasan/common.c:366
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x26b/0x6a0 mm/slub.c:4959
vm_area_dup+0x27/0x8e0 mm/vma_init.c:123
dup_mmap+0x6f6/0x21b0 mm/mmap.c:1786
dup_mm kernel/fork.c:1538 [inline]
copy_mm kernel/fork.c:1590 [inline]
copy_process+0x4588/0x8030 kernel/fork.c:2288
kernel_clone+0x176/0x9d0 kernel/fork.c:2747
__do_sys_clone+0xd9/0x120 kernel/fork.c:2888
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: 0033:0x7fbcf5dc58d2
Code: 89 e7 e8 71 8b f7 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 66 89 c5 85 c0 75 3b 64 48 8b 04 25 10 00 00
RSP: 002b:00007ffd1e09df20 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007ffd1e09df20 RCX: 00007fbcf5dc58d2
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007ffd1e09e0ac R08: 0000000000000000 R09: 0000000000000001
R10: 0000555584cd37d0 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000000927c0 R14: 000000000015fa63 R15: 00007ffd1e09e100
task:syz.0.4638 state:R running task stack:26776 pid:25413 tgid:25408 ppid:19897 task_flags:0x40044c flags:0x00080001
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_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:109 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:127 [inline]
RIP: 0010:lock_acquire kernel/locking/lockdep.c:5864 [inline]
RIP: 0010:lock_acquire+0x166/0x370 kernel/locking/lockdep.c:5825
Code: bd 00 00 00 65 8b 05 c9 c5 2e 12 85 c0 0f 85 ae 00 00 00 65 48 8b 05 01 7f 2e 12 8b 90 9c 0b 00 00 85 d2 0f 85 98 00 00 00 9c <8f> 04 24 fa 48 c7 c7 1d db 04 8e e8 3a ca b6 09 45 89 e8 44 89 e1
RSP: 0018:ffffc900041df0c0 EFLAGS: 00000246
RAX: ffff888027b1ca80 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff8284869d RDI: fffffbfff1cfcc18
RBP: ffffffff8e7e60c0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000070e02d4 R11: 000000000000c7a3 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
__update_page_owner_free_handle.isra.0+0x4d/0x4d0 mm/page_owner.c:283
__reset_page_owner+0x93/0x190 mm/page_owner.c:321
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
free_unref_folios+0xa44/0x1710 mm/page_alloc.c:3011
folios_put_refs+0x585/0xaa0 mm/swap.c:1057
folio_batch_release include/linux/folio_batch.h:101 [inline]
shmem_undo_range+0x5e5/0x1570 mm/shmem.c:1149
shmem_truncate_range mm/shmem.c:1277 [inline]
shmem_evict_inode+0x3a5/0xbe0 mm/shmem.c:1407
evict+0x3c2/0xad0 fs/inode.c:825
iput_final fs/inode.c:2019 [inline]
iput.part.0+0x989/0x1050 fs/inode.c:2068
iput+0x35/0x40 fs/inode.c:2034
dentry_unlink_inode+0x284/0x470 fs/dcache.c:479
dentry_kill+0x25d/0xc20 fs/dcache.c:826
finish_dput fs/dcache.c:1001 [inline]
dput.part.0+0xd7/0x240 fs/dcache.c:1042
dput+0x1f/0x30 fs/dcache.c:1037
__fput+0x519/0xb50 fs/file_table.c:520
task_work_run+0x150/0x240 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x951/0x2ae0 kernel/exit.c:1004
do_group_exit+0xd5/0x2a0 kernel/exit.c:1147
get_signal+0x1ec7/0x21e0 kernel/signal.c:3038
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+0x139/0x6f0 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:318 [inline]
do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe19ad9ce59
RSP: 002b:00007fe19bce8028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: 0000000000010106 RBX: 00007fe19b016180 RCX: 00007fe19ad9ce59
RDX: 0000000000010106 RSI: 00002000000000c0 RDI: 0000000000000009
RBP: 00007fe19ae32e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe19b016218 R14: 00007fe19b016180 R15: 00007ffe7b3be558
rcu: rcu_preempt kthread starved for 10505 jiffies! g163581 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:26856 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: 0 UID: 0 PID: 14177 Comm: kworker/u8:27 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: writeback wb_workfn (flush-8:0)
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x589/0x16c0 kernel/smp.c:892
Code: b8 00 00 00 00 00 fc ff df 48 8b 54 24 08 49 89 d5 49 89 d4 49 c1 ed 03 41 83 e4 07 49 01 c5 41 83 c4 03 e8 b9 95 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 2c 0f 00 00 8b 45 08 31
RSP: 0018:ffffc90003b26820 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81fcea0d
RDX: ffff8880562c8000 RSI: ffffffff81fce9e7 RDI: ffff8880562c8000
RBP: ffff8880b8541240 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10170a8249 R14: 0000000000000001 R15: ffff8880b843c880
FS: 0000000000000000(0000) GS:ffff8881242e7000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000035030 CR3: 000000007e5c5000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 00000000fda3b69a DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
on_each_cpu_cond_mask+0x40/0x90 kernel/smp.c:1057
__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+0x45f/0x16f0 arch/x86/mm/tlb.c:1451
flush_tlb_page arch/x86/include/asm/tlbflush.h:345 [inline]
ptep_clear_flush+0x148/0x170 mm/pgtable-generic.c:104
page_vma_mkclean_one.constprop.0+0x3a2/0x7b0 mm/rmap.c:1138
page_mkclean_one+0x1cd/0x2b0 mm/rmap.c:1186
__rmap_walk_file+0x383/0x680 mm/rmap.c:3064
rmap_walk_file+0x1d8/0x2a0 mm/rmap.c:3097
rmap_walk mm/rmap.c:3108 [inline]
folio_mkclean+0x2af/0x4e0 mm/rmap.c:1218
folio_clear_dirty_for_io+0x1ba/0x960 mm/page-writeback.c:2909
mpage_submit_folio+0x84/0x330 fs/ext4/inode.c:2085
mpage_process_page_bufs+0x473/0x8d0 fs/ext4/inode.c:2215
mpage_prepare_extent_to_map+0xb50/0x1920 fs/ext4/inode.c:2754
ext4_do_writepages+0x9f9/0x3ed0 fs/ext4/inode.c:2895
ext4_writepages+0x347/0x750 fs/ext4/inode.c:3043
do_writepages+0x278/0x600 mm/page-writeback.c:2571
__writeback_single_inode+0x164/0x1300 fs/fs-writeback.c:1787
writeback_sb_inodes+0x766/0x1c50 fs/fs-writeback.c:2079
__writeback_inodes_wb+0xf8/0x2d0 fs/fs-writeback.c:2155
wb_writeback+0x6f6/0xb50 fs/fs-writeback.c:2266
wb_check_old_data_flush fs/fs-writeback.c:2370 [inline]
wb_do_writeback fs/fs-writeback.c:2449 [inline]
wb_workfn+0x93f/0xc80 fs/fs-writeback.c:2477
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