GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (2 GPs behind) idle=ec74/1/0x4000000000000000 softirq=26269/26270 fqs=22
rcu: 	(detected by 1, t=10506 jiffies, g=26513, q=442 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 8080 Comm: syz.1.568 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:preempt_count_sub+0x22/0x160 kernel/sched/core.c:5882
Code: 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 c7 c0 80 13 1a 9b 53 89 fb 48 ba 00 00 00 00 00 fc ff df 48 89 c1 83 e0 07 48 c1 e9 03 <83> c0 03 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 d9 00 00 00 8b 0d 75
RSP: 0018:ffffc90000007d78 EFLAGS: 00000802
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 1ffffffff3634270
RDX: dffffc0000000000 RSI: 0000000000000004 RDI: 0000000000000001
RBP: 0000000000000006 R08: 0000000000000000 R09: fffffbfff367bf25
R10: ffffffff9b3df92b R11: 0000000000000001 R12: 0000000000000001
R13: dffffc0000000000 R14: ffff88802db06300 R15: 1ffff92000000fb6
FS:  00007f1ffc0376c0(0000) GS:ffff888124376000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000dd030 CR3: 0000000034cfa000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:179 [inline]
 _raw_spin_unlock_irqrestore+0x3b/0x80 kernel/locking/spinlock.c:198
 debug_object_deactivate+0x2e4/0x3b0 lib/debugobjects.c:905
 debug_hrtimer_deactivate kernel/time/hrtimer.c:490 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1898 [inline]
 __hrtimer_run_queues+0x2f0/0xa00 kernel/time/hrtimer.c:1994
 hrtimer_interrupt+0x3e5/0x940 kernel/time/hrtimer.c:2113
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 __sysvec_apic_timer_interrupt+0x10b/0x460 arch/x86/kernel/apic/apic.c:1067
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0x9e/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:prepare_alloc_pages+0x3e7/0x5f0 mm/page_alloc.c:4989
Code: 00 65 48 8b 0d f2 7d a3 11 65 66 f7 05 01 7e a3 11 01 ff 75 22 48 b8 00 00 00 00 00 fc ff df 4c 89 e6 48 c1 ee 03 80 3c 06 00 <0f> 85 e7 01 00 00 48 83 7b 08 00 74 35 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc900078870d8 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc90007887290 RCX: ffff8880338fca00
RDX: 0000000000000000 RSI: 1ffff92000f10e53 RDI: ffffc900078872a8
RBP: 0000000000140cca R08: ffffc90007887290 R09: ffffc90007887240
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90007887298
R13: ffffc900078872ac R14: 0000000000000008 R15: ffffc90007887230
 __alloc_frozen_pages_noprof+0x19a/0x2bc0 mm/page_alloc.c:5215
 alloc_pages_mpol+0x1fb/0x540 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x36/0x260 mm/mempolicy.c:2509
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1933
 shmem_alloc_and_add_folio+0x371/0xd40 mm/shmem.c:1975
 shmem_get_folio_gfp+0x6ab/0x1900 mm/shmem.c:2564
 shmem_fault+0x1f9/0xa20 mm/shmem.c:2765
 __do_fault+0x10b/0x440 mm/memory.c:5458
 do_read_fault mm/memory.c:5893 [inline]
 do_fault+0xa99/0x1750 mm/memory.c:6027
 do_pte_missing mm/memory.c:4550 [inline]
 handle_pte_fault mm/memory.c:6411 [inline]
 __handle_mm_fault+0x187d/0x2a00 mm/memory.c:6549
 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1178/0x32a0 mm/gup.c:1428
 populate_vma_page_range+0x267/0x3f0 mm/gup.c:1860
 __mm_populate+0x107/0x3a0 mm/gup.c:1963
 mm_populate include/linux/mm.h:4137 [inline]
 vm_mmap_pgoff+0x37f/0x470 mm/util.c:586
 ksys_mmap_pgoff+0xe4/0x610 mm/mmap.c:606
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1ffb19cdd9
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:00007f1ffc037028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f1ffb415fa0 RCX: 00007f1ffb19cdd9
RDX: b635773f06ebbeee RSI: 0000000000b36000 RDI: 0000200000000000
RBP: 00007f1ffb232d69 R08: ffffffffffffffff R09: 0000000070f9a000
R10: 0000000000008031 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1ffb416038 R14: 00007f1ffb415fa0 R15: 00007ffe744bb358
 </TASK>
rcu: rcu_preempt kthread starved for 10395 jiffies! g26513 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:28904 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x10e9/0x6820 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7282
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1a9/0x900 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x179/0x230 kernel/rcu/tree.c:2297
 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
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 UID: 0 PID: 5617 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:handle_softirqs+0x1ad/0xa00 kernel/softirq.c:608
Code: 30 44 88 74 24 23 45 89 ee 48 c7 c7 00 77 ad 8b e8 08 cb c1 09 31 d2 65 66 89 15 56 72 42 12 e8 c9 9f 48 00 fb bb ff ff ff ff <49> c7 c4 c0 a0 40 8e 41 0f bc de 83 c3 01 0f 85 a4 00 00 00 e9 47
RSP: 0000:ffffc90000a08f20 EFLAGS: 00000206
RAX: 00000000007fe61e RBX: 00000000ffffffff RCX: 0000000000000004
RDX: 0000000000000000 RSI: ffffffff8df1f719 RDI: ffffffff8c1c3500
RBP: 0000000100001306 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 000000000000000a
R13: 0000000000000100 R14: 0000000000000100 R15: 1ffff920001411ec
FS:  000055555ace3500(0000) GS:ffff888124476000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555acfea48 CR3: 0000000059efa000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x162/0x210 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
 sysvec_apic_timer_interrupt+0xa3/0xc0 arch/x86/kernel/apic/apic.c:1061
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0x589/0x1700 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 89 7c 0c 00 f3 90 <41> 0f b6 45 00 41 38 c4 7c 08 84 c0 0f 85 63 0f 00 00 8b 45 08 31
RSP: 0000:ffffc90003337888 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81fc0f3d
RDX: ffff88807a402500 RSI: ffffffff81fc0f17 RDI: ffff88807a402500
RBP: ffff8880b8443320 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000003
R13: ffffed1017088665 R14: 0000000000000001 R15: ffff8880b853c5c0
 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
 wp_page_copy mm/memory.c:3925 [inline]
 do_wp_page+0x12a4/0x4350 mm/memory.c:4320
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault+0x1ab6/0x2a00 mm/memory.c:6549
 handle_mm_fault+0x36d/0xa20 mm/memory.c:6718
 do_user_addr_fault+0x5a3/0x12f0 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6f/0xd0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f28fb561960
Code: c4 28 00 48 8d 0c 1e 49 39 d0 49 89 48 60 0f 95 c2 48 29 d8 0f b6 d2 48 83 c8 01 48 c1 e2 02 48 09 da 48 83 ca 01 48 89 56 08 <48> 89 41 08 48 8d 4e 10 eb b0 48 8d 0d 4f da 0c 00 ba 9e 10 00 00
RSP: 002b:00007ffd4f566bd0 EFLAGS: 00010206
RAX: 00000000000185c1 RBX: 0000000000008040 RCX: 000055555acfea40
RDX: 0000000000008041 RSI: 000055555acf6a00 RDI: 0000000000000004
RBP: 0000000000000802 R08: 00007f28fb7ede20 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000008030
R13: 0000000000000000 R14: 00007f28fb7ede80 R15: 0000000000000000
 </TASK>