syzbot

GRED: Unable to relocate VQ 0x0 after dequeue, screwing up backlog
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 ticks this GP) idle=81ac/1/0x4000000000000000 softirq=31169/31169 fqs=2
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7315/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=34753, q=326 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5929 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:84 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:127 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:178 [inline]
RIP: 0010:kasan_check_range+0x92/0x290 mm/kasan/generic.c:187
Code: 89 f4 4d 29 dc 49 83 fc 10 7f 29 4d 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb 41 80 3b 00 0f 85 cc 01 00 00 49 ff c3 <48> ff c3 75 ee e9 21 01 00 00 44 89 dd 83 e5 07 0f 84 b5 00 00 00
RSP: 0018:ffffc90000007828 EFLAGS: 00000082
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: ffffffff8166fe80
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff90da7500
RBP: ffffc90000007aa8 R08: ffffffff90da7507 R09: 1ffffffff21b4ea0
R10: dffffc0000000000 R11: fffffbfff21b4ea1 R12: 0000000000000001
R13: ffff888027043c00 R14: fffffbfff21b4ea1 R15: 1ffffffff21b4ea0
FS:  00007fe53139d880(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f634a5156c0 CR3: 0000000025051000 CR4: 00000000003506f0
Call Trace:
 <IRQ>
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 hlock_class kernel/locking/lockdep.c:228 [inline]
 check_wait_context kernel/locking/lockdep.c:4773 [inline]
 __lock_acquire+0x560/0x7c80 kernel/locking/lockdep.c:5087
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
 debug_object_activate+0x6c/0x4b0 lib/debugobjects.c:709
 debug_hrtimer_activate kernel/time/hrtimer.c:450 [inline]
 debug_activate kernel/time/hrtimer.c:505 [inline]
 enqueue_hrtimer+0x30/0x370 kernel/time/hrtimer.c:1108
 __run_hrtimer kernel/time/hrtimer.c:1767 [inline]
 __hrtimer_run_queues+0x637/0xc40 kernel/time/hrtimer.c:1814
 hrtimer_interrupt+0x3c9/0x9c0 kernel/time/hrtimer.c:1876
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1077 [inline]
 __sysvec_apic_timer_interrupt+0xfb/0x3b0 arch/x86/kernel/apic/apic.c:1094
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:218 [inline]
RIP: 0010:unwind_next_frame+0x264/0x2970 arch/x86/kernel/unwind_orc.c:494
Code: ff df 0f b6 04 18 84 c0 0f 85 de 21 00 00 45 8b 6d 00 44 89 f8 ff c0 48 8d 2c 85 98 f4 71 8f 48 89 e8 48 c1 e8 03 0f b6 04 18 <84> c0 0f 85 d8 21 00 00 8b 6d 00 ff c5 4b 8d 44 6d 00 48 8d 84 00
RSP: 0018:ffffc900049ef438 EFLAGS: 00000a07
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff888027043c00 RSI: 000000000000ed10 RDI: 000000000009a000
RBP: ffffffff8f75a8dc R08: ffffc900049ef5d0 R09: 0000000000000008
R10: 0000000000000004 R11: 0000000000000000 R12: ffffc900049ef508
R13: 0000000000031138 R14: ffffc900049ef53d R15: 000000000000ed10
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0xb4/0x240 mm/slab_common.c:1020
 kmalloc include/linux/slab.h:604 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 tomoyo_encode2 security/tomoyo/realpath.c:45 [inline]
 tomoyo_encode+0x28b/0x540 security/tomoyo/realpath.c:80
 tomoyo_realpath_from_path+0x592/0x5d0 security/tomoyo/realpath.c:283
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x20f/0x4b0 security/tomoyo/file.c:822
 security_inode_getattr+0xd3/0x120 security/security.c:2153
 vfs_getattr fs/stat.c:173 [inline]
 vfs_statx+0x15f/0x6d0 fs/stat.c:248
 vfs_fstatat+0x12a/0x1b0 fs/stat.c:299
 __do_sys_newfstatat fs/stat.c:463 [inline]
 __se_sys_newfstatat fs/stat.c:457 [inline]
 __x64_sys_newfstatat+0x117/0x190 fs/stat.c:457
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe530d11b0a
Code: 48 8b 15 f1 f2 0d 00 f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 41 89 ca b8 06 01 00 00 0f 05 <3d> 00 f0 ff ff 77 07 31 c0 c3 0f 1f 40 00 48 8b 15 b9 f2 0d 00 f7
RSP: 002b:00007fffcd2cab08 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 000000000000000e RCX: 00007fe530d11b0a
RDX: 00007fffcd2cab10 RSI: 00007fffcd2cabe0 RDI: 00000000ffffff9c
RBP: 00007fffcd2cbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffcd2cc040
R13: 0000000000000000 R14: 000055d22b93a100 R15: 000055d22b93a140
 </TASK>
task:syz-executor    state:R  running task     stack:21736 pid:7315  ppid:7305   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
 preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
 _raw_spin_unlock+0x3a/0x40 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:391 [inline]
 copy_pte_range mm/memory.c:1106 [inline]
 copy_pmd_range mm/memory.c:1167 [inline]
 copy_pud_range mm/memory.c:1204 [inline]
 copy_p4d_range mm/memory.c:1228 [inline]
 copy_page_range+0x2b7c/0x3600 mm/memory.c:1322
 dup_mmap kernel/fork.c:764 [inline]
 dup_mm kernel/fork.c:1692 [inline]
 copy_mm+0x112a/0x1c20 kernel/fork.c:1741
 copy_process+0x16d3/0x3d70 kernel/fork.c:2506
 kernel_clone+0x21b/0x840 kernel/fork.c:2914
 __do_sys_clone kernel/fork.c:3057 [inline]
 __se_sys_clone kernel/fork.c:3041 [inline]
 __x64_sys_clone+0x18c/0x1e0 kernel/fork.c:3041
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6349785613
RSP: 002b:00007ffef43f0458 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6349785613
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000001
R10: 000055558c9157d0 R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000927c0 R14: 0000000000036146 R15: 00007ffef43f05f0
 </TASK>
rcu: rcu_preempt kthread starved for 10495 jiffies! g34753 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:26728 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 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:
CPU: 1 PID: 35 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:311 [inline]
RIP: 0010:smp_call_function_many_cond+0xde4/0x1130 kernel/smp.c:855
Code: 89 ee 83 e6 01 31 ff e8 da d6 0a 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 15 d3 0a 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 f9 d2 0a 00 eb e4 44
RSP: 0018:ffffc90000abf780 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 1ffff110171c8791 RCX: ffff88801ce51e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90000abf900 R08: ffffffff90da7507 R09: 1ffffffff21b4ea0
R10: dffffc0000000000 R11: fffffbfff21b4ea1 R12: ffff8880b8e43c88
R13: dffffc0000000000 R14: ffff8880b8f3d348 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa40fd156c0 CR3: 000000000cb30000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1022
 on_each_cpu include/linux/smp.h:71 [inline]
 text_poke_sync arch/x86/kernel/alternative.c:2222 [inline]
 text_poke_bp_batch+0x318/0x930 arch/x86/kernel/alternative.c:2432
 text_poke_flush arch/x86/kernel/alternative.c:2623 [inline]
 text_poke_finish+0x30/0x50 arch/x86/kernel/alternative.c:2630
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x123/0x240 kernel/jump_label.c:207
 static_key_enable+0x1a/0x20 kernel/jump_label.c:220
 toggle_allocation_gate+0xaa/0x250 mm/kfence/core.c:831
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 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>