[syzbot] [mm?] INFO: rcu detected stall in __dentry_kill

[syzbot] [mm?] INFO: rcu detected stall in __dentry_kill

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    2f9339c052bd Merge tag 'spi-fix-v7.0-rc1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ee2d5a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=af6ed0125ed44356
dashboard link: https://syzkaller.appspot.com/bug?extid=f8ccdac0a7eede0e1ae5
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/80058c3aa6af/disk-2f9339c0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b80f7bb94c82/vmlinux-2f9339c0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2aca3560fd76/bzImage-2f9339c0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8ccdac0a7eede0e1ae5@syzkaller.appspotmail.com

bridge0: received packet on veth0_to_bridge with own address as source address (addr:8a:88:71:a0:4a:94, vlan:0)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P10337/1:b..l P10386/1:b..l
rcu: 	(detected by 1, t=10503 jiffies, g=42749, q=1178 ncpus=2)
task:syz.1.1104      state:R  running task     stack:26792 pid:10386 tgid:10385 ppid:5832   task_flags:0x40054c flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x60e0 kernel/sched/core.c:6907
 preempt_schedule_common+0x42/0xc0 kernel/sched/core.c:7091
 preempt_schedule_thunk+0x16/0x30 arch/x86/entry/thunk.S:12
 __raw_spin_unlock include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
 spin_unlock include/linux/spinlock.h:389 [inline]
 zap_pte_range mm/memory.c:1959 [inline]
 zap_pmd_range mm/memory.c:2021 [inline]
 zap_pud_range mm/memory.c:2049 [inline]
 zap_p4d_range mm/memory.c:2070 [inline]
 unmap_page_range+0x152f/0x4840 mm/memory.c:2091
 unmap_single_vma+0x153/0x240 mm/memory.c:2133
 unmap_vmas+0x295/0x590 mm/memory.c:2171
 exit_mmap+0x1ef/0xa30 mm/mmap.c:1302
 __mmput+0x12a/0x410 kernel/fork.c:1174
 mmput+0x67/0x80 kernel/fork.c:1197
 exit_mm kernel/exit.c:581 [inline]
 do_exit+0x78a/0x2aa0 kernel/exit.c:959
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x4a0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x668/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f663f59c799
RSP: 002b:00007f6640521028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: fffffffffffffffc RBX: 00007f663f815fa0 RCX: 00007f663f59c799
RDX: 0000000000000017 RSI: ffffffffffff0005 RDI: 0000000000000000
RBP: 00007f663f632bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f663f816038 R14: 00007f663f815fa0 R15: 00007ffe16d21cd8
 </TASK>
task:syz.3.1088      state:R  running task     stack:26216 pid:10337 tgid:10337 ppid:5827   task_flags:0x40064c flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x60e0 kernel/sched/core.c:6907
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7234
 irqentry_exit+0x17b/0x670 kernel/entry/common.c:239
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__sanitizer_cov_trace_pc+0x3f/0x70 kernel/kcov.c:217
Code: 05 12 a9 00 01 ff 00 74 1b f6 c4 01 74 07 a9 00 00 ff 00 74 05 e9 d1 30 88 09 8b 82 54 16 00 00 85 c0 74 f1 8b 82 30 16 00 00 <83> f8 02 75 e6 48 8b 8a 38 16 00 00 8b 92 34 16 00 00 48 8b 01 48
RSP: 0000:ffffc90004ba7188 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffea0001354c80 RCX: ffffffff827e8e11
RDX: ffff888020f90000 RSI: ffffffff827e8b0d RDI: ffff888020f90000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000001640274 R14: 0000000000000000 R15: 0000000002b60289
 __update_page_owner_free_handle.isra.0+0x6d/0x4d0 mm/page_owner.c:284
 __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:1433 [inline]
 free_unref_folios+0xaea/0x1790 mm/page_alloc.c:3040
 folios_put_refs+0x53c/0x840 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x5e5/0x1570 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x39e/0xbd0 mm/shmem.c:1407
 evict+0x3c2/0xad0 fs/inode.c:846
 iput_final fs/inode.c:1966 [inline]
 iput.part.0+0x605/0xf50 fs/inode.c:2015
 iput+0x35/0x40 fs/inode.c:1981
 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467
 __dentry_kill+0x1d0/0x600 fs/dcache.c:670
 finish_dput+0x76/0x480 fs/dcache.c:879
 dput.part.0+0x456/0x570 fs/dcache.c:928
 dput+0x1f/0x30 fs/dcache.c:920
 __fput+0x519/0xb40 fs/file_table.c:477
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x829/0x2aa0 kernel/exit.c:971
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1112
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x1f8/0x670 kernel/entry/common.c:219
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x4021000
RSP: 002b:0000000000000009 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 00007f8bdda15fa0 RCX: 00007f8bdd79c799
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 00007f8bdd832bd9 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8bdda16038 R14: 00007f8bdda15fa0 R15: 00007ffe5ae86398
 </TASK>
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:8a:88:71:a0:4a:94, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:8a:88:71:a0:4a:94, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:8a:88:71:a0:4a:94, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:8a:88:71:a0:4a:94, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)


---
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Re: [syzbot] [mm?] INFO: rcu detected stall in __dentry_kill

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9772589b57e4 netlabel: validate unlabeled address and mask..
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=13230bec580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=65472e27d1590a04
dashboard link: https://syzkaller.appspot.com/bug?extid=f8ccdac0a7eede0e1ae5
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12fc5e7a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/54d0bafddbc5/disk-9772589b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82dd93b33708/vmlinux-9772589b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5ab8ee618a60/bzImage-9772589b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f8ccdac0a7eede0e1ae5@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5788/1:b.el
rcu: 	(detected by 0, t=10506 jiffies, g=15749, q=1307 ncpus=2)
task:syz-executor    state:R  running task     stack:21752 pid:5788  tgid:5788  ppid:5780   task_flags:0x400140 flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7513
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline]
 irqentry_exit+0x14f/0x8b0 kernel/entry/common.c:164
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:101 [inline]
RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:238 [inline]
RIP: 0010:unwind_next_frame+0x4d6/0x2550 arch/x86/kernel/unwind_orc.c:510
Code: 00 00 83 f8 01 4c 8b 7c 24 50 48 bd 00 00 00 00 00 fc ff df 4c 8b 6c 24 20 0f 84 86 16 00 00 e9 03 02 00 00 49 89 d5 48 89 d5 <48> 89 d8 48 29 e8 48 89 c1 48 c1 f9 02 48 c1 e8 3f 48 01 c8 48 83
RSP: 0018:ffffc90003c2f4b8 EFLAGS: 00000246
RAX: ffffffff9052f1d0 RBX: ffffffff9052f1d0 RCX: ffffffff9052f1d8
RDX: ffffffff9052f1d0 RSI: ffffffff90d3bfc2 RDI: ffffffff8c28b880
RBP: ffffffff9052f1d0 R08: 0000000000000003 R09: ffffffff8e95cc20
R10: ffffc90003c2f5d8 R11: ffffffff81b0e0e0 R12: ffffffff8243249e
R13: ffffffff9052f1d0 R14: ffffc90003c2f588 R15: ffffffff9052f1d4
 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4570 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906
 kmem_alloc_batch lib/debugobjects.c:371 [inline]
 fill_pool+0x156/0x580 lib/debugobjects.c:420
 debug_objects_fill_pool lib/debugobjects.c:752 [inline]
 debug_object_activate+0x4a3/0x580 lib/debugobjects.c:841
 debug_rcu_head_queue kernel/rcu/rcu.h:236 [inline]
 __call_rcu_common kernel/rcu/tree.c:3116 [inline]
 call_rcu+0x43/0x890 kernel/rcu/tree.c:3251
 __destroy_inode+0x2b2/0x640 fs/inode.c:369
 destroy_inode fs/inode.c:392 [inline]
 evict+0x8a7/0xb10 fs/inode.c:865
 __dentry_kill+0x1a2/0x690 fs/dcache.c:718
 finish_dput+0xc9/0x480 fs/dcache.c:927
 __fput+0x691/0xa60 fs/file_table.c:518
 fput_close_sync+0x11f/0x240 fs/file_table.c:615
 __do_sys_close fs/open.c:1507 [inline]
 __se_sys_close fs/open.c:1492 [inline]
 __x64_sys_close+0x7e/0x110 fs/open.c:1492
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efe5039bfc7
RSP: 002b:00007fff8a26cfa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007efe5039bfc7
RDX: 0000000000000000 RSI: 0000000000008933 RDI: 0000000000000005
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000004
R10: 0000000000000005 R11: 0000000000000246 R12: 00007fff8a26d03c
R13: 00007efe504334c0 R14: 00007efe51144620 R15: 00007efe504334c0
 </TASK>
rcu: rcu_preempt kthread starved for 5285 jiffies! g15749 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:27688 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5388 [inline]
 __schedule+0x1821/0x5740 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7283
 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095
 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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: 0 UID: 0 PID: 1163 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:csd_lock_wait kernel/smp.c:342 [inline]
RIP: 0010:smp_call_function_many_cond+0xfcf/0x13d0 kernel/smp.c:892
Code: 79 45 8b 2e 44 89 ee 83 e6 01 31 ff e8 aa 07 0c 00 41 83 e5 01 49 bd 00 00 00 00 00 fc ff df 75 07 e8 55 03 0c 00 eb 37 f3 90 <43> 0f b6 04 2c 84 c0 75 10 41 f7 06 01 00 00 00 74 1e e8 3a 03 0c
RSP: 0018:ffffc900058e7700 EFLAGS: 00000293
RAX: ffffffff81b9b376 RBX: ffff8880b863c388 RCX: ffff888028eb3e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900058e7840 R08: ffffffff903034f7 R09: 1ffffffff206069e
R10: dffffc0000000000 R11: fffffbfff206069f R12: 1ffff110170e81b1
R13: dffffc0000000000 R14: ffff8880b8740d88 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881252a0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7680c6904c CR3: 000000000e74a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 on_each_cpu_cond_mask+0x3f/0x80 kernel/smp.c:1057
 on_each_cpu include/linux/smp.h:72 [inline]
 smp_text_poke_sync_each_cpu arch/x86/kernel/alternative.c:2773 [inline]
 smp_text_poke_batch_finish+0x5f5/0x1160 arch/x86/kernel/alternative.c:2983
 arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
 static_key_enable_cpuslocked+0x128/0x240 kernel/jump_label.c:210
 static_key_enable+0x1a/0x20 kernel/jump_label.c:223
 toggle_allocation_gate+0xab/0x290 mm/kfence/core.c:906
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3397
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3478
 kthread+0x389/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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