syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P2021/1:b..l
rcu: 	(detected by 0, t=10502 jiffies, g=208897, q=814 ncpus=1)
task:syz.1.12725     state:R  running task     stack:23144 pid:2021  tgid:2021  ppid:5830   task_flags:0x40064c flags:0x00080001
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6908
 preempt_schedule_irq+0x50/0x90 kernel/sched/core.c:7235
 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:__kasan_check_read+0x8/0x20 mm/kasan/shadow.c:31
Code: fe 90 0f 0b 90 48 83 c4 60 5b 5d 41 5c e9 00 74 1c 09 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 0c 24 <89> f6 31 d2 e9 0f f3 ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f
RSP: 0018:ffffc90004aef298 EFLAGS: 00000293
RAX: 0000000000000000 RBX: ffffea000225d640 RCX: ffffffff824292e6
RDX: ffff88806ad91e80 RSI: 0000000000000008 RDI: ffffea000225d640
RBP: 1ffff9200095de5e R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88805b1c6680 R14: dffffc0000000000 R15: ffffea000225d648
 instrument_atomic_read include/linux/instrumented.h:82 [inline]
 _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:141 [inline]
 folio_test_head include/linux/page-flags.h:844 [inline]
 folio_test_large include/linux/page-flags.h:865 [inline]
 folio_nr_pages include/linux/mm.h:2477 [inline]
 find_lock_entries+0x306/0x1130 mm/filemap.c:2176
 shmem_undo_range+0x212/0x1570 mm/shmem.c:1131
 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+0x8b8/0x2b60 kernel/exit.c:976
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1118
 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: 0033:0x21000
RSP: 002b:000000000000000a EFLAGS: 00010282
RAX: 0000000000000003 RBX: 00007f7cf6a15fa0 RCX: 00007f7cf679c799
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000020003b4a
RBP: 00007f7cf6832bd9 R08: 0000000000000002 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7cf6a16038 R14: 00007f7cf6a15fa0 R15: 00007ffc2aea1b28
 </TASK>
rcu: rcu_preempt kthread starved for 510 jiffies! g208897 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:26504 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00080000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7005
 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+0x754/0xd80 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: 3410 Comm: kworker/R-bat_e Tainted: G     U    I  L      syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: bat_events batadv_tt_purge
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:114 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:128 [inline]
RIP: 0010:lock_acquire kernel/locking/lockdep.c:5864 [inline]
RIP: 0010:lock_acquire+0x17f/0x380 kernel/locking/lockdep.c:5825
Code: 00 65 8b 05 ab 18 29 12 85 c0 0f 85 ae 00 00 00 65 48 8b 05 2b d1 28 12 8b 90 54 0b 00 00 85 d2 0f 85 98 00 00 00 9c 8f 04 24 <fa> 48 c7 c7 48 ee f6 8d e8 04 a6 a8 09 45 89 e8 44 89 e1 89 da 65
RSP: 0018:ffffc90000006e78 EFLAGS: 00000246
RAX: ffff888034208000 RBX: 0000000000000000 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffffffff81b7aeb1 RDI: fffffbfff1cfce84
RBP: ffffffff8e7e7420 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000200 R11: 000000000000c8b3 R12: 0000000000000002
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88812434d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056456af3a608 CR3: 000000007eb5c000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 rcu_read_lock include/linux/rcupdate.h:850 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
 unwind_next_frame+0xd1/0x1ea0 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:4542 [inline]
 slab_alloc_node mm/slub.c:4869 [inline]
 kmem_cache_alloc_noprof+0x241/0x6e0 mm/slub.c:4876
 skb_clone+0x190/0x400 net/core/skbuff.c:2120
 deliver_clone net/bridge/br_forward.c:125 [inline]
 maybe_deliver+0xd4/0x180 net/bridge/br_forward.c:191
 br_flood+0x193/0x650 net/bridge/br_forward.c:238
 br_handle_frame_finish+0xff0/0x1f60 net/bridge/br_input.c:229
 br_nf_hook_thresh+0x30d/0x420 net/bridge/br_netfilter_hooks.c:1167
 br_nf_pre_routing_finish_ipv6+0x769/0xfb0 net/bridge/br_netfilter_ipv6.c:154
 NF_HOOK include/linux/netfilter.h:318 [inline]
 br_nf_pre_routing_ipv6+0x39c/0x8b0 net/bridge/br_netfilter_ipv6.c:184
 br_nf_pre_routing+0x93b/0x1510 net/bridge/br_netfilter_hooks.c:508
 nf_hook_entry_hookfn include/linux/netfilter.h:158 [inline]
 nf_hook_bridge_pre net/bridge/br_input.c:291 [inline]
 br_handle_frame+0xcdd/0x1520 net/bridge/br_input.c:442
 __netif_receive_skb_core.constprop.0+0x6c5/0x3550 net/core/dev.c:6051
 __netif_receive_skb_one_core+0xb0/0x1e0 net/core/dev.c:6162
 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6277
 process_backlog+0x37a/0x1580 net/core/dev.c:6628
 __napi_poll.constprop.0+0xaf/0x450 net/core/dev.c:7692
 napi_poll net/core/dev.c:7755 [inline]
 net_rx_action+0xa40/0xf20 net/core/dev.c:7912
 handle_softirqs+0x1eb/0x9e0 kernel/softirq.c:622
 do_softirq kernel/softirq.c:523 [inline]
 do_softirq+0xac/0xe0 kernel/softirq.c:510
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0xf8/0x120 kernel/softirq.c:450
 spin_unlock_bh include/linux/spinlock.h:395 [inline]
 batadv_tt_global_purge net/batman-adv/translation-table.c:2250 [inline]
 batadv_tt_purge+0x25d/0xbd0 net/batman-adv/translation-table.c:3510
 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
 process_scheduled_works kernel/workqueue.c:3358 [inline]
 rescuer_thread+0x902/0x1490 kernel/workqueue.c:3582
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>