syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6027/1:b..l
rcu: 	(detected by 0, t=16455 jiffies, g=10341, q=841 ncpus=2)
task:syz-executor    state:R  running task     stack:24736 pid:6027  tgid:6027  ppid:5828   flags:0x00000002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 preempt_schedule_irq+0xfb/0x1c0 kernel/sched/core.c:7078
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_release+0x658/0xa30 kernel/locking/lockdep.c:5874
Code: 3c 3b 00 74 08 4c 89 f7 e8 d5 fb 8a 00 f6 84 24 91 00 00 00 02 75 77 41 f7 c5 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 4b c7 44 27 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900030776e0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff9200060eeee RCX: ffffc90003077703
RDX: 0000000000000001 RSI: ffffffff8c0aaae0 RDI: ffffffff8c5fb0a0
RBP: ffffc90003077808 R08: ffffffff901a4a77 R09: 1ffffffff203494e
R10: dffffc0000000000 R11: fffffbfff203494f R12: 1ffff9200060eee8
R13: 0000000000000246 R14: ffffc90003077770 R15: dffffc0000000000
 rcu_lock_release include/linux/rcupdate.h:347 [inline]
 rcu_read_unlock include/linux/rcupdate.h:880 [inline]
 get_task_pid+0x27f/0x310 kernel/pid.c:456
 proc_pid_make_inode+0x9f/0x130 fs/proc/base.c:1964
 proc_pid_make_base_inode fs/proc/base.c:2001 [inline]
 proc_pid_instantiate+0x54/0x2b0 fs/proc/base.c:3486
 proc_pid_lookup+0x31f/0x480 fs/proc/base.c:3530
 proc_root_lookup+0x1f/0x50 fs/proc/root.c:325
 __lookup_slow+0x28c/0x3f0 fs/namei.c:1791
 lookup_slow+0x53/0x70 fs/namei.c:1808
 walk_component+0x2e1/0x410 fs/namei.c:2112
 link_path_walk+0x797/0xea0 fs/namei.c:2474
 path_lookupat+0xa9/0x450 fs/namei.c:2633
 filename_lookup+0x2a3/0x670 fs/namei.c:2663
 do_readlinkat+0xf0/0x3a0 fs/stat.c:562
 __do_sys_readlink fs/stat.c:599 [inline]
 __se_sys_readlink fs/stat.c:596 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:596
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7952b9aa56
RSP: 002b:00007fffa63d0fd0 EFLAGS: 00000202 ORIG_RAX: 0000000000000059
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f7952b9aa56
RDX: 0000000000001000 RSI: 00007fffa63d0fd0 RDI: 00007f7952c2b918
RBP: 00007fffa63d0fd0 R08: 0000000000000000 R09: 00007f7952c2bfb4
R10: 00007fffa63d2060 R11: 0000000000000202 R12: 00007fffa63d21b0
R13: 00007fffa63d2198 R14: 00007fffa63d2130 R15: 00007fffa63d2128
 </TASK>
rcu: rcu_preempt kthread starved for 16455 jiffies! g10341 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:25784 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0x1850/0x4c30 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6848
 schedule_timeout+0x15a/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x2df/0x1330 kernel/rcu/tree.c:2045
 rcu_gp_kthread+0xa7/0x3b0 kernel/rcu/tree.c:2247
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:1 Not tainted 6.13.0-rc6-syzkaller-00967-g7dc8f809b87d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: bat_events batadv_bla_periodic_work
RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5853
Code: 2b 00 74 08 4c 89 f7 e8 8a 27 8b 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25
RSP: 0018:ffffc900001178a0 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 1ffff92000022f20 RCX: ffff88801cace4d8
RDX: dffffc0000000000 RSI: ffffffff8c0aaae0 RDI: ffffffff8c5fb0a0
RBP: ffffc900001179e8 R08: ffffffff942c0887 R09: 1ffffffff2858110
R10: dffffc0000000000 R11: fffffbfff2858111 R12: 1ffff92000022f1c
R13: dffffc0000000000 R14: ffffc90000117900 R15: 0000000000000246
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f79538a8740 CR3: 0000000024462000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 </IRQ>
 <TASK>
 rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 rcu_read_lock include/linux/rcupdate.h:849 [inline]
 batadv_bla_purge_claims+0x11d/0x6c0 net/batman-adv/bridge_loop_avoidance.c:1290
 batadv_bla_periodic_work+0xb5/0xaf0 net/batman-adv/bridge_loop_avoidance.c:1445
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>