syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6736/2:b..l P6004/1:b..l
	(detected by 0, t=10502 jiffies, g=34685, q=9 ncpus=2)
task:kworker/u4:28   state:R  running task     stack:24928 pid:6004  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:lock_acquire+0x20f/0x490 kernel/locking/lockdep.c:5666
Code: 00 9c 8f 84 24 80 00 00 00 f6 84 24 81 00 00 00 02 0f 85 f5 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 66 43 c7 44 3d 09 00 00 43 c6 44 3d 0b
RSP: 0000:ffffc90006117920 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 68940da42c0b0a00
RDX: 0000000000000000 RSI: ffffffff8a8c15a0 RDI: ffffffff8adef6a0
RBP: ffffc90006117a28 R08: dffffc0000000000 R09: fffffbfff215bc49
R10: fffffbfff215bc49 R11: 1ffffffff215bc48 R12: 0000000000000000
R13: 1ffff92000c22f30 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:754 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:825 [inline]
 batadv_iv_ogm_schedule+0x413/0xe90 net/batman-adv/bat_iv_ogm.c:868
 batadv_iv_send_outstanding_bat_ogm_packet+0x72d/0x840 net/batman-adv/bat_iv_ogm.c:1712
 process_one_work+0x898/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
task:syz-executor    state:R  running task     stack:27552 pid:6736  ppid:6165   flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:seqcount_lockdep_reader_access+0x17a/0x1c0 include/linux/seqlock.h:105
Code: ff 4d 85 ed 75 16 e8 d5 15 94 ff eb 15 e8 ce 15 94 ff e8 59 a9 29 08 4d 85 ed 74 ea e8 bf 15 94 ff fb 48 c7 04 24 0e 36 e0 45 <4b> c7 04 27 00 00 00 00 66 43 c7 44 27 09 00 00 43 c6 44 27 0b 00
RSP: 0000:ffffc900033c7880 EFLAGS: 00000293
RAX: ffffffff81eca8a1 RBX: 0000000000000000 RCX: ffff88805365d940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900033c7940 R08: dffffc0000000000 R09: fffffbfff215bc5d
R10: fffffbfff215bc5d R11: 1ffffffff215bc5c R12: dffffc0000000000
R13: 0000000000000200 R14: ffffffff81ec837c R15: 1ffff92000678f10
 read_seqbegin include/linux/seqlock.h:893 [inline]
 read_seqbegin_or_lock include/linux/seqlock.h:1187 [inline]
 prepend_path+0x30c/0xc20 fs/d_path.c:170
 d_absolute_path+0x9e/0x140 fs/d_path.c:233
 tomoyo_get_absolute_path security/tomoyo/realpath.c:101 [inline]
 tomoyo_realpath_from_path+0x2d5/0x5d0 security/tomoyo/realpath.c:271
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x1fd/0x550 security/tomoyo/file.c:822
 tomoyo_path_symlink+0xa0/0xe0 security/tomoyo/tomoyo.c:199
 security_path_symlink+0xdc/0x130 security/security.c:1198
 do_symlinkat+0x104/0x3f0 fs/namei.c:4495
 __do_sys_symlinkat fs/namei.c:4517 [inline]
 __se_sys_symlinkat fs/namei.c:4514 [inline]
 __x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4514
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb13698e167
RSP: 002b:00007ffd544d5218 EFLAGS: 00000206 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb13698e167
RDX: 00007fb136a136da RSI: 00000000ffffff9c RDI: 00007ffd544d52b0
RBP: 00007ffd544d525c R08: 0000000000000013 R09: 00007ffd544d4f67
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000015
R13: 00000000000927c0 R14: 000000000003e57a R15: 00007ffd544d52b0
 </TASK>
rcu: rcu_preempt kthread starved for 10557 jiffies! g34685 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:27840 pid:16    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
 schedule+0xb9/0x180 kernel/sched/core.c:6637
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1965
 rcu_gp_fqs_loop+0x2f2/0x1310 kernel/rcu/tree.c:1706
 rcu_gp_kthread+0x95/0x380 kernel/rcu/tree.c:1905
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:741