syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4816/1:b..l
	(detected by 0, t=10502 jiffies, g=65737, q=150)
task:kworker/u4:1    state:R  running task     stack:24944 pid:   24 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 context_switch kernel/sched/core.c:4324 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5075
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:5532
 irqentry_exit_cond_resched kernel/entry/common.c:392 [inline]
 irqentry_exit_cond_resched kernel/entry/common.c:384 [inline]
 irqentry_exit+0x7a/0xa0 kernel/entry/common.c:428
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:635
RIP: 0010:debug_lockdep_rcu_enabled+0x23/0x30 kernel/rcu/update.c:280
Code: cc cc cc cc cc cc cc 8b 05 5e 2f c4 04 85 c0 74 21 8b 05 dc 5f c4 04 85 c0 74 17 65 48 8b 04 25 00 f0 01 00 8b 80 84 09 00 00 <85> c0 0f 94 c0 0f b6 c0 c3 cc cc cc cc 55 53 48 c7 c3 c0 5f 03 00
RSP: 0018:ffffc90000defb90 EFLAGS: 00000202
RAX: 0000000000000000 RBX: ffff888069080938 RCX: 0000000000000000
RDX: ffff888011a6b780 RSI: ffffffff889dc6f3 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff889dca2c R11: 0000000000000000 R12: ffff88802732e894
R13: dffffc0000000000 R14: ffff888031784bc0 R15: 0000000000000127
 rcu_read_unlock include/linux/rcupdate.h:706 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:771 [inline]
 batadv_iv_ogm_schedule_buff+0x758/0x1410 net/batman-adv/bat_iv_ogm.c:825
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:869 [inline]
 batadv_iv_ogm_schedule net/batman-adv/bat_iv_ogm.c:862 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x675/0x920 net/batman-adv/bat_iv_ogm.c:1723
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
task:systemd-udevd   state:R  running task     stack:22704 pid: 4816 ppid:     1 flags:0x00000000
Call Trace:
 context_switch kernel/sched/core.c:4324 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5075
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:5532
 irqentry_exit_cond_resched kernel/entry/common.c:392 [inline]
 irqentry_exit_cond_resched kernel/entry/common.c:384 [inline]
 irqentry_exit+0x7a/0xa0 kernel/entry/common.c:428
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:635
RIP: 0010:arch_local_irq_enable arch/x86/include/asm/irqflags.h:81 [inline]
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/irqflags.h:145 [inline]
RIP: 0010:seqcount_lockdep_reader_access include/linux/seqlock.h:105 [inline]
RIP: 0010:__follow_mount_rcu fs/namei.c:1424 [inline]
RIP: 0010:handle_mounts fs/namei.c:1455 [inline]
RIP: 0010:step_into+0x13e7/0x1c30 fs/namei.c:1769
Code: 00 00 00 31 d2 ff 75 08 b9 02 00 00 00 31 f6 4c 89 ef e8 3c 47 94 ff 48 8b 75 08 4c 89 ef e8 20 40 94 ff e8 db 4f b4 ff fb 59 <e9> 9e fa ff ff e8 0f 66 ae ff 49 8d 7d 20 48 b8 00 00 00 00 00 fc
RSP: 0018:ffffc900010ef880 EFLAGS: 00000206
RAX: 00000000006eeb95 RBX: ffffc900010efbb8 RCX: ffffffff81c50801
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900010ef978 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff81793958 R11: 0000000000000000 R12: 0000000000000200
R13: ffff88801a66fa80 R14: 0000000000010000 R15: ffff88801a66fa70
 walk_component+0x171/0x6a0 fs/namei.c:1945
 link_path_walk.part.0+0x712/0xc90 fs/namei.c:2266
 link_path_walk fs/namei.c:2190 [inline]
 path_lookupat+0xb7/0x830 fs/namei.c:2419
 filename_lookup+0x19f/0x560 fs/namei.c:2453
 user_path_at include/linux/namei.h:60 [inline]
 vfs_statx+0x142/0x390 fs/stat.c:195
 vfs_fstatat fs/stat.c:217 [inline]
 vfs_lstat include/linux/fs.h:3240 [inline]
 __do_sys_newlstat+0x91/0x110 fs/stat.c:372
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fe2a3fc3335
RSP: 002b:00007ffc7a92f918 EFLAGS: 00000246 ORIG_RAX: 0000000000000006
RAX: ffffffffffffffda RBX: 00005648d03b7bf0 RCX: 00007fe2a3fc3335
RDX: 00007ffc7a92f950 RSI: 00007ffc7a92f950 RDI: 00005648d03b6bf0
RBP: 00007ffc7a92fa10 R08: 00007fe2a4282228 R09: 0000000000001010
R10: 00007fe2a4281b58 R11: 0000000000000246 R12: 00005648d03b6bf0
R13: 00005648d03b6c13 R14: 00005648d03a7fe1 R15: 00005648d03a7fe3
rcu: rcu_preempt kthread starved for 10500 jiffies! g65737 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:28872 pid:   13 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:4324 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5075
 schedule+0xcf/0x270 kernel/sched/core.c:5154
 schedule_timeout+0x14a/0x250 kernel/time/timer.c:1892
 rcu_gp_fqs_loop kernel/rcu/tree.c:2005 [inline]
 rcu_gp_kthread+0xd07/0x2250 kernel/rcu/tree.c:2178
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 10043 Comm: syz-executor.0 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:queued_write_lock_slowpath+0x131/0x270 kernel/locking/qrwlock.c:76
Code: 00 00 00 00 fc ff df 49 01 c7 41 83 c6 03 41 0f b6 07 41 38 c6 7c 08 84 c0 0f 85 fe 00 00 00 8b 03 3d 00 01 00 00 74 19 f3 90 <41> 0f b6 07 41 38 c6 7c ec 84 c0 74 e8 48 89 df e8 ba c3 5c 00 eb
RSP: 0018:ffffc900022e7a60 EFLAGS: 00000006
RAX: 0000000000000300 RBX: ffffffff8bc0a080 RCX: ffffffff8159ec0a
RDX: fffffbfff1781411 RSI: 0000000000000004 RDI: ffffffff8bc0a080
RBP: 00000000000000ff R08: 0000000000000001 R09: ffffffff8bc0a083
R10: fffffbfff1781410 R11: 0000000000000000 R12: 1ffff9200045cf4d
R13: ffffffff8bc0a084 R14: 0000000000000003 R15: fffffbfff1781410
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f47b3833fe8 CR3: 0000000053a4c000 CR4: 0000000000350ee0
Call Trace:
 queued_write_lock include/asm-generic/qrwlock.h:97 [inline]
 do_raw_write_lock+0x1ce/0x280 kernel/locking/spinlock_debug.c:207
 exit_notify kernel/exit.c:667 [inline]
 do_exit+0xcaf/0x2ae0 kernel/exit.c:845
 do_group_exit+0x125/0x310 kernel/exit.c:922
 get_signal+0x42c/0x2100 kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x148/0x250 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465ef9
Code: Unable to access opcode bytes at RIP 0x465ecf.
RSP: 002b:00007f47b3834218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 000000000056c0b8 RCX: 0000000000465ef9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000056c0b8
RBP: 000000000056c0b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c0bc
R13: 00007fff11684d2f R14: 00007f47b3834300 R15: 0000000000022000