rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P5911/1:b..l P16538/1:b..l
	(detected by 1, t=10502 jiffies, g=69197, q=2)
task:syz.4.2127      state:R  running task     stack:25744 pid:16538 ppid:  4197 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:__sanitizer_cov_trace_pc+0x3e/0x60 kernel/kcov.c:211
Code: e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 <48> 8b 32 48 8d 7e 01 8b 89 14 16 00 00 48 39 cf 73 08 48 89 44 f2
RSP: 0000:ffffc9000382f348 EFLAGS: 00000246
RAX: ffffffff840d4289 RBX: 1ffff92000705e88 RCX: ffff88801edbd940
RDX: ffffc9000ca81000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: ffffc9000382f440
R13: ffff88801d999498 R14: ffffea00013dc5c0 R15: 0000000000000016
 xa_entry include/linux/xarray.h:1197 [inline]
 xas_descend+0x119/0x3b0 lib/xarray.c:204
 xas_load+0xba/0x140 lib/xarray.c:240
 mapping_get_entry mm/filemap.c:1826 [inline]
 pagecache_get_page+0x1b7/0xf20 mm/filemap.c:1894
 find_get_page_flags include/linux/pagemap.h:357 [inline]
 __find_get_block_slow fs/buffer.c:202 [inline]
 __find_get_block+0x362/0x10d0 fs/buffer.c:1310
 __getblk_gfp+0x2c/0xb20 fs/buffer.c:1332
 __bread_gfp+0x28/0x380 fs/buffer.c:1381
 sb_bread include/linux/buffer_head.h:337 [inline]
 fat__get_entry fs/fat/dir.c:100 [inline]
 fat_get_entry+0x781/0xab0 fs/fat/dir.c:128
 fat_get_short_entry fs/fat/dir.c:873 [inline]
 fat_subdirs+0x113/0x220 fs/fat/dir.c:939
 fat_read_root+0x5d1/0x820 fs/fat/inode.c:1413
 fat_fill_super+0x330b/0x4a10 fs/fat/inode.c:1863
 mount_bdev+0x28a/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x247/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9eb54b634a
RSP: 002b:00007f9eb370ce58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f9eb370cee0 RCX: 00007f9eb54b634a
RDX: 0000200000000000 RSI: 00002000000002c0 RDI: 00007f9eb370cea0
RBP: 0000200000000000 R08: 00007f9eb370cee0 R09: 0000000000000400
R10: 0000000000000400 R11: 0000000000000246 R12: 00002000000002c0
R13: 00007f9eb370cea0 R14: 000000000000127a R15: 0000200000000300
 </TASK>
task:kworker/u4:46   state:R  running task     stack:21904 pid: 5911 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:__rcu_read_unlock+0x0/0xd0 kernel/rcu/tree_plugin.h:415
Code: c0 75 11 ff 03 8b 03 3d 00 00 00 40 7d 02 5b c3 0f 0b eb fa 89 d9 80 e1 07 80 c1 03 38 c1 7c e3 48 89 df e8 e2 d0 58 00 eb d9 <41> 57 41 56 41 55 41 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b
RSP: 0018:ffffc90003a9fbd8 EFLAGS: 00000293
RAX: ffffffff8994ae3f RBX: dffffc0000000000 RCX: ffff888025379dc0
RDX: 0000000000000000 RSI: ffffffff8a7a41e0 RDI: ffffffff8a7a41a0
RBP: ffff888074f6d5c0 R08: dffffc0000000000 R09: 1ffffffff203dc18
R10: dffffc0000000000 R11: fffffbfff203dc19 R12: 0000000000000041
R13: 0000000000000000 R14: ffff888064284c80 R15: ffff888074f6d5d0
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
 batadv_nc_worker+0x250/0x5c0 net/batman-adv/network-coding.c:723
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10519 jiffies! g69197 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:27440 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at default_idle+0xb/0x10 arch/x86/kernel/process.c:729