syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3421/1:b..l P6594/1:b..l
rcu: 	(detected by 1, t=10502 jiffies, g=16985, q=531 ncpus=2)
task:dhcpcd-run-hook state:R  running task     stack:24232 pid:6594  ppid:5433   flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:check_region_inline mm/kasan/generic.c:172 [inline]
RIP: 0010:kasan_check_range+0x29/0x290 mm/kasan/generic.c:187
Code: cc 66 0f 1f 00 b0 01 48 85 f6 0f 84 b4 01 00 00 55 41 57 41 56 41 55 41 54 53 4c 8d 04 37 49 39 f8 0f 82 13 02 00 00 49 89 f9 <49> c1 e9 2f 41 81 f9 ff ff 01 00 0f 82 ff 01 00 00 49 89 ff 49 c1
RSP: 0018:ffffc9000b95f328 EFLAGS: 00000202
RAX: ffffffff8a73d701 RBX: ffff88802bbdd000 RCX: ffffffff8a73d718
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff976dbf40
RBP: ffffc9000b95f510 R08: ffffffff976dbf44 R09: ffffffff976dbf40
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88803bbff100
R13: ffff88807b4bea80 R14: 0000000000000001 R15: 0000000000000300
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_inc include/linux/atomic/atomic-instrumented.h:435 [inline]
 mt_validate_nulls lib/maple_tree.c:7188 [inline]
 mt_validate+0x3e58/0x4400 lib/maple_tree.c:7237
 validate_mm+0xc6/0x450 mm/mmap.c:288
 __split_vma+0xad4/0xc60 mm/mmap.c:2425
 do_vmi_align_munmap+0x3d0/0x16d0 mm/mmap.c:2514
 do_vmi_munmap+0x252/0x2d0 mm/mmap.c:2660
 __mmap_region mm/mmap.c:2710 [inline]
 mmap_region+0x773/0x2000 mm/mmap.c:2941
 do_mmap+0x92c/0x10a0 mm/mmap.c:1385
 vm_mmap_pgoff+0x1c4/0x3f0 mm/util.c:556
 ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fc66830d242
RSP: 002b:00007ffe7c8cd458 EFLAGS: 00000206 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007fc668012000 RCX: 00007fc66830d242
RDX: 0000000000000001 RSI: 0000000000008000 RDI: 00007fc668012000
RBP: 0000000000000812 R08: 0000000000000003 R09: 0000000000024000
R10: 0000000000000812 R11: 0000000000000206 R12: 00007ffe7c8cd4e0
R13: 00007fc6682eaab0 R14: 00007ffe7c8cd8d0 R15: 00000fffcf919a8e
 </TASK>
task:kworker/u4:9    state:R  running task     stack:23288 pid:3421  ppid:2      flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_irq+0xbf/0x150 kernel/sched/core.c:7010
 irqentry_exit+0x67/0x70 kernel/entry/common.c:438
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__preempt_count_add arch/x86/include/asm/preempt.h:80 [inline]
RIP: 0010:rcu_is_watching+0x0/0xb0 kernel/rcu/tree.c:699
Code: 84 1d ff ff ff eb 8a e8 1e 65 15 09 48 c7 c7 40 89 13 8d 4c 89 f6 e8 bf 68 ec 02 e9 44 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 <f3> 0f 1e fa 41 57 41 56 53 65 ff 05 d8 d0 92 7e e8 db 7a 15 09 89
RSP: 0018:ffffc9000c8a7ae8 EFLAGS: 00000202
RAX: ffffffff8a4e2250 RBX: ffffffff8a4e24f0 RCX: 0000000000000000
RDX: ffff88802df11e00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffff8880308c5318 R08: dffffc0000000000 R09: 1ffffffff2238aa0
R10: dffffc0000000000 R11: fffffbfff2238aa1 R12: dffffc0000000000
R13: 1ffff110061ceaf3 R14: 0000000000000001 R15: ffff888030e74c80
 rcu_read_lock include/linux/rcupdate.h:787 [inline]
 batadv_nc_process_nc_paths+0xfa/0x390 net/batman-adv/network-coding.c:687
 batadv_nc_worker+0x429/0x610 net/batman-adv/network-coding.c:728
 process_one_work kernel/workqueue.c:2653 [inline]
 process_scheduled_works+0xa5d/0x15d0 kernel/workqueue.c:2730
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2811
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: rcu_preempt kthread starved for 10493 jiffies! g16985 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:26960 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5381 [inline]
 __schedule+0x1553/0x45a0 kernel/sched/core.c:6700
 schedule+0xbd/0x170 kernel/sched/core.c:6774
 schedule_timeout+0x188/0x2d0 kernel/time/timer.c:2168
 rcu_gp_fqs_loop+0x313/0x1590 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x9d/0x3b0 kernel/rcu/tree.c:1866
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:pv_native_safe_halt+0xf/0x10 arch/x86/kernel/paravirt.c:148
Code: 39 21 02 c3 cc cc cc cc cc cc cc f3 0f 1e fa 0f 0b 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 66 90 0f 00 2d e3 f3 41 00 fb f4 <c3> 66 0f 1f 00 55 41 57 41 56 41 54 53 50 8b 2f eb 2e 41 89 de 80
RSP: 0018:ffffc90000187de0 EFLAGS: 000002c6
RAX: 6b4233f8315a1d00 RBX: ffffffff8162aa0d RCX: 6b4233f8315a1d00
RDX: 0000000000000001 RSI: ffffffff8acac9e0 RDI: ffffffff8b1c8e60
RBP: ffffc90000187f20 R08: ffff8880b8f36b2b R09: 1ffff110171e6d65
R10: dffffc0000000000 R11: ffffed10171e6d66 R12: 1ffff92000030fc8
R13: dffffc0000000000 R14: 1ffff110036cd780 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564101c7aa38 CR3: 000000000cf32000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:108 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:753
 default_idle_call+0x6c/0xa0 kernel/sched/idle.c:97
 cpuidle_idle_call kernel/sched/idle.c:178 [inline]
 do_idle+0x33d/0x590 kernel/sched/idle.c:302
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:401
 start_secondary+0xee/0xf0 arch/x86/kernel/smpboot.c:323
 secondary_startup_64_no_verify+0x179/0x17b
 </TASK>