syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4286/1:b..l
	(detected by 0, t=10502 jiffies, g=38653, q=253 ncpus=2)
task:udevd           state:R  running task     stack:24160 pid:4286  ppid:3638   flags:0x00004002
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_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:mte_parent lib/maple_tree.c:521 [inline]
RIP: 0010:mte_dead_node lib/maple_tree.c:553 [inline]
RIP: 0010:mas_first_entry lib/maple_tree.c:6720 [inline]
RIP: 0010:mt_validate+0x82c/0x4c90 lib/maple_tree.c:7227
Code: f0 ff 05 a7 a3 00 0d 49 c7 c7 00 ff ff ff 4c 8b a4 24 38 01 00 00 4d 21 fc 4c 89 e0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 e7 e8 06 11 cc f7 4d 23 3c 24 4c 89 ff 4c
RSP: 0018:ffffc90004147720 EFLAGS: 00000a02
RAX: 1ffff11004f2f380 RBX: ffff888027979c00 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffffff97058440
RBP: ffffc900041478f0 R08: 0000000000000004 R09: 0000000000000003
R10: fffffbfff2e0b088 R11: 1ffffffff2e0b088 R12: ffff888027979c00
R13: 00007fec1bbecfff R14: 0000000000000001 R15: ffffffffffffff00
 validate_mm_mt+0xcd/0x420 mm/mmap.c:295
 validate_mm+0xcc/0x2b0 mm/mmap.c:332
 remove_mt mm/mmap.c:2322 [inline]
 do_mas_align_munmap+0xf98/0x1220 mm/mmap.c:2595
 do_mas_munmap+0x240/0x2b0 mm/mmap.c:2650
 __vm_munmap+0x18d/0x290 mm/mmap.c:2936
 __do_sys_munmap mm/mmap.c:2961 [inline]
 __se_sys_munmap mm/mmap.c:2958 [inline]
 __x64_sys_munmap+0x5c/0x70 mm/mmap.c:2958
 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: 0033:0x7fec1bb1e097
RSP: 002b:00007fffcc99cd78 EFLAGS: 00000246 ORIG_RAX: 000000000000000b
RAX: ffffffffffffffda RBX: 000055a578e76a90 RCX: 00007fec1bb1e097
RDX: 000055a578e65358 RSI: 0000000000000200 RDI: 00007fec1c18e000
RBP: 0000000000000001 R08: 000055a578e6dee0 R09: 000055a578e6a010
R10: 0000000000000000 R11: 0000000000000246 R12: 000055a578e680b0
R13: 00007fec1c2b839c R14: 0000000000000200 R15: 0000000000000009
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10535 jiffies! g38653 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=21076
rcu: rcu_preempt kthread starved for 10541 jiffies! g38653 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27200 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
CPU: 1 PID: 1277 Comm: aoe_tx0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:29 [inline]
RIP: 0010:arch_atomic_fetch_add_unless include/linux/atomic/atomic-arch-fallback.h:1242 [inline]
RIP: 0010:arch_atomic_add_unless include/linux/atomic/atomic-arch-fallback.h:1267 [inline]
RIP: 0010:atomic_add_unless include/linux/atomic/atomic-instrumented.h:608 [inline]
RIP: 0010:uart_port_ref drivers/tty/serial/serial_core.c:64 [inline]
RIP: 0010:uart_write_room+0x5c/0x2c0 drivers/tty/serial/serial_core.c:613
Code: 89 df e8 d7 a7 5b fd 48 8b 1b 4c 8d b3 b0 03 00 00 4c 89 f7 be 04 00 00 00 e8 60 a9 5b fd 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 <84> c0 0f 85 b1 01 00 00 45 8b 3e 31 ff 44 89 fe e8 bf 89 0b fd 45
RSP: 0018:ffffc90005667998 EFLAGS: 00000a06
RAX: 0000000000000000 RBX: ffff888024040c30 RCX: ffffffff84754a10
RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffff888024040fe0
RBP: 0000000000000020 R08: dffffc0000000000 R09: ffffed10048081fd
R10: ffffed10048081fd R11: 1ffff110048081fc R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff888024040fe0 R15: ffff888057e09000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fec1c16d000 CR3: 00000000183d7000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 handle_tx+0x164/0x600 drivers/net/caif/caif_serial.c:226
 __netdev_start_xmit include/linux/netdevice.h:4896 [inline]
 netdev_start_xmit include/linux/netdevice.h:4910 [inline]
 xmit_one net/core/dev.c:3670 [inline]
 dev_hard_start_xmit+0x262/0x870 net/core/dev.c:3686
 __dev_queue_xmit+0x1bf1/0x3760 net/core/dev.c:4346
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 tx+0x67/0x170 drivers/block/aoe/aoenet.c:63
 kthread+0x1c6/0x3b0 drivers/block/aoe/aoecmd.c:1241
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>