syzbot

sched: RT throttling activated
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=8537, q=65 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294962619-4294952117), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g8537 f0x2 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:27376 pid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
 rcu_gp_fqs_loop+0x302/0x1560 kernel/rcu/tree.c:1667
 rcu_gp_kthread+0x99/0x380 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:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5836 Comm: vhost-5834 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:26 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:89 [inline]
RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:107 [inline]
RIP: 0010:lock_is_held_type+0x65/0x190 kernel/locking/lockdep.c:5821
Code: 0f 85 f4 00 00 00 65 48 8b 1d 47 75 94 75 83 bb dc 0a 00 00 00 0f 85 df 00 00 00 41 89 f7 49 89 fe 48 c7 04 24 00 00 00 00 9c <8f> 04 24 4c 8b 2c 24 fa 48 c7 c7 c0 c9 aa 8a e8 47 13 00 00 65 ff
RSP: 0018:ffffc900046ef1f0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888024998000 RCX: ffff888024998000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffff8880236627a0
RBP: 00000000ffffffff R08: ffff888024998000 R09: 0000000000000003
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000000
R13: 00001fffffffefff R14: ffff8880236627a0 R15: 00000000ffffffff
FS:  0000555590f3b380(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000002 CR3: 000000007b57d000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 lock_is_held include/linux/lockdep.h:288 [inline]
 mt_locked lib/maple_tree.c:-1 [inline]
 mt_slot lib/maple_tree.c:812 [inline]
 mtree_range_walk+0x4d2/0x7c0 lib/maple_tree.c:2818
 mas_state_walk lib/maple_tree.c:3712 [inline]
 mt_find+0x22b/0x5b0 lib/maple_tree.c:6546
 find_vma+0x12e/0x1b0 mm/mmap.c:1888
 gup_vma_lookup mm/gup.c:1017 [inline]
 __get_user_pages+0x37a/0x1470 mm/gup.c:1135
 __get_user_pages_locked mm/gup.c:1431 [inline]
 __gup_longterm_locked+0x2247/0x2b80 mm/gup.c:2127
 internal_get_user_pages_fast+0x217f/0x2730 mm/gup.c:3227
 set_bit_to_user drivers/vhost/vhost.c:2194 [inline]
 log_write+0xc4/0x350 drivers/vhost/vhost.c:2220
 vhost_update_used_flags+0x1c3/0x290 drivers/vhost/vhost.c:2339
 vhost_enable_notify+0xb7/0x810 drivers/vhost/vhost.c:2899
 vhost_vsock_handle_tx_kick+0x2d6/0xdb0 drivers/vhost/vsock.c:504
 vhost_run_work_list+0x13d/0x1b0 drivers/vhost/vhost.c:419
 vhost_task_fn+0x25a/0x3c0 kernel/vhost_task.c:49
 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>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.044 msecs