syzbot

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INFO: rcu_preempt detected stalls on CPUs/tasks:
	Tasks blocked on level-0 rcu_node (CPUs 0-1): P9971
	(detected by 0, t=10502 jiffies, g=71585, c=71584, q=357)
kworker/u4:0    R  running task    22832  9971      2 0x80000000
Workqueue: events_unbound call_usermodehelper_exec_work
Call Trace:
 preempt_schedule_common+0x4f/0xd0 kernel/sched/core.c:3579
 ___preempt_schedule+0x16/0x18
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x3b/0x40 kernel/locking/spinlock.c:184
 spin_unlock include/linux/spinlock.h:357 [inline]
 task_unlock include/linux/sched/task.h:136 [inline]
 dump_tasks mm/oom_kill.c:403 [inline]
 dump_header+0x7bb/0x848 mm/oom_kill.c:428
 oom_kill_process.cold+0x10/0xde6 mm/oom_kill.c:861
 out_of_memory mm/oom_kill.c:1084 [inline]
 out_of_memory+0x2d2/0xab0 mm/oom_kill.c:1023
 __alloc_pages_may_oom mm/page_alloc.c:3415 [inline]
 __alloc_pages_slowpath mm/page_alloc.c:4112 [inline]
 __alloc_pages_nodemask+0x1988/0x2370 mm/page_alloc.c:4277
 __alloc_pages include/linux/gfp.h:484 [inline]
 __alloc_pages_node include/linux/gfp.h:497 [inline]
 alloc_pages_node include/linux/gfp.h:511 [inline]
 alloc_thread_stack_node kernel/fork.c:243 [inline]
 dup_task_struct kernel/fork.c:529 [inline]
 copy_process.part.0+0x2c9/0x66c0 kernel/fork.c:1729
 copy_process kernel/fork.c:1679 [inline]
 _do_fork+0x197/0xce0 kernel/fork.c:2220
 kernel_thread+0x2f/0x40 kernel/fork.c:2284
 call_usermodehelper_exec_sync kernel/umh.c:123 [inline]
 call_usermodehelper_exec_work+0xa7/0x230 kernel/umh.c:175
 process_one_work+0x7f1/0x1580 kernel/workqueue.c:2134
 worker_thread+0xdd/0xdf0 kernel/workqueue.c:2271
 kthread+0x31f/0x430 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404
kworker/u4:0    R  running task    22832  9971      2 0x80000000
Workqueue: events_unbound call_usermodehelper_exec_work
Call Trace:
 preempt_schedule_common+0x4f/0xd0 kernel/sched/core.c:3579
 ___preempt_schedule+0x16/0x18
 __raw_spin_unlock include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock+0x3b/0x40 kernel/locking/spinlock.c:184
 spin_unlock include/linux/spinlock.h:357 [inline]
 task_unlock include/linux/sched/task.h:136 [inline]
 dump_tasks mm/oom_kill.c:403 [inline]
 dump_header+0x7bb/0x848 mm/oom_kill.c:428
 oom_kill_process.cold+0x10/0xde6 mm/oom_kill.c:861
 out_of_memory mm/oom_kill.c:1084 [inline]
 out_of_memory+0x2d2/0xab0 mm/oom_kill.c:1023
 __alloc_pages_may_oom mm/page_alloc.c:3415 [inline]
 __alloc_pages_slowpath mm/page_alloc.c:4112 [inline]
 __alloc_pages_nodemask+0x1988/0x2370 mm/page_alloc.c:4277
 __alloc_pages include/linux/gfp.h:484 [inline]
 __alloc_pages_node include/linux/gfp.h:497 [inline]
 alloc_pages_node include/linux/gfp.h:511 [inline]
 alloc_thread_stack_node kernel/fork.c:243 [inline]
 dup_task_struct kernel/fork.c:529 [inline]
 copy_process.part.0+0x2c9/0x66c0 kernel/fork.c:1729
 copy_process kernel/fork.c:1679 [inline]
 _do_fork+0x197/0xce0 kernel/fork.c:2220
 kernel_thread+0x2f/0x40 kernel/fork.c:2284
 call_usermodehelper_exec_sync kernel/umh.c:123 [inline]
 call_usermodehelper_exec_work+0xa7/0x230 kernel/umh.c:175
 process_one_work+0x7f1/0x1580 kernel/workqueue.c:2134
 worker_thread+0xdd/0xdf0 kernel/workqueue.c:2271
 kthread+0x31f/0x430 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404
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