Re: [RFC] workqueue: allow system workqueue be used in memory reclaim

From: kernel test robot
Date: Thu Nov 16 2023 - 02:39:55 EST



Hello,

kernel test robot noticed "WARNING:possible_circular_locking_dependency_detected" on:

commit: c8c183493c1dcc874a9d903cb6ba685c98f6c12a ("[RFC] workqueue: allow system workqueue be used in memory reclaim")
url: https://github.com/intel-lab-lkp/linux/commits/Junxiao-Bi/workqueue-allow-system-workqueue-be-used-in-memory-reclaim/20231108-093107
base: https://git.kernel.org/cgit/linux/kernel/git/tj/wq.git for-next
patch link: https://lore.kernel.org/all/20231108012821.56104-1-junxiao.bi@xxxxxxxxxx/
patch subject: [RFC] workqueue: allow system workqueue be used in memory reclaim

in testcase: boot

compiler: gcc-12
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-lkp/202311161556.59af3ec9-oliver.sang@xxxxxxxxx


[ 6.524239][ T9] WARNING: possible circular locking dependency detected
[ 6.524787][ T9] 6.6.0-rc6-00056-gc8c183493c1d #1 Not tainted
[ 6.525271][ T9] ------------------------------------------------------
[ 6.525606][ T9] kworker/0:1/9 is trying to acquire lock:
[ 6.525606][ T9] ffffffff88f6f480 (cpu_hotplug_lock){++++}-{0:0}, at: vmstat_shepherd (include/linux/find.h:63 mm/vmstat.c:2025)
[ 6.525606][ T9]
[ 6.525606][ T9] but task is already holding lock:
[ 6.525606][ T9] ffff888110aa7d88 ((shepherd).work){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:2606)
[ 6.525606][ T9]
[ 6.525606][ T9] which lock already depends on the new lock.
[ 6.525606][ T9]
[ 6.525606][ T9] the existing dependency chain (in reverse order) is:
[ 6.525606][ T9]
[ 6.525606][ T9] -> #2 ((shepherd).work){+.+.}-{0:0}:
[ 6.525606][ T9] __lock_acquire (kernel/locking/lockdep.c:5136)
[ 6.525606][ T9] lock_acquire (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5755)
[ 6.525606][ T9] process_one_work (arch/x86/include/asm/atomic.h:23 include/linux/atomic/atomic-arch-fallback.h:444 include/linux/jump_label.h:260 include/linux/jump_label.h:270 include/trace/events/workqueue.h:82 kernel/workqueue.c:2629)
[ 6.525606][ T9] worker_thread (kernel/workqueue.c:2697 kernel/workqueue.c:2784)
[ 6.525606][ T9] kthread (kernel/kthread.c:388)
[ 6.525606][ T9] ret_from_fork (arch/x86/kernel/process.c:153)
[ 6.525606][ T9] ret_from_fork_asm (arch/x86/entry/entry_64.S:312)
[ 6.525606][ T9]
[ 6.525606][ T9] -> #1 ((wq_completion)events){+.+.}-{0:0}:
[ 6.525606][ T9] __lock_acquire (kernel/locking/lockdep.c:5136)
[ 6.525606][ T9] lock_acquire (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5755)
[ 6.525606][ T9] start_flush_work (kernel/workqueue.c:3383)
[ 6.525606][ T9] __flush_work (kernel/workqueue.c:3406)
[ 6.525606][ T9] schedule_on_each_cpu (kernel/workqueue.c:3668 (discriminator 3))
[ 6.525606][ T9] rcu_tasks_one_gp (kernel/rcu/rcu.h:109 kernel/rcu/tasks.h:587)
[ 6.525606][ T9] rcu_tasks_kthread (kernel/rcu/tasks.h:625 (discriminator 1))
[ 6.525606][ T9] kthread (kernel/kthread.c:388)
[ 6.525606][ T9] ret_from_fork (arch/x86/kernel/process.c:153)
[ 6.525606][ T9] ret_from_fork_asm (arch/x86/entry/entry_64.S:312)
[ 6.525606][ T9]
[ 6.525606][ T9] -> #0 (cpu_hotplug_lock){++++}-{0:0}:
[ 6.525606][ T9] check_prev_add (kernel/locking/lockdep.c:3135)
[ 6.525606][ T9] validate_chain (kernel/locking/lockdep.c:3254 kernel/locking/lockdep.c:3868)
[ 6.525606][ T9] __lock_acquire (kernel/locking/lockdep.c:5136)
[ 6.525606][ T9] lock_acquire (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5755)
[ 6.525606][ T9] cpus_read_lock (include/linux/percpu-rwsem.h:53 kernel/cpu.c:489)
[ 6.525606][ T9] vmstat_shepherd (include/linux/find.h:63 mm/vmstat.c:2025)
[ 6.525606][ T9] process_one_work (kernel/workqueue.c:2635)
[ 6.525606][ T9] worker_thread (kernel/workqueue.c:2697 kernel/workqueue.c:2784)
[ 6.525606][ T9] kthread (kernel/kthread.c:388)
[ 6.525606][ T9] ret_from_fork (arch/x86/kernel/process.c:153)
[ 6.525606][ T9] ret_from_fork_asm (arch/x86/entry/entry_64.S:312)
[ 6.525606][ T9]
[ 6.525606][ T9] other info that might help us debug this:
[ 6.525606][ T9]
[ 6.525606][ T9] Chain exists of:
[ 6.525606][ T9] cpu_hotplug_lock --> (wq_completion)events --> (shepherd).work
[ 6.525606][ T9]
[ 6.525606][ T9] Possible unsafe locking scenario:
[ 6.525606][ T9]
[ 6.525606][ T9] CPU0 CPU1
[ 6.525606][ T9] ---- ----
[ 6.525606][ T9] lock((shepherd).work);
[ 6.525606][ T9] lock((wq_completion)events);
[ 6.525606][ T9] lock((shepherd).work);
[ 6.525606][ T9] rlock(cpu_hotplug_lock);
[ 6.525606][ T9]
[ 6.525606][ T9] *** DEADLOCK ***
[ 6.525606][ T9]
[ 6.525606][ T9] 2 locks held by kworker/0:1/9:
[ 6.525606][ T9] #0: ffff88810007cd48 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:2603)
[ 6.525606][ T9] #1: ffff888110aa7d88 ((shepherd).work){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:2606)
[ 6.525606][ T9]
[ 6.525606][ T9] stack backtrace:
[ 6.525606][ T9] CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.6.0-rc6-00056-gc8c183493c1d #1
[ 6.525606][ T9] Workqueue: events vmstat_shepherd
[ 6.525606][ T9] Call Trace:
[ 6.525606][ T9] <TASK>
[ 6.525606][ T9] dump_stack_lvl (lib/dump_stack.c:107)
[ 6.525606][ T9] check_noncircular (kernel/locking/lockdep.c:2187)
[ 6.525606][ T9] ? print_circular_bug (kernel/locking/lockdep.c:2163)
[ 6.525606][ T9] ? stack_trace_save (kernel/stacktrace.c:123)
[ 6.525606][ T9] ? stack_trace_snprint (kernel/stacktrace.c:114)
[ 6.525606][ T9] check_prev_add (kernel/locking/lockdep.c:3135)
[ 6.525606][ T9] validate_chain (kernel/locking/lockdep.c:3254 kernel/locking/lockdep.c:3868)
[ 6.525606][ T9] ? check_prev_add (kernel/locking/lockdep.c:3824)
[ 6.525606][ T9] ? hlock_class (arch/x86/include/asm/bitops.h:228 arch/x86/include/asm/bitops.h:240 include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228)
[ 6.525606][ T9] ? mark_lock (kernel/locking/lockdep.c:4655 (discriminator 3))
[ 6.525606][ T9] __lock_acquire (kernel/locking/lockdep.c:5136)
[ 6.525606][ T9] lock_acquire (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5755)
[ 6.525606][ T9] ? vmstat_shepherd (include/linux/find.h:63 mm/vmstat.c:2025)
[ 6.525606][ T9] ? lock_sync (kernel/locking/lockdep.c:5721)
[ 6.525606][ T9] ? debug_object_active_state (lib/debugobjects.c:772)
[ 6.525606][ T9] ? __cant_migrate (kernel/sched/core.c:10142)
[ 6.525606][ T9] cpus_read_lock (include/linux/percpu-rwsem.h:53 kernel/cpu.c:489)
[ 6.525606][ T9] ? vmstat_shepherd (include/linux/find.h:63 mm/vmstat.c:2025)
[ 6.525606][ T9] vmstat_shepherd (include/linux/find.h:63 mm/vmstat.c:2025)
[ 6.525606][ T9] process_one_work (kernel/workqueue.c:2635)
[ 6.525606][ T9] ? worker_thread (kernel/workqueue.c:2740)
[ 6.525606][ T9] ? show_pwq (kernel/workqueue.c:2539)
[ 6.525606][ T9] ? assign_work (kernel/workqueue.c:1096)
[ 6.525606][ T9] worker_thread (kernel/workqueue.c:2697 kernel/workqueue.c:2784)
[ 6.525606][ T9] ? __kthread_parkme (kernel/kthread.c:293 (discriminator 3))
[ 6.525606][ T9] ? schedule (arch/x86/include/asm/bitops.h:207 (discriminator 1) arch/x86/include/asm/bitops.h:239 (discriminator 1) include/linux/thread_info.h:184 (discriminator 1) include/linux/sched.h:2255 (discriminator 1) kernel/sched/core.c:6773 (discriminator 1))
[ 6.525606][ T9] ? process_one_work (kernel/workqueue.c:2730)
[ 6.525606][ T9] kthread (kernel/kthread.c:388)
[ 6.525606][ T9] ? _raw_spin_unlock_irq (arch/x86/include/asm/irqflags.h:42 arch/x86/include/asm/irqflags.h:77 include/linux/spinlock_api_smp.h:159 kernel/locking/spinlock.c:202)


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20231116/202311161556.59af3ec9-oliver.sang@xxxxxxxxx



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0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki