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Message-ID: <6dab6e564e43c952f63f83ef868da6ed829fc1a8.camel@mediatek.com>
Subject: BUG: list_add corruption while doing migrate_swap -> balance_push
From:   Kuyo Chang <kuyo.chang@mediatek.com>
To:     <mingo@redhat.com>, <peterz@infradead.org>,
        <juri.lelli@redhat.com>, <vincent.guittot@linaro.org>,
        <dietmar.eggemann@arm.com>, <rostedt@goodmis.org>,
        <bsegall@google.com>, <mgorman@suse.de>, <bristot@redhat.com>
CC:     <linux-kernel@vger.kernel.org>, <wsd_upstream@mediatek.com>,
        <linux-mediatek@lists.infradead.org>, <jing-ting.wu@mediatek.com>,
        <yt.chang@mediatek.com>, <jonathan.jmchen@mediatek.com>
Date:   Tue, 6 Sep 2022 20:54:58 +0800
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Hi,

[Syndrome]
A list_add corruption error at kernel-5.15, the log shows.
list_add corruption. prev->next should be next (ffffff81a6f08ba0), but
was 0000000000000000. (prev=ffffff81a6f05930).

The call trace as below:
ipanic_die
notify_die
die
bug_handler
brk_handler
do_debug_exception
el1_dbg
el1h_64_sync_handler
el1h_64_sync
__list_add_valid
cpu_stop_queue_work
stop_one_cpu_nowait
balance_push
__schedule
schedule
do_sched_yield
__arm64_sys_sched_yield
invoke_syscall
el0_svc_common
do_el0_svc
el0_svc
el0t_64_sync_handler
el0t_64_sync

[Analysis]
By memory dump and analyzing the stopper->works list, the error code
flow as following:

migrate_swap 
->stop_two_cpus
	->cpu_stop_queue_two_works
		->__cpu_stop_queue_work (add work->list to stopper-
>works respectively)	
			->list_add_tail(&work->list, &stopper->works);
	->wake_up_q(&wakeq);	
->wait_for_completion(&done.completion);
->wait_for_common
->schedule_timeout
->schedule

At this point, the cpu hotplug trigged,
It registers balance_callback by below flow:
cpu_down(cpuid)
->_cpu_down
->cpuhp_set_state()
->set_cpu_dying(cpuid, true)
->sched_cpu_deactivate
->balance_push_set(cpuid, true)
	->rq->balance_callback = &balance_push_callback;


Finally, 
->__schedule
->__balance_callbacks
->do_balance_callbacks(rq, __splice_balance_callbacks(rq, false));
->balance_push
->stop_one_cpu_nowait
	*work_buf = (struct cpu_stop_work){ .fn = fn, .arg = arg,
.caller = _RET_IP_, };
At this point the list_head *next, *prev is initial to NULL!!
->cpu_stop_queue_work
->__list_add_valid

So it will hit this error 
if (CHECK_DATA_CORRUPTION(next->prev != prev,
	"list_add corruption. next->prev should be prev (%px), but was
%px. (next=%px).\n",
	prev, next->prev, next)

Do you have any suggestion for this issue?
Thank you.