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Date:   Mon, 23 Nov 2020 11:52:35 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Xu Qiang <xuqiang36@huawei.com>
Cc:     <keescook@chromium.org>, <mingo@kernel.org>,
        <peterz@infradead.org>, <mcgrof@kernel.org>, <huyue2@yulong.com>,
        <yangtiezhu@loongson.cn>, <will@kernel.org>, <aquini@redhat.com>,
        <gpiccoli@canonical.com>, <aik@ozlabs.ru>,
        <linux-kernel@vger.kernel.org>, <rui.xiang@huawei.com>
Subject: Re: [PATCH -next] panic: complete the flush of the hard deadlock
 log messages to the serial port
Message-Id: <20201123115235.74aab2449ac5cf27f10a4cfd@linux-foundation.org>
In-Reply-To: <20201123131359.34600-1-xuqiang36@huawei.com>
References: <20201123131359.34600-1-xuqiang36@huawei.com>
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On Mon, 23 Nov 2020 13:13:59 +0000 Xu Qiang <xuqiang36@huawei.com> wrote:

> when hardlockup_all_cpu_backtrace is on, and there are
> a large number of cores in the system, it takes
> a long time to output the hard deadlock logs of all cores
> to the serial port. When the console_flush_on_panic function
> in panic is executed, console_locked is still held.
> As a result, garbled characters are displayed in the serial port log.
> 
> To solve this problem, wait for a maximum of 10s for the serial port
> to be released before console_flush_on_panic.

Wouldn't it be better to wait until all the printing of all those
backtraces has completed?