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Thu, 7 Aug 2025 11:22:10 +0800 Message-ID: <6e278baf-c6e4-49ee-9880-6c15a2c1b996@huawei.com> Date: Thu, 7 Aug 2025 11:22:09 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: Fix possible deadlock in console_trylock_spinning To: John Ogness , Waiman Long , Andrew Morton CC: Catalin Marinas , , , Lu Jialin , Breno Leitao References: <20250730094914.566582-1-gubowen5@huawei.com> <20250801153303.cee42dcfc94c63fb5026bba0@linux-foundation.org> <5ca375cd-4a20-4807-b897-68b289626550@redhat.com> <84h5yko44i.fsf@jogness.linutronix.de> Content-Language: en-US From: Gu Bowen In-Reply-To: <84h5yko44i.fsf@jogness.linutronix.de> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.111.31] X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemh100007.china.huawei.com (7.202.181.92) X-Rspamd-Queue-Id: F20BC140004 X-Stat-Signature: f3e4ox51b1ajps1n4peig9rja35cfgky X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1754536934-834531 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/6/2025 11:34 PM, John Ogness wrote: > > printk no longer works like this. There are no special per-CPU > buffers. As correctly pointed out by Longman, the proper interface is > printk_deferred_enter()/printk_deferred_exit(). > > With the deferred interface, the printk message is still immediately > stored in the printk ringbuffer (which is lockless) and only the console > printing itself is deferred. > Hi, I agree that printk_deferred_enter()/printk_deferred_exit() is a better interface, but I noticed that in stable-5.10, the printk safety mode still uses a per-CPU buffer to store messages through the printk_safe_log_store function. Additionally, the mainline version has already refactored printk, so this issue no longer exists.