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b=yPITqYApklWsg7GXdNRWSYrT42/vqoyceqxpRWdnMClXlwluh0UGWLrcLU+kR3sB7 rIlPtIibUq0cN4oBa30v+x2sfpyNUz4Dfy4c6m8LvXLq7O9M4cySB14QVonTSqiofo S1K/PMv7uS3ObPup2jZFrYazE+QhrFAs5AIBnReE= Date: Fri, 1 Aug 2025 20:53:23 -0700 From: Andrew Morton To: Waiman Long Cc: Gu Bowen , Catalin Marinas , stable@vger.kernel.org, linux-mm@kvack.org, Lu Jialin , Breno Leitao Subject: Re: [PATCH] mm: Fix possible deadlock in console_trylock_spinning Message-Id: <20250801205323.70c2fabe5f64d2fb7c64fd94@linux-foundation.org> In-Reply-To: <5ca375cd-4a20-4807-b897-68b289626550@redhat.com> References: <20250730094914.566582-1-gubowen5@huawei.com> <20250801153303.cee42dcfc94c63fb5026bba0@linux-foundation.org> <5ca375cd-4a20-4807-b897-68b289626550@redhat.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: m3ccibeps9kdjghah5u7qihg7n8t5jzb X-Rspamd-Queue-Id: 58CAF100002 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1754106806-478999 X-HE-Meta: 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 G3zM1Xxx ox2EfyOxdDJRWDAuVSL9t0vLuvRJYQDZ8eeotRo6PIoNWkA95DE2Rjug26IhftA6dtoY31xg/mt+YiMv8FINYMbAJfL6ia5yohDbjq/xBceumpa/SmAzZ9jE+s1G2tksQU6FkTmQ1yl5g9Zc1NvYsD/GaiPhW7YvL82j2nYM+b6W4hwbg6aEmQO6IECEBxiNAIYfWCoYbFqx785dBFKwhURZWl6E+upEhYWPaWVqRFADeHNmxkf/edHSmJa3tqf+7F6CcNfnRiPGBm/pym38x9FADpulIs/ElUQn5i6RhQOJZ+shHytyw/GNnRgXQSjh1cuEv7Yxn6vaNYfHZJrFOarEgeUeYZnFpWuNDeIUBYTCMBwNMgkriCpSY0cxiGsQAvba2Dxyde/5BBoA= 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 Fri, 1 Aug 2025 23:09:31 -0400 Waiman Long wrote: > > Thanks. > > > > There have been a few kmemleak locking fixes lately. > > > > I believe this fix is independent from the previous ones: > > > > https://lkml.kernel.org/r/20250731-kmemleak_lock-v1-1-728fd470198f@debian.org > > https://lkml.kernel.org/r/20250728190248.605750-1-longman@redhat.com > > > > But can people please check? > > I believe that __printk_safe_enter()/_printk_safe_exit() are for printk > internal use only. The proper API to use should be > printk_deferred_enter()/printk_deferred_exit() if we want to deferred > the printing. Since kmemleak_lock will have been acquired with irq > disabled, it meets the condition that printk_deferred_*() APIs can be used. Gotcha, thanks. kmemleak;c:__lookup_object() has a lot of callers. I hope you're correct that all have local irqs enabled, but I'll ask Gu to verify that then please send along a new patch which uses printk_deferred_enter()?