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Thu, 12 Jun 2025 05:21:56 -0700 (PDT) Message-ID: <9275145b-3066-41e5-a971-eba219ef0d3c@gmail.com> Date: Thu, 12 Jun 2025 20:21:51 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] md/raid1: Fix stack memory use after return in raid1_reshape To: Yu Kuai , Song Liu Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, "yukuai (C)" References: <20250611090203.271488-1-wangjinchao600@gmail.com> <5143c5c3-3a77-919f-0d38-8adb0e8923e9@huaweicloud.com> <06935480-a959-4e3f-8e41-286d7f54754a@gmail.com> <9c7d5e66-4f5f-b984-c291-f19c3d568b85@huaweicloud.com> <938b0969-cace-4998-8e4a-88d445c220b1@gmail.com> <8a876d8f-b8d1-46c0-d969-cbabb544eb03@huaweicloud.com> <726fe46d-afd5-4247-86a0-14d7f0eeb3b3@gmail.com> Content-Language: en-US From: Wang Jinchao In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2025/6/12 19:58, Yu Kuai wrote: > Hi, > > 在 2025/06/12 19:46, Wang Jinchao 写道: >> On 2025/6/12 19:23, Yu Kuai wrote: >>> Hi, >>> >>> 在 2025/06/12 17:55, Wang Jinchao 写道: >>>> Now that we have the same information, I prefer patch-v1 before >>>> refactoring raid1_reshape, >>>> because it’s really simple (only one line) and clearer to show the >>>> backup and restore logic. >>>> Another reason is that v2 freezes the RAID longer than v1. >>>> Would you like me to provide a v3 patch combining the v2 explanation >>>> with the v1 diff? >>>> Thanks for your reviewing. >>> >>> I don't have preference here, feel free to do this. >>> >>> BTW, I feel raid1_reshape can be better coding with following： >>> >>> - covert r1bio_pool to use mempool_create_kmalloc_pool(use create >>> instead of init to get rid of the werid assigment); >> mempool_create_kmalloc_pool also calls init_waitqueue_head(&pool- >> >wait) internally, just like mempool_init. > > Please notice that creat will allocate memory for mempool, the list is > no longer a stack value, the field bio_pool inside conf should also > covert to a pointer. > >> So the issue only exists if newpool is allocated on the stack. >>> - no need to reallocate pool_info; >>> - convert raid1_info to use krealloc; >> I think reallocating pool_info is only for backup and restore, similar >> to newpool. > > You can just change the old value directly, after everything is ready, > with the first mempool change, pool_info is not needed for bio_pool. >>> >>> Welcome if you are willing to, otherwise I'll find myself sometime. >> I'm a newcomer to RAID and can't quite catch up with it right now. >> Maybe I can refactor it later, and I look forward to your guidance. >>> > > No hurry, take you time :) 👍 You're right — now I understand the whole. I'm willing to try refactoring raid1_reshape later. > > Thanks, > Kuai >