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[2003:d8:2f2b:d900:2d94:8433:b532:3418]) by smtp.gmail.com with ESMTPSA id o10-20020a5d684a000000b0031758e7ba6dsm13532656wrw.40.2023.08.14.00.55.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Aug 2023 00:55:04 -0700 (PDT) Message-ID: <00dd353b-e5aa-69fb-6b52-cb59028ea90a@redhat.com> Date: Mon, 14 Aug 2023 09:55:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Content-Language: en-US To: Mateusz Guzik , linux-kernel@vger.kernel.org Cc: torvalds@linux-foundation.org, brauner@kernel.org, ebiederm@xmission.com, akpm@linux-foundation.org, linux-mm@kvack.org, koct9i@gmail.com, oleg@redhat.com, dave@stgolabs.net References: <20230813123333.1705833-1-mjguzik@gmail.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] kernel/fork: stop playing lockless games for exe_file replacement In-Reply-To: <20230813123333.1705833-1-mjguzik@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13.08.23 14:33, Mateusz Guzik wrote: > xchg originated in 6e399cd144d8 ("prctl: avoid using mmap_sem for > exe_file serialization"). While the commit message does not explain > *why* the change, clearly the intent was to use mmap_sem less in this > codepath. I found the original submission [1] which ultimately claims it > cleans things up. More details are apparently in v1 of that patch: https://lore.kernel.org/lkml/1424979417.10344.14.camel@stgolabs.net/ Regarding your patch: adding more mmap_write_lock() where avoidable, I'm not so sure. Your patch doesn't look (to me) like it is removing a lot of complexity. -- Cheers, David / dhildenb