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([2a02:3033:283:b9b7:bec2:3dce:f757:ce06]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49ccea6b814sm176057695e9.0.2026.08.31.06.27.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Aug 2026 06:27:09 -0700 (PDT) Message-ID: Date: Mon, 31 Aug 2026 15:27:07 +0200 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 1/4] USB: usbfs: replace __get_free_page() with kmalloc() To: "Mike Rapoport (Microsoft)" , Chas Williams <3chas3@gmail.com>, Duncan Sands , Greg Kroah-Hartman , Johan Hovold Cc: Andrew Morton , David Hildenbrand , Matthew Wilcox , Vlastimil Babka , accessrunner-general@lists.sourceforge.net, linux-atm-general@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-usb@vger.kernel.org, netdev@vger.kernel.org References: <20260830-usb-v1-0-aa349c302246@kernel.org> <20260830-usb-v1-1-aa349c302246@kernel.org> Content-Language: en-US From: Oliver Neukum In-Reply-To: <20260830-usb-v1-1-aa349c302246@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 30.08.26 10:10, Mike Rapoport (Microsoft) wrote: > do_proc_control() allocates a temporary buffer for the data stage of a > control transfer issued from userspace. > > This buffer can be allocated with kmalloc() as there's nothing special > about it to go directly to the page allocator. You are breaking the calculation. A page has a size of exactly PAGE_SIZE. A kmalloced object of PAGE_SIZE is larger. That is a bad idea. Regards Oliver