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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 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 X-Rspam-User: X-Stat-Signature: af59pcgdisfm3c8droi3qnkuigxdfuwj X-Rspamd-Queue-Id: 44221180011 X-Rspamd-Server: rspam06 X-HE-Tag: 1788182831-456879 X-HE-Meta: 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 CKUjoS+S 0kcFmlTJn4Ofq+rSSYZQNPl6paDJdX/K3Pi63Oi26pA81WLRHS0J7Hzy3zCBUfd66Kt6luP9/jcKvpeJofWoQ13RLvquNUEhFPfRqwbGzLzJeVCpJQVXZ4Llfy17ld/pDCyWq+eGrexLuRCp7rFuVsinHkMP3/LftkisVfzQ0WXEzbzlgwA74/HrINT7YHzHuleEvkonpg4A8YQ55LgWB7OR3wSMvuBFdHvdP6mffmrtElLWLPSZqB+z6Ygdnzxh2SSp86eXVZ1f2ovhYs23ER8+Be0KQWZJ+R4D9lNNKdmRj5sA9KOr914qKIKD6Qz8lvfB2f+EpbeBRHE69JLjpaip5twVBKqFKLcxZx3WuFBrQjj8SbVeKNuoapi2nmwqLWA9Ug2XjLC1Tgl0FkjRMOHXBHsVnp/Z3MTfj/Q03aNz0X7hHtUfy2f3iWA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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