From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9FB6EB64DB for ; Thu, 22 Jun 2023 10:00:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229985AbjFVKAH (ORCPT ); Thu, 22 Jun 2023 06:00:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230125AbjFVKAG (ORCPT ); Thu, 22 Jun 2023 06:00:06 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D27B1A4; Thu, 22 Jun 2023 03:00:04 -0700 (PDT) Received: from [192.168.10.55] (unknown [182.179.162.32]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: usama.anjum) by madras.collabora.co.uk (Postfix) with ESMTPSA id ACB56660700E; Thu, 22 Jun 2023 10:59:52 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1687428003; bh=j6EIKy4cSoieiiC75xDAROKxOVZOc1C1Q3ERjaD2rrg=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=kRefeMfElCB0LrRwAPYztcZVCqNLKlAY97v3Q/+gSbt8FQGxVOiOkBAPJfhVBGx6v mmAZmocJdVTX/rjNz+1F8eGoJUORk1IdrLsGp3Z+dcEEKCCY/1POO+SLkGxgtPyYea iClcyMr22ugS09ZVw0JKZ6pJdESY0iN07Ru7l6Qh33JovoYECG8HFySgIz9RZ5dsJu m9TQvgRJTypc6GSUtvLPgvhCEmkeWHTN2YsuBmkHOGCG5voJ/WyscBGvjpKtQx2QQX 5Af7LXdLzf2Ldq09coY0AWmqPVxnnPRgYHszu5hdJrN502Q6JPV8YwM4auwxYskvqc pr/YXHD+luiDA== Message-ID: <76725a75-b17d-8a88-8d41-15c8daafe7e4@collabora.com> Date: Thu, 22 Jun 2023 14:59:48 +0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Cc: Muhammad Usama Anjum , Andrei Vagin , Peter Xu , David Hildenbrand , Andrew Morton , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Mike Rapoport , Nadav Amit , Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: Re: [PATCH v19 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs To: =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= References: <20230615141144.665148-1-usama.anjum@collabora.com> <20230615141144.665148-3-usama.anjum@collabora.com> <1c1beeda-ceed-fdab-bbf5-1881e0a8b102@collabora.com> Content-Language: en-US From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On 6/21/23 6:29 PM, Michał Mirosław wrote: > On Wed, 21 Jun 2023 at 08:35, Muhammad Usama Anjum > wrote: >> On 6/20/23 11:03 PM, Andrei Vagin wrote: >> ... >>>> +struct pagemap_scan_private { >>>> + struct page_region *vec_buf, cur_buf; >>>> + unsigned long long vec_buf_len, vec_buf_index, max_pages, found_pages, flags; >>> >>> should it be just unsigned long? >> These internal values are storing data coming from user in struct >> pm_scan_arg in which all variables are 64 bit(__u64) explicitly. This is >> why we have unsigned long long here. It is absolutely necessary. > > vec_buf_len and vec_buf_index can only have values in 0..512 range. > flags has only a few lower bits defined (this is checked on ioctl > entry) and max_pages can be limited to ULONG_MAX. Actually putting `if > (!max_pages || max_pages > ULONG_MAX) max_pages = ULONG_MAX` would > avoid having to check !max_pages during the walk. I'll update. > > Best Regards > Michał Mirosław -- BR, Muhammad Usama Anjum