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 E4DA0C04A6A for ; Thu, 3 Aug 2023 15:25:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237093AbjHCPZa (ORCPT ); Thu, 3 Aug 2023 11:25:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53782 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237097AbjHCPZ2 (ORCPT ); Thu, 3 Aug 2023 11:25:28 -0400 Received: from mail-ed1-x533.google.com (mail-ed1-x533.google.com [IPv6:2a00:1450:4864:20::533]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E585130FD for ; Thu, 3 Aug 2023 08:25:26 -0700 (PDT) Received: by mail-ed1-x533.google.com with SMTP id 4fb4d7f45d1cf-521e046f6c7so10607a12.1 for ; Thu, 03 Aug 2023 08:25:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1691076325; x=1691681125; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=3i6erIjjtN6lPgXcEJaSwL8Ki+NeE4iek/Jz08H42Eg=; b=1/JqHb/LG7PoqyNlz01wER9UTCkrpH9M2FU4Vbd6r/CQI4UW/uMBfpHnxSvH72WDZa 17EGkY/9+0GvLunkXQuT7Fj49JG1SV574d0CzUHATzQilyCkac+gLSTBBXJIZaVwWa8s cpGdP8Hx/x2GWYeMp4ndHvJGpBnn6RxkjNP6yBq0qKblG8zGXopTU7sKzKEIb2z2fZkO BdPPCqQxqGQIeeNv0DmWgOhQUsoK2E/MGim7smaG3/IvHHUGhOOYRpcldpDLCveM/scO t0H6kHpbTnshhZS2Vd+Rog+eB2YM23VKEVtMN5/XEaDpvaH5k2NGGFIFniZnJgDxkngD M2uQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691076325; x=1691681125; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3i6erIjjtN6lPgXcEJaSwL8Ki+NeE4iek/Jz08H42Eg=; b=Pbfm55n3AA/Bzg2MAsHyoocXes5Qaown77csDxg00o21HceFGTYFvDJSs/BqW5AA8G +q01Yb/fzefX/iUlrY/IEpa+I6Q0cJvZatb4LinYphXBIKS+pCYhSvSAtQ+BHPpTaWS5 3gNLlYViSt1zglDpDxPiNS9W0YW77iGaOQQKeh5zPJ7ZABsQe6TjUsMozIOgWD8jdIiX GXL9+O4WsmIOmG2vuye9uuD/P5zRfMcw7QwwgUJTXd7ttwpMj2llzOF7Tg2UkIu6J51p NHdUm4XLgEuj3vbhYVZVjlWSLnYeY1ELnuhY2FP0DVOliLHe5FG+jA1uMlD1aP4EvRpZ k6ow== X-Gm-Message-State: ABy/qLZXnxYGfu0GMKey4n5Tc/o9iyZVOQdJrACvlTyobZHzJOZ8uiz1 jzB4+QySfyv/kWe0JLlcD36nRUuv/gP7LaO7e9KBtw== X-Google-Smtp-Source: APBJJlHEkuDfzpxiBsrJVo+Ct415MwqYT9+g40+EOyv9eJZgbwZFuwhEjHnaDyGp8XxHI0wEbUXhD/X+RM4zDUX956g= X-Received: by 2002:a50:8e16:0:b0:51e:16c5:2004 with SMTP id 22-20020a508e16000000b0051e16c52004mr528078edw.6.1691076325295; Thu, 03 Aug 2023 08:25:25 -0700 (PDT) MIME-Version: 1.0 References: <20230727093637.1262110-1-usama.anjum@collabora.com> <20230727093637.1262110-3-usama.anjum@collabora.com> In-Reply-To: From: =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Date: Thu, 3 Aug 2023 17:25:13 +0200 Message-ID: Subject: Re: [PATCH v26 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs To: Andrei Vagin Cc: Muhammad Usama Anjum , 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, =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, 3 Aug 2023 at 17:09, Andrei Vagin wrote: > On Thu, Jul 27, 2023 at 02:36:34PM +0500, Muhammad Usama Anjum wrote: [...] > > + n_pages =3D (*end - addr) / PAGE_SIZE; > > + if (check_add_overflow(p->found_pages, n_pages, &total_pages) || > > + total_pages > p->arg.max_pages) { > > why do we need to use check_add_overflow here? > > > + size_t n_too_much =3D total_pages - p->arg.max_pages; > > it is unsafe to use total_pages if check_add_overflow returns non-zero. Since we're adding unsigned integers, this is well defined even after overf= low. Best Regards Micha=C5=82 Miros=C5=82aw