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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 834C1CD98F7 for ; Thu, 13 Nov 2025 23:32:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A06BA8E0005; Thu, 13 Nov 2025 18:32:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DEBA8E0002; Thu, 13 Nov 2025 18:32:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 91ACE8E0005; Thu, 13 Nov 2025 18:32:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7F6BF8E0002 for ; Thu, 13 Nov 2025 18:32:10 -0500 (EST) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 3258412CB3D for ; Thu, 13 Nov 2025 23:32:10 +0000 (UTC) X-FDA: 84107184420.30.E1FFF83 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf01.hostedemail.com (Postfix) with ESMTP id 746C540007 for ; Thu, 13 Nov 2025 23:32:08 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=DsvSKa22; spf=pass (imf01.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763076728; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=0ROHQk+fol3lQxsTuKjXUjYmTsHOdhYS8qfsfiIH5Rk=; b=4SwygbDx+KljLz62Z6YN21tMq5rRDnLs9uU67MEoaZyqVWr/CtofxVnBso8HFQ4pUz9Xru 9vWHlb1q6kMs/UQl4BOhJVhGcgy9b51T6nr4w9iBNW76/+4Jo5eDKzsTW+olEYjTKier5x QidvKoLxqO0EUNzBWKpQ/Cqj4mh811Y= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=DsvSKa22; spf=pass (imf01.hostedemail.com: domain of akpm@linux-foundation.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1763076728; a=rsa-sha256; cv=none; b=vOGEHN+FGkkOEwPgs+GrLg6Kj3d9sFNxO0ejsH28iqn0xrUpibAwzMpuCPnHaxdiep6d90 blfjFjDI2Zl9/v3c1n97iFd5zLGrPsTAEZQAabGlSEiCwgb/MXxYG/H8F7H1eXKwKRbhcM fY5tVlGm6vQBYlHWkp98tPORo2aVXtk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 63D9543BCA; Thu, 13 Nov 2025 23:32:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79B28C4DE01; Thu, 13 Nov 2025 23:32:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1763076727; bh=0/Wu2Fbf5XL6YXzMCsU9T/GGUPwbFh2GCmkLRrlFK+U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DsvSKa22dmOLI50W4oxTVoFKUf84nqZZR5Kh5pCAiFxU5Wy5G+9iOCJEJsNSksOej T/LZE//2cuhxzpEMmDR5zf9vE5QUSJLH0h+MC5MLMsZSEbFyQmNbhuyjhLOHIzjjGX 8AuW1DiXEdj4xAwcqSJ35ghaR6Oj7If5wSIObnJw= Date: Thu, 13 Nov 2025 15:32:05 -0800 From: Andrew Morton To: Lorenzo Stoakes Cc: Carlos Llamas , "David Hildenbrand (Red Hat)" , Peter Xu , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Ujwal Kundur , Brendan Jackman , kernel-team@android.com, linux-kernel@vger.kernel.org, stable@vger.kernel.org, "open list:MEMORY MANAGEMENT - USERFAULTFD" , "open list:KERNEL SELFTEST FRAMEWORK" Subject: Re: [PATCH] selftests/mm: fix division-by-zero in uffd-unit-tests Message-Id: <20251113153205.6507ecb308e7d09362905da7@linux-foundation.org> In-Reply-To: References: <20251113034623.3127012-1-cmllamas@google.com> <4a60a703-d9c2-46a8-83b4-a7ecff7f6ba2@lucifer.local> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 746C540007 X-Stat-Signature: yt4wa4714wtd8fqdzyqr7n9f7k8xrero X-Rspam-User: X-HE-Tag: 1763076728-221720 X-HE-Meta: U2FsdGVkX1+a40jH67hIVZz8r22tqqUmP2e74oI+vWJ+zDMfO7Br4oMZwW91zMvMnge5ceHY5ZsZCzxNcGQaDTQ/L+9gn7MpADISldMNClxWqKL6EgJXEN+kbxiBvTm+LU91cxi62E0msB/6gYrPpvICeav2V3Wc0SPxhtodEAUXViBb/mXiJJ3c3cC8sHo4jwo1ofmWonpNOHSbqa+T4dWUuFfeIuxiiw85nOj/uEuFD6Y8EtbHr21Rh1NuYoDoDZZ9JvGi15NjzehepUXizSAaIurCY0lpJy0SaD6ke0TbMA8BtVymU5+P+vIGtJ/fdtbY5/RdhqCDhiU/N1mnJyqJ08LpsRV/g/ixIiDD59kypVXhr7DobNN6NYCIdojLuYuDg/BEVoB5y9+wWBUNgvX3CkEmA273CXI+hpkLEAY4/hOF/GmtxLPU9ygGg4w7dkH9+nTsW5h8t5NgAOJw4SskfiTCCq+GSVzhuEkBTLa9nsHxKdronnrFkKSjVK5y17Q9TjfwdiKv1sANhCOYEUqZPlDlv0AsCrZ4Ikak3zQHO4gBjOOjLyNaCDJnQuvmLm8+sMBBcq8OEoeyU/dms/8lWTnA3EbFTrQ9mA87eFTWMzI6wFCmGjcotM9trConBGYicsJQ4W6+ACGtUXsEwjHCo84YV0dCN3AiBtG+EymkBdsrlXNMumzvwTuMug4vivW6lZDHqgHAT8+1U4xZm/01hfZ9uAKFiCVN7e3ywip3/UcdDKpKqWGdPGko499M3dGs7WoulrZJRqNUCJEGx7x99sVgEZ3JUs3/9qmAMlhW9n5CilTfD0vJxuY6HmFMCdq44JFdhyxR9z56Ut4ZoFRrXrpAtF+BOnl/muYLdvW/nP95R94dchTOrmNOvC3K9OVFZvwmqtY+inqKTMVINjqEpzmnNNT70iCb4Bxq5YN3pj85iuscaIefYJRLUnDfcy+vizAz0wzmwUTVf5z v+RrgyXZ Esuzhx9xcjcTgSqzYsbrVaYhgQyw9+bhyWrkjKCmFV/speG+WATaTEiPJdT+kQ4ND7t4CI9B1jjiVWTAc2LXw8JvzP0kmG9XKyuEnK81fSgJLNoGNmboPMzjuR7KXrGq3TOUdShrACW28Mm49s+op+GjvfmSpHr4SvWvwng5IzK8sGheJDDcy4HZMaPBi5S4Zb0ADwLMxm497iT+zMxFiJSaxfS9goUOhVRnnmT2AaIxMXb6HNy6YGdEfaI8i2VHBhp5pY64yTRCwlljIZlFhHiNL1tNxyIFS+FswNwyI3rMgj75bDGso0bm2MP9gZFDrnDUrEtKVjPHbkwa+pK38u9TJ+ypToMQhS7tUQyNJxgHm8U0NNAvNTsDG+w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 13 Nov 2025 15:03:06 +0000 Lorenzo Stoakes wrote: > On Thu, Nov 13, 2025 at 03:01:25PM +0000, Carlos Llamas wrote: > > On Thu, Nov 13, 2025 at 09:54:37AM +0000, Lorenzo Stoakes wrote: > > > On Thu, Nov 13, 2025 at 10:06:42AM +0100, David Hildenbrand (Red Hat) wrote: > > > > On 13.11.25 04:46, Carlos Llamas wrote: > > > > > Commit 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global > > > > > vars into struct") moved some of the operations previously implemented > > > > > in uffd_setup_environment() earlier in the main test loop. > > > > > > > > > > The calculation of nr_pages, which involves a division by page_size, now > > > > > occurs before checking that default_huge_page_size() returns a non-zero > > > > > This leads to a division-by-zero error on systems with !CONFIG_HUGETLB. > > > > > > > > > > Fix this by relocating the non-zero page_size check before the nr_pages > > > > > calculation, as it was originally implemented. > > > > > > > > > > Cc: stable@vger.kernel.org > > > > > > > > Do we CC stable on unit tests? From my recollection, no. > > > > > > Yeah please let's not. > > > > Oops, I keep getting confused about this Cc stable thing. Please let me > > know if a v2 dropping the tag is needed. > > No need, Andrew should spot the objection and drop the tag :) I actually add cc:stable tags to selftests fixes! Because why not. Why leave people running known-to-be-buggy code when our backporting processes are so well-functioning and lightweight? I'm not getting the objection?