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 7CD2FCDE021 for ; Fri, 14 Nov 2025 08:11:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BF1A88E0007; Fri, 14 Nov 2025 03:11:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BA21C8E0002; Fri, 14 Nov 2025 03:11:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A948E8E0007; Fri, 14 Nov 2025 03:11:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 9431E8E0002 for ; Fri, 14 Nov 2025 03:11:49 -0500 (EST) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 31B5D88529 for ; Fri, 14 Nov 2025 08:11:49 +0000 (UTC) X-FDA: 84108493938.25.D77ECDF Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf13.hostedemail.com (Postfix) with ESMTP id 8E3FC20002 for ; Fri, 14 Nov 2025 08:11:47 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MT9IHfhL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1763107907; a=rsa-sha256; cv=none; b=aj63b72OJ7ECv5Z23HPZxWmAFLbOM955wfUs79Iod48zk7koKKUMLX3yKnQ+PU04E5Vqss nGqfg6HcolAMivniRHszhjdHsYQZ+uYeFxbPRw5kjz2fcswa7wo/IbT1wmj+thn3RoP0Wx Ltdr3+2ve6TTWMRfkdKa4XL2nVSk7zw= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=MT9IHfhL; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1763107907; 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=A1F9g0B6grh1pyEbdws2Ys5lAC9QN1XTCTeZvmfIvs8=; b=RALBYueAaSy/ZQbcaKQallNdI2TWVl/P9JPlyL+ua+HUwtjBIYb/LHKjAnzx8Os5TBaXjp +uqF2Wc9XkxeE50N93LkYghtASB3GkcXxHgLR1hYMlfT4ztAjVmgm2VOHcoHwMrrveRPVP eLmNRykS4Fqu7yj1cfBHM7MGQ4Fe8gY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 657B243F09; Fri, 14 Nov 2025 08:11:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39037C19421; Fri, 14 Nov 2025 08:11:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763107906; bh=OhGJvBDuLbsZuOLjHyEX6xIRl+rLMcdKrk/4+J4TeoY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=MT9IHfhLgZNygWpWG+dIRg6p7RUMUEJnK40W4JZjMG0Yi6v+emGp8fU39Dv5V938i RfBl//v9Ge3H/xItQ2DqNjBiq9ZOnM4UIPaxoDcfBXafM4kkEDITA9SSqc2sSdXGVq o7Hu4mvfGFxlFKsWc/nNdJvQQlg9sWoXCT9DHE3oYDYq6WZMkCe7PG6unlXomQBHHk UaXZwAnG6UHtepYc44yd4I52ghf1b8H64CrQCGiRPzXDn9UGEQmvBdJZMaPf1ClPot aPgBmOUnsHTiqmRoTeu8rOVEFVk+Rd+smmC0ATKdv/AoT0lOdj+uCLIh1F+0T5pdCu oCyn+0Y2SCsIw== Message-ID: <9d30836b-9ddb-4432-aa39-85e32c2ea645@kernel.org> Date: Fri, 14 Nov 2025 09:11:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: fix division-by-zero in uffd-unit-tests To: Andrew Morton , Lorenzo Stoakes Cc: Carlos Llamas , 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" References: <20251113034623.3127012-1-cmllamas@google.com> <4a60a703-d9c2-46a8-83b4-a7ecff7f6ba2@lucifer.local> <20251113153205.6507ecb308e7d09362905da7@linux-foundation.org> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251113153205.6507ecb308e7d09362905da7@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8E3FC20002 X-Rspamd-Server: rspam07 X-Stat-Signature: e7tsjzanx4jdwxxkaejnfpm7usdrndrc X-Rspam-User: X-HE-Tag: 1763107907-57582 X-HE-Meta: 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 COnjfV7F /luqBcXX9IUvZS+WxXqa3HmPaCWtHx3mVl9mz 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 14.11.25 00:32, Andrew Morton wrote: > 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? I thought we were so inconsistent on that that it ends up being a wasted effort to even try taking care about stability of selfests in stable trees. -- Cheers David