From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E5AD3112BB; Thu, 13 Nov 2025 11:42:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763034134; cv=none; b=Q0U9IquTV1/MNtkhppuKRAPrOUP+oy3mB997zsgCKJTeXygxXiidEnxvMgTy2kL8LrGXZOywn+GpMNihGTDnh+GMUpJfePJHUCDa5nU5Csyk1KML4/J2HY135mQJ3Fb+g5+tV1wz1IedjUBZHSgtwARDw+xfJaGEwbBtg7U2uqQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763034134; c=relaxed/simple; bh=STrLN9TaMedzhy/AV3DPEXhd1qFmA8sZ1GjlOFXHjO4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=YemcIK6+B+IodXejH4+Qnq4Y7QC8Xpesx0iZzpyDVIyg1vdu/GF4sDX6gLOfB/ytsEBdsDOxT5NORJ4Fe7dqc1PAtjMLQ3DdOEln5EFtDLI5rN0U+zcATutZWqfvz697+/Fh5rkgacQOERLxBHTbWNwPIo3+VnUYY9jwIf1jk4k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VU146KzH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VU146KzH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC98CC4AF09; Thu, 13 Nov 2025 11:42:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763034134; bh=STrLN9TaMedzhy/AV3DPEXhd1qFmA8sZ1GjlOFXHjO4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VU146KzHCHjuBsPUsgTIzQH0cXL+9V8Z6BJqbMtO79x84t7yUlDckcL2h7qf9bRFg obF3uDlCXmobGcjhbUpr3Wa7VgZ6PIAjSBYOzjxqEbNq9uGJvWb8yDvfj08/PQ/g6a D13+Zzxmn8YrUz2QFj168p5x6HYuAqYEW1zTQ3zSxxfbU4fE2KkhZKF5gYoWk1cLlw MTsxXNGTVAzosrfZAxLZ83pNPnN8uj3mBnqlX8pye1ZjQHW1YlAcQHdvIY6394FQSB 1aQEUiLoVhEL9j6cYVFgedr30vAUY4djX/mqiBY0rzyeqOfTiityRADnFo5V5M65hg pEb7zGtClVyQA== Date: Thu, 13 Nov 2025 13:42:04 +0200 From: Mike Rapoport To: Carlos Llamas Cc: Andrew Morton , Peter Xu , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , 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: References: <20251113034623.3127012-1-cmllamas@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251113034623.3127012-1-cmllamas@google.com> On Thu, Nov 13, 2025 at 03:46:22AM +0000, 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 > Fixes: 4dfd4bba8578 ("selftests/mm/uffd: refactor non-composite global vars into struct") > Signed-off-by: Carlos Llamas Agree with what David and Lorenzo said about cc:stable. Reviewed-by: Mike Rapoport (Microsoft) > --- > tools/testing/selftests/mm/uffd-unit-tests.c | 15 +++++++-------- > 1 file changed, 7 insertions(+), 8 deletions(-) > > diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c > index 9e3be2ee7f1b..f917b4c4c943 100644 > --- a/tools/testing/selftests/mm/uffd-unit-tests.c > +++ b/tools/testing/selftests/mm/uffd-unit-tests.c > @@ -1758,10 +1758,15 @@ int main(int argc, char *argv[]) > uffd_test_ops = mem_type->mem_ops; > uffd_test_case_ops = test->test_case_ops; > > - if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) > + if (mem_type->mem_flag & (MEM_HUGETLB_PRIVATE | MEM_HUGETLB)) { > gopts.page_size = default_huge_page_size(); > - else > + if (gopts.page_size == 0) { > + uffd_test_skip("huge page size is 0, feature missing?"); > + continue; > + } > + } else { > gopts.page_size = psize(); > + } > > /* Ensure we have at least 2 pages */ > gopts.nr_pages = MAX(UFFD_TEST_MEM_SIZE, gopts.page_size * 2) > @@ -1776,12 +1781,6 @@ int main(int argc, char *argv[]) > continue; > > uffd_test_start("%s on %s", test->name, mem_type->name); > - if ((mem_type->mem_flag == MEM_HUGETLB || > - mem_type->mem_flag == MEM_HUGETLB_PRIVATE) && > - (default_huge_page_size() == 0)) { > - uffd_test_skip("huge page size is 0, feature missing?"); > - continue; > - } > if (!uffd_feature_supported(test)) { > uffd_test_skip("feature missing"); > continue; > -- > 2.51.2.1041.gc1ab5b90ca-goog > -- Sincerely yours, Mike.