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 4D3C981732 for ; Tue, 31 Mar 2026 09:56:31 +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=1774950992; cv=none; b=MqwMPPFfEuZIti+eyXQG99ud0mY5UmqkKk4S/kPiNb8wIqRVGBomjAbuEcwDijo20qr9pj6jlt8hZhMKsJujb/EZAOyAi5LjMHw/MXgKE7KwXX7kpc9zMG1MMuEEnlZFtySvpxrVh0dKAmLJb0RdlkimkNtsgNeHx34dpMjUaRA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774950992; c=relaxed/simple; bh=q8CqW5RFkwBpnoolLTU8TCC4V54NnoOYDlrd4aVdQcw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pRPefeC8b1kHC9M6pTkQg5fPRBibnFjT4CYVHGO7pKg53N01Na1+Gmyc/HdrJeDaQrMQsStW1KnmvIE3gsaAq4iFEgOg2UiZmFGUVwPzJ8agGDQS5fR1DUdhdHNYCRU5syOccsvUSbDzBjH5m5Evg2GO2rulnSMAw+ZOP9fr3do= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mLzC4UzY; 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="mLzC4UzY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46FF1C19423; Tue, 31 Mar 2026 09:56:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774950991; bh=q8CqW5RFkwBpnoolLTU8TCC4V54NnoOYDlrd4aVdQcw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mLzC4UzYlXj+2XiKOIfVUvr5YGYadO0n1JZ/9MJXaLCrGuCpWwj3hskxdpdzLNEsS una6NVu2Ka+qyoX4/WFSB2eWOG0tVzO2R0rKnBnwdSWnO+C4pub72YIr+u3o22VkgK OpzJ3iikx71JTHJQqK+Kgi6gexrLN1nuRS5qoJqqWS7aZE/kybgF8ct3DLwkCEL4gy eIPmQRyNHxDzSboFxmCj23SzvKI9uGNG8JR8qSqFmahB0kjOulVHDLh2bZWxWTjAIR FTlShI+4m82ouLMWBVs7AtHlFJfm0/C9MMRNCg+42dbwdKATLT6UM2TbO6yl28CmQv R8ZakVZ2aI4Eg== Date: Tue, 31 Mar 2026 10:56:27 +0100 From: "Lorenzo Stoakes (Oracle)" To: Pedro Falcato Cc: Andrew Morton , "Liam R . Howlett" , Vlastimil Babka , Jann Horn , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] tools/testing/selftests: add merge test for partial msealed range Message-ID: <68ec6eff-9406-4cbf-a886-ce5646929012@lucifer.local> References: <20260331073627.50010-1-ljs@kernel.org> 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: On Tue, Mar 31, 2026 at 10:35:33AM +0100, Pedro Falcato wrote: > On Tue, Mar 31, 2026 at 08:36:27AM +0100, Lorenzo Stoakes (Oracle) wrote: > > Commit 2697dd8ae721 ("mm/mseal: update VMA end correctly on merge") fixed > > an issue in the loop which iterates through VMAs applying mseal, which was > > triggered by mseal()'ing a range of VMAs where the second was mseal()'d and > > the first mergeable with it, once mseal()'d. > > > > Add a regression test to assert that this behaviour is correct. We place it > > in the merge selftests as this is strictly an issue with merging (via a > > vma_modify() invocation). > > > > It also assert that mseal()'d ranges are correctly merged as you'd expect. > > > > The test is implemented such that it is skipped if mseal() is not > > available on the system. > > > > Signed-off-by: Lorenzo Stoakes (Oracle) > > --- > > v2: > > * Added tools/ based header so __NR_mseal should always be available. > > * However, for completeness, also check to see if defined, and assume ENOSYS if > > not. > > * Thanks to Mike for reporting issues in his build on this test! > > > > v1: > > https://lore.kernel.org/all/20260330135011.107036-1-ljs@kernel.org/ > > > > tools/testing/selftests/mm/merge.c | 89 ++++++++++++++++++++++++++++++ > > 1 file changed, 89 insertions(+) > > > > diff --git a/tools/testing/selftests/mm/merge.c b/tools/testing/selftests/mm/merge.c > > index 10b686102b79..f73803b3679a 100644 > > --- a/tools/testing/selftests/mm/merge.c > > +++ b/tools/testing/selftests/mm/merge.c > > @@ -2,6 +2,7 @@ > > > > #define _GNU_SOURCE > > #include "kselftest_harness.h" > > +#include > > #include > > #include > > #include > > @@ -48,6 +49,19 @@ static pid_t do_fork(struct procmap_fd *procmap) > > return 0; > > } > > > > +#ifdef __NR_mseal > > +static int sys_mseal(void *ptr, size_t len, unsigned long flags) > > +{ > > + return syscall(__NR_mseal, (unsigned long)ptr, len, flags); > > +} > > +#else > > +static int sys_mseal(void *ptr, size_t len, unsigned long flags) > > +{ > > + errno = ENOSYS; > > + return -1; > > +} > > +#endif > > + > > FIXTURE_SETUP(merge) > > { > > self->page_size = psize(); > > @@ -1217,6 +1231,81 @@ TEST_F(merge, mremap_correct_placed_faulted) > > ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 15 * page_size); > > } > > > > +TEST_F(merge, merge_vmas_with_mseal) > > +{ > > + unsigned int page_size = self->page_size; > > + struct procmap_fd *procmap = &self->procmap; > > + char *ptr, *ptr2, *ptr3; > > + /* We need our own as cannot munmap() once sealed. */ > > + char *carveout; > > + > > + /* Invalid mseal() call to see if implemented. */ > > + ASSERT_EQ(sys_mseal(NULL, 0, ~0UL), -1); > > + if (errno == ENOSYS) > > + SKIP(return, "mseal not supported, skipping."); > > + > > + /* Map carveout. */ > > + carveout = mmap(NULL, 17 * page_size, PROT_NONE, > > + MAP_PRIVATE | MAP_ANON, -1, 0); > > I think it would be simpler if we did 5 pages (1 for each VMA, plus the two guard VMAs around it). > > > + ASSERT_NE(carveout, MAP_FAILED); > > + > > + /* > > + * Map 3 separate VMAs: > > + * > > + * |-----------|-----------|-----------| > > + * | RW | RWE | RO | > > + * |-----------|-----------|-----------| > > + * ptr ptr2 ptr3 > > + */ > > And now carveout += page_size; would leave us with > > mmap(&carveout[0 * page_size]) > mmap(&carveout[1 * page_size]) > mmap(&carveout[2 * page_size]) > > and we don't need to deal with the arbitrary 5 pages below, which looks a good bit nicer. OK I mean I'm not sure I should be sending a v3 so fast and it's too much for a fix-patch. Given it's cosmetic do we really care? > > > + ptr = mmap(&carveout[page_size], 5 * page_size, PROT_READ | PROT_WRITE, > > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > > + ASSERT_NE(ptr, MAP_FAILED); > > + ptr2 = mmap(&carveout[page_size * 6], 5 * page_size, > > + PROT_READ | PROT_WRITE | PROT_EXEC, > > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > > + ASSERT_NE(ptr2, MAP_FAILED); > > + ptr3 = mmap(&carveout[page_size * 11], 5 * page_size, PROT_READ, > > + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); > > + ASSERT_NE(ptr3, MAP_FAILED); > > + > > + /* > > + * mseal the second VMA: > > + * > > + * |-----------|-----------|-----------| > > + * | RW | RWES | RO | > > + * |-----------|-----------|-----------| > > + * ptr ptr2 ptr3 > > + */ > > + ASSERT_EQ(sys_mseal(ptr2, 5 * page_size, 0), 0); > > + > > + /* Make first VMA mergeable upon mseal. */ > > + ASSERT_EQ(mprotect(ptr, 5 * page_size, > > + PROT_READ | PROT_WRITE | PROT_EXEC), 0); > > + /* > > + * At this point we have: > > + * > > + * |-----------|-----------|-----------| > > + * | RWE | RWES | RO | > > + * |-----------|-----------|-----------| > > + * ptr ptr2 ptr3 > > + * > > + * Now mseal all of the VMAs. > > + */ > > + ASSERT_EQ(sys_mseal(ptr, 15 * page_size, 0), 0); > > + > > + /* > > + * We should end up with: > > + * > > + * |-----------------------|-----------| > > + * | RWES | ROS | > > + * |-----------------------|-----------| > > + * ptr ptr3 > > + */ > > + ASSERT_TRUE(find_vma_procmap(procmap, ptr)); > > + ASSERT_EQ(procmap->query.vma_start, (unsigned long)ptr); > > + ASSERT_EQ(procmap->query.vma_end, (unsigned long)ptr + 10 * page_size); > > +} > > Apart from these nits, the test LGTM > > Acked-by: Pedro Falcato Thanks. > > -- > Pedro