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 3A3741EB19B for ; Wed, 1 Apr 2026 00:58:52 +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=1775005133; cv=none; b=rHintzKSoavUeyo/8c+XLnTRZ170aNKh1fmKuNbGXJTo1+fKzxxS0Zs0IXBqE8DxWJ16cMpwHVTk9eEy0mlZCRgVGd7z3va1hUu0gQAA52wnXGUpYy/k6VVkJX7cwx2zGnVEfxTAx/WcaYaeCdAS/ia4hpIZk8paPc9N1vUuBpg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775005133; c=relaxed/simple; bh=6uvvI24uKLyEUjv5RmaJDmn4RdtHPCKZJX87cczPN3M=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=jaYMi/xAYLIumX17UK/r71+f4OxZMz2Hepq/+dWE4BR8B+zReCqf8f+7qO/i1G8B9lYtlHmxW5HD31pITOanDHHeMeZ7VydcNRkBqOOCaKe4wBlmqtJSvf3qYRAoULaryDeT0hjmqQkuUuLaGOy5SC+0eUQuXKFb7pgEthVP/P4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=tJJdDCpx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="tJJdDCpx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82CABC2BCB0; Wed, 1 Apr 2026 00:58:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1775005132; bh=6uvvI24uKLyEUjv5RmaJDmn4RdtHPCKZJX87cczPN3M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tJJdDCpxZgv01q20W7DE15ULLB4jV5P0rngjpWOIcxhv/oJ5W8LixjUZiH01mmeRC x/C/B0L0xK7uhJ2IQLSQgkV6TfIcY9JPnkveP1nOoUpBmDDfuyUwg6Fq5gChbOa52a SnkXbg1cdfONCkyZwh9eynHhbpz9V3jxj6Q2cneI= Date: Tue, 31 Mar 2026 17:58:51 -0700 From: Andrew Morton To: "Lorenzo Stoakes (Oracle)" Cc: Pedro Falcato , "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: <20260331175851.91867c426e09a5b3eccc1d6f@linux-foundation.org> In-Reply-To: <1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local> References: <20260331073627.50010-1-ljs@kernel.org> <1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) 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-Transfer-Encoding: 7bit On Tue, 31 Mar 2026 11:08:03 +0100 "Lorenzo Stoakes (Oracle)" wrote: > Then again, and contradicting myself elsewhere on fix-patches blah blah blah, > since this is just test code, I checked the below and it works the same and > triggers the regression. > > So maybe we can just apply that? Here's how the two folded together will look: From: "Lorenzo Stoakes (Oracle)" Subject: tools/testing/selftests: add merge test for partial msealed range Date: Tue, 31 Mar 2026 08:36:27 +0100 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 asserts 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. [ljs@kernel.org: simplifications per Pedro] Link: https://lkml.kernel.org/r/1c9c922d-5cb5-4cff-9273-b737cdb57ca1@lucifer.local Link: https://lkml.kernel.org/r/20260331073627.50010-1-ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) Cc: David Hildenbrand Cc: Jann Horn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Pedro Falcato Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- tools/testing/selftests/mm/merge.c | 89 +++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) --- a/tools/testing/selftests/mm/merge.c~tools-testing-selftests-add-merge-test-for-partial-msealed-range +++ a/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 * 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_faul 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, 5 * page_size, PROT_NONE, + MAP_PRIVATE | MAP_ANON, -1, 0); + ASSERT_NE(carveout, MAP_FAILED); + + /* + * Map 3 separate VMAs: + * + * |-----------|-----------|-----------| + * | RW | RWE | RO | + * |-----------|-----------|-----------| + * ptr ptr2 ptr3 + */ + ptr = mmap(&carveout[page_size], page_size, PROT_READ | PROT_WRITE, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr, MAP_FAILED); + ptr2 = mmap(&carveout[2 * page_size], page_size, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); + ASSERT_NE(ptr2, MAP_FAILED); + ptr3 = mmap(&carveout[3 * page_size], 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, page_size, 0), 0); + + /* Make first VMA mergeable upon mseal. */ + ASSERT_EQ(mprotect(ptr, 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, 3 * 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 + 2 * page_size); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap = &self->procmap; _