From nobody Wed Apr 1 12:31:59 2026 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 846993BE16E for ; Tue, 31 Mar 2026 07:36:35 +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=1774942595; cv=none; b=OjvLlPZ8GP+YN0nUFfOWiucTLZ5zr5PoH93iG1bgDRARpb8mcOqN0Su5n5gEm4mZs6ERE5fMpuhiqutCLhDEmkpbo9pQ4TsS9dm1goVxB4X9dQwBNjDCVgtgoZxwFaMGx5om/3zVkW+mvAdonnCBBG9F0DE5fqYtqE3tqkWefgA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774942595; c=relaxed/simple; bh=1aLP5pU2VJqnqi+qS5pxWmVzBh4A4EESl8jLJtYmit4=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=f17OKBxGLy8xIylaPSWVPa+zMl2WQ7SKEYvksXxFVzzMvPlKpDdMQ5hA0DFKXJEEwiIly0ldfeMVCyvFlbM2TX1hI1MQLdv1nsAmEV3eT6e1pAHOJmMpBK0qObD0TiFg+XpcBwhS06C7P171Qiiw61zd1Fxf/5xdrwzupilU2Co= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IUbcizkl; 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="IUbcizkl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF981C19424; Tue, 31 Mar 2026 07:36:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774942595; bh=1aLP5pU2VJqnqi+qS5pxWmVzBh4A4EESl8jLJtYmit4=; h=From:To:Cc:Subject:Date:From; b=IUbcizklv/BBBOz7QZr8ip9oeUH9fmeVbVP77kIC/XiINHE/wIJPiyCYWApJojsyp 0y48Q6C6hrxVB0RQ8XYNdO1AjV/wHfDJpbAYEm3KdUicAKDKh1XX9snBBx747UpUzA mFDHk7nW2vEx45Wh9PTZkKjpETba79IXYswvPA5sasQ3sueNbYDBs5X4a9kmAYgTE0 9Aq5c4x3G9dme/KTMoh2IQ2tnbW5HhhVQCRVOX8QZzqMXbcPd0ve62ZRN3HitJygMd +/ksdGYNrlpLzLXVr97cJUS3qOjUaL2V9a2QT0EJX7tBDoGwanmo6G0xl0m5adom2K 1XBheC7M8Ki8Q== From: "Lorenzo Stoakes (Oracle)" To: Andrew Morton Cc: "Liam R . Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] tools/testing/selftests: add merge test for partial msealed range Date: Tue, 31 Mar 2026 08:36:27 +0100 Message-ID: <20260331073627.50010-1-ljs@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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) Acked-by: Pedro Falcato --- v2: * Added tools/ based header so __NR_mseal should always be available. * However, for completeness, also check to see if defined, and assume ENOSY= S 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/m= m/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 =3D ENOSYS; + return -1; +} +#endif + FIXTURE_SETUP(merge) { self->page_size =3D 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 =3D self->page_size; + struct procmap_fd *procmap =3D &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 =3D=3D ENOSYS) + SKIP(return, "mseal not supported, skipping."); + + /* Map carveout. */ + carveout =3D mmap(NULL, 17 * 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 =3D 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 =3D 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 =3D 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); +} + TEST_F(merge_with_fork, mremap_faulted_to_unfaulted_prev) { struct procmap_fd *procmap =3D &self->procmap; -- 2.53.0