From nobody Sat Feb 7 06:21:39 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 EDDA4310624; Wed, 29 Oct 2025 12:22:45 +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=1761740566; cv=none; b=omEqrFqggUoE2gjRplVFXnPl2ylX5D1DE90Y2s9061OGNDjf+PIx4Jh7zbWuBeiOa0StW6uVuEuOYCHhbwP+JBGB4PhoY3WV+9BJVse7gCT5FzhfbcX9+TzmMs4LFpT0vcsRFfIxqsJz00cm4You5fAABx5y1Dn1qaARqFlwhW8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761740566; c=relaxed/simple; bh=aUj6NRVDEfXAvY88G+wOpYmY1IAUvRXs+4FwCz1W+QY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=f/U0XpyapGBmoyqD4U+xpQ8PrTd5DZF42YFvL+s+7SKuOZw+UdUfwjF/dw7lqKgEQuIGxJ1ZR/OaL/POl2dSY+U0GLNkXQ1JKSvRf66TofvwjNmaL8YkL6FOPZHmDp64mYO+wfFKs/eVEpTkOWaVc0W8NlAtOsIqz9mAvOcr0gw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jnw1aMB2; 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="jnw1aMB2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1471CC4CEFD; Wed, 29 Oct 2025 12:22:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761740565; bh=aUj6NRVDEfXAvY88G+wOpYmY1IAUvRXs+4FwCz1W+QY=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=jnw1aMB2/mFYOeS4oJ7GrQyGWmVZBCpi/0ToK43HUjZMLS3fWTnMTDCOwA7yRosiC 2rga7pe3YBN5aG0HYr264QwmwGInYFeMLwL6ewlDX5Z2MQpqhd6aE4y/+WpTOSeHfx hp3EL+ygd6CMjN5hN/RleS7csNqh0oifawdtxGDNEPlCX2LRM0OmIpWXIazuHBQObm beMMkXnegQ+gc+1mmzT6lX3VZDxmXVinM8hzm/bytSrKnOwdXwtW2/RKFGAnLotXjz 8C5TgXL33PqrZpoFQLV3iZG4uD5wN/9LdIbMEJSE7L+9ftLofCHfSEHkYwfm++XJtZ xJ3rCi2djX46g== From: Christian Brauner Date: Wed, 29 Oct 2025 13:20:38 +0100 Subject: [PATCH v4 25/72] selftests/namespaces: third active reference count tests 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251029-work-namespace-nstree-listns-v4-25-2e6f823ebdc0@kernel.org> References: <20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org> In-Reply-To: <20251029-work-namespace-nstree-listns-v4-0-2e6f823ebdc0@kernel.org> To: linux-fsdevel@vger.kernel.org, Josef Bacik , Jeff Layton Cc: Jann Horn , Mike Yuan , =?utf-8?q?Zbigniew_J=C4=99drzejewski-Szmek?= , Lennart Poettering , Daan De Meyer , Aleksa Sarai , Amir Goldstein , Tejun Heo , Johannes Weiner , Thomas Gleixner , Alexander Viro , Jan Kara , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, bpf@vger.kernel.org, Eric Dumazet , Jakub Kicinski , netdev@vger.kernel.org, Arnd Bergmann , Christian Brauner X-Mailer: b4 0.15-dev-96507 X-Developer-Signature: v=1; a=openpgp-sha256; l=3551; i=brauner@kernel.org; h=from:subject:message-id; bh=aUj6NRVDEfXAvY88G+wOpYmY1IAUvRXs+4FwCz1W+QY=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWQysfW+Wf21aMLcuFV1TJZp4Zq9bszFGZe/PIqPW7jMQ t8xdcq2jlIWBjEuBlkxRRaHdpNwueU8FZuNMjVg5rAygQxh4OIUgIk8fMHwz+qY5PIH8hK36kVc gi6fnhcccSP464xly9Zbvohv3egSv47hN/vb8I9H0wpNd4s5cf21tfpoEnVdhI/5nHbiVZ46vSJ /dgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Test that a namespace remains active while a process is using it, even after the creating process exits. Signed-off-by: Christian Brauner --- .../selftests/namespaces/ns_active_ref_test.c | 124 +++++++++++++++++= ++++ 1 file changed, 124 insertions(+) diff --git a/tools/testing/selftests/namespaces/ns_active_ref_test.c b/tool= s/testing/selftests/namespaces/ns_active_ref_test.c index 7cade298c754..c2e34de7a3a9 100644 --- a/tools/testing/selftests/namespaces/ns_active_ref_test.c +++ b/tools/testing/selftests/namespaces/ns_active_ref_test.c @@ -152,4 +152,128 @@ TEST(ns_inactive_after_exit) ASSERT_TRUE(errno =3D=3D ENOENT || errno =3D=3D ESTALE); } =20 +/* + * Test that a namespace remains active while a process is using it, + * even after the creating process exits. + */ +TEST(ns_active_with_multiple_processes) +{ + struct file_handle *handle; + int mount_id; + int ret; + int fd; + int pipefd[2]; + int syncpipe[2]; + pid_t pid1, pid2; + int status; + char buf[sizeof(*handle) + MAX_HANDLE_SZ]; + char sync_byte; + + /* Create pipes for communication */ + ASSERT_EQ(pipe(pipefd), 0); + ASSERT_EQ(pipe(syncpipe), 0); + + pid1 =3D fork(); + ASSERT_GE(pid1, 0); + + if (pid1 =3D=3D 0) { + /* First child - creates namespace */ + close(pipefd[0]); + close(syncpipe[1]); + + /* Create new network namespace */ + ret =3D unshare(CLONE_NEWNET); + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Open and get handle */ + fd =3D open("/proc/self/ns/net", O_RDONLY); + if (fd < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + handle =3D (struct file_handle *)buf; + handle->handle_bytes =3D MAX_HANDLE_SZ; + ret =3D name_to_handle_at(fd, "", handle, &mount_id, AT_EMPTY_PATH); + close(fd); + + if (ret < 0) { + close(pipefd[1]); + close(syncpipe[0]); + exit(1); + } + + /* Send handle to parent */ + write(pipefd[1], buf, sizeof(*handle) + handle->handle_bytes); + close(pipefd[1]); + + /* Wait for signal before exiting */ + read(syncpipe[0], &sync_byte, 1); + close(syncpipe[0]); + exit(0); + } + + /* Parent reads handle */ + close(pipefd[1]); + ret =3D read(pipefd[0], buf, sizeof(buf)); + close(pipefd[0]); + ASSERT_GT(ret, 0); + + handle =3D (struct file_handle *)buf; + + /* Create second child that will keep namespace active */ + pid2 =3D fork(); + ASSERT_GE(pid2, 0); + + if (pid2 =3D=3D 0) { + /* Second child - reopens the namespace */ + close(syncpipe[0]); + close(syncpipe[1]); + + /* Open the namespace via handle */ + fd =3D open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + if (fd < 0) { + exit(1); + } + + /* Join the namespace */ + ret =3D setns(fd, CLONE_NEWNET); + close(fd); + if (ret < 0) { + exit(1); + } + + /* Sleep to keep namespace active */ + sleep(1); + exit(0); + } + + /* Let second child enter the namespace */ + usleep(100000); /* 100ms */ + + /* Signal first child to exit */ + close(syncpipe[0]); + sync_byte =3D 'X'; + write(syncpipe[1], &sync_byte, 1); + close(syncpipe[1]); + + /* Wait for first child */ + waitpid(pid1, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); + + /* Namespace should still be active because second child is using it */ + fd =3D open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY); + ASSERT_GE(fd, 0); + close(fd); + + /* Wait for second child */ + waitpid(pid2, &status, 0); + ASSERT_TRUE(WIFEXITED(status)); +} + TEST_HARNESS_MAIN --=20 2.47.3