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b=j1xr4ow13eYqPzo66Vy7ar9HIiMtgRGMDsnKwNvIASkjsql8yqCEakVNO1Pv2rBhe aL183bC/PXsEwZZFmWvwz/XivGToT7uyDgmXzJPsrn3sqaxTrpEBqQSHT/zLZdDMoo AuKQwlKDV1wQBYhYDT/hDJPFjV+2Z5C2JqO7P1RF2gywkf+6Zu66QgSrha64T5/3u4 vq1zFsskLW5KQtI5VIgRfidZRWs5DENxK5TsIvH+zwuI9MBksbIT18PQbSygstt5aT 2xPO0Lr1s/uOqZ/9UEPJuS9mJotn9KpZ4l8KFjJYKmJRSOqjBGqaJSr3lXDYDOrn+3 RkgyjKWYlkchw== From: Pratyush Yadav To: Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Shuah Khan , Andrew Morton , Usama Arif Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v3 1/6] selftests/liveupdate: add framework for memfd tests Date: Sat, 4 Apr 2026 10:24:44 +0000 Message-ID: <20260404102452.4091740-2-pratyush@kernel.org> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog In-Reply-To: <20260404102452.4091740-1-pratyush@kernel.org> References: <20260404102452.4091740-1-pratyush@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 46AC7180007 X-Stat-Signature: o78oifzju1igwzzzm3g63gkqo5cws8fc X-HE-Tag: 1775298306-490300 X-HE-Meta: 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Pratyush Yadav (Google)" Currently memfd preservation using LUO is only tested indirectly via the luo_multi_session or luo_kexec_simple tests. Their main purpose is to test other live update functionality. Add a framework for writing memfd tests. The framework hooks into the kselftest harness, but adds some things on top to make it suitable for live update. The LUO FD (/dev/liveupdate) can only be opened by one process at a time. Each test runs in its own process. This means the LUO FD must be owned by the main process and shared to children. main() opens the LUO FD and shares it to child runners using a global variable. Live update tests run in two stages. One before kexec and one after. Detect the stage using a special state session. If the session is present, it means the test is in post-kexec state. Additionally, take in an optional --stage argument that lets callers specify expected stage. This is useful as a safety net to catch LUO core failures. If LUO core fails to preserve the state session properly, this option can help detect this and fail early. Since the option is not recognized by the kselftest harness, remove it from argv before calling test_harness_run(). Reviewed-by: Mike Rapoport (Microsoft) Signed-off-by: Pratyush Yadav (Google) --- tools/testing/selftests/liveupdate/Makefile | 1 + .../testing/selftests/liveupdate/luo_memfd.c | 78 +++++++++++++++++++ 2 files changed, 79 insertions(+) create mode 100644 tools/testing/selftests/liveupdate/luo_memfd.c diff --git a/tools/testing/selftests/liveupdate/Makefile b/tools/testing/selftests/liveupdate/Makefile index 080754787ede..051daae55eec 100644 --- a/tools/testing/selftests/liveupdate/Makefile +++ b/tools/testing/selftests/liveupdate/Makefile @@ -6,6 +6,7 @@ TEST_GEN_PROGS += liveupdate TEST_GEN_PROGS_EXTENDED += luo_kexec_simple TEST_GEN_PROGS_EXTENDED += luo_multi_session +TEST_GEN_PROGS_EXTENDED += luo_memfd TEST_FILES += do_kexec.sh diff --git a/tools/testing/selftests/liveupdate/luo_memfd.c b/tools/testing/selftests/liveupdate/luo_memfd.c new file mode 100644 index 000000000000..c1f3275963dc --- /dev/null +++ b/tools/testing/selftests/liveupdate/luo_memfd.c @@ -0,0 +1,78 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (c) 2026, Google LLC. + * Pratyush Yadav (Google) + */ + +/* + * Selftests for memfd preservation via LUO. + */ + +#include +#include +#include +#include +#include + +#include + +#include "../kselftest.h" +#include "../kselftest_harness.h" + +#include "luo_test_utils.h" + +#define STATE_SESSION_NAME "luo-state" +#define STATE_MEMFD_TOKEN 1 + +static int luo_fd = -1; +static int stage; + +int main(int argc, char *argv[]) +{ + int expected_stage = 0; + int session; + + /* + * The test takes an optional --stage argument. This lets callers + * provide the expected stage, and if that doesn't match the test errors + * out. + * + * Look for the stage. Since test_harness_run() doesn't recognize it, + * once found, remove it from argv. + */ + for (int i = 1; i < argc; i++) { + if (strcmp(argv[i], "--stage") == 0) { + if (i + 1 < argc) { + expected_stage = atoi(argv[i + 1]); + memmove(&argv[i], &argv[i + 2], (argc - i - 1) * sizeof(char *)); + argc -= 2; + i--; + } else { + ksft_exit_fail_msg("Option --stage requires an argument\n"); + } + } + } + + luo_fd = luo_open_device(); + if (luo_fd < 0) + ksft_exit_skip("Failed to open %s (%s) device. Is LUO enabled?\n", + LUO_DEVICE, strerror(errno)); + + session = luo_retrieve_session(luo_fd, STATE_SESSION_NAME); + if (session == -ENOENT) + stage = 1; + else if (session >= 0) + stage = 2; + else + ksft_exit_fail_perror("Failed to check for state session"); + + if (expected_stage && expected_stage != stage) + ksft_exit_fail_msg("Stage mismatch: expected %d, got %d\n", + expected_stage, stage); + + if (stage == 1) + create_state_file(luo_fd, STATE_SESSION_NAME, STATE_MEMFD_TOKEN, 2); + + return test_harness_run(argc, argv); +} -- 2.53.0.1213.gd9a14994de-goog