Re: [PATCH v4 11/13] selftests/liveupdate: Test session and file limit removal

[Pratyush Yadav <pratyush@kernel.org>]

On Sat, May 30 2026, Pasha Tatashin wrote:

> With the removal of static limits on the number of sessions and files per
> session, the orchestrator now uses dynamic allocation.
>
> Add new test cases to verify that the system can handle a large number of
> sessions and files. These tests ensure that the dynamic block allocation
> and reuse logic for session metadata and outgoing files work correctly
> beyond the previous static limits.
>
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>

Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org>

> ---
>  .../testing/selftests/liveupdate/liveupdate.c | 75 +++++++++++++++++++
>  .../selftests/liveupdate/luo_test_utils.c     | 24 ++++++
>  .../selftests/liveupdate/luo_test_utils.h     |  2 +
>  3 files changed, 101 insertions(+)
>
> diff --git a/tools/testing/selftests/liveupdate/liveupdate.c b/tools/testing/selftests/liveupdate/liveupdate.c
> index c7d94b9181e1..502fb3567e38 100644
> --- a/tools/testing/selftests/liveupdate/liveupdate.c
> +++ b/tools/testing/selftests/liveupdate/liveupdate.c
> @@ -26,6 +26,7 @@
>  
>  #include <linux/liveupdate.h>
>  
> +#include "luo_test_utils.h"
>  #include "../kselftest.h"
>  #include "../kselftest_harness.h"
>  
> @@ -499,4 +500,78 @@ TEST_F(liveupdate_device, get_session_name_max_length)
>  	ASSERT_EQ(close(session_fd), 0);
>  }
>  
> +/*
> + * Test Case: Manage Many Sessions
> + *
> + * Verifies that a large number of sessions can be created and then
> + * destroyed during normal system operation. This specifically tests the
> + * dynamic block allocation and reuse logic for session metadata management
> + * without preserving any files.
> + */
> +TEST_F(liveupdate_device, preserve_many_sessions)
> +{
> +#define MANY_SESSIONS 2000
> +	int session_fds[MANY_SESSIONS];
> +	int ret, i;
> +
> +	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> +	if (self->fd1 < 0 && errno == ENOENT)
> +		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> +	ASSERT_GE(self->fd1, 0);
> +
> +	ret = luo_ensure_nofile_limit(MANY_SESSIONS);
> +	if (ret == -EPERM)
> +		SKIP(return, "Insufficient privileges to set RLIMIT_NOFILE");
> +	ASSERT_EQ(ret, 0);
> +
> +	for (i = 0; i < MANY_SESSIONS; i++) {
> +		char name[64];
> +
> +		snprintf(name, sizeof(name), "many-session-%d", i);
> +		session_fds[i] = create_session(self->fd1, name);
> +		ASSERT_GE(session_fds[i], 0);
> +	}
> +
> +	for (i = 0; i < MANY_SESSIONS; i++)
> +		ASSERT_EQ(close(session_fds[i]), 0);
> +}
> +
> +/*
> + * Test Case: Preserve Many Files
> + *
> + * Verifies that a large number of files can be preserved in a single session
> + * and then destroyed during normal system operation. This tests the dynamic
> + * block allocation and management for outgoing files.
> + */
> +TEST_F(liveupdate_device, preserve_many_files)
> +{
> +#define MANY_FILES 500
> +	int mem_fds[MANY_FILES];
> +	int session_fd, ret, i;
> +
> +	self->fd1 = open(LIVEUPDATE_DEV, O_RDWR);
> +	if (self->fd1 < 0 && errno == ENOENT)
> +		SKIP(return, "%s does not exist", LIVEUPDATE_DEV);
> +	ASSERT_GE(self->fd1, 0);
> +
> +	session_fd = create_session(self->fd1, "many-files-test");
> +	ASSERT_GE(session_fd, 0);
> +
> +	ret = luo_ensure_nofile_limit(MANY_FILES + 10);
> +	if (ret == -EPERM)
> +		SKIP(return, "Insufficient privileges to set RLIMIT_NOFILE");
> +	ASSERT_EQ(ret, 0);
> +
> +	for (i = 0; i < MANY_FILES; i++) {
> +		mem_fds[i] = memfd_create("test-memfd", 0);
> +		ASSERT_GE(mem_fds[i], 0);
> +		ASSERT_EQ(preserve_fd(session_fd, mem_fds[i], i), 0);
> +	}
> +
> +	for (i = 0; i < MANY_FILES; i++)
> +		ASSERT_EQ(close(mem_fds[i]), 0);
> +
> +	ASSERT_EQ(close(session_fd), 0);
> +}
> +
>  TEST_HARNESS_MAIN
> diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.c b/tools/testing/selftests/liveupdate/luo_test_utils.c
> index 3c8721c505df..333a3530051b 100644
> --- a/tools/testing/selftests/liveupdate/luo_test_utils.c
> +++ b/tools/testing/selftests/liveupdate/luo_test_utils.c
> @@ -17,6 +17,7 @@
>  #include <sys/syscall.h>
>  #include <sys/mman.h>
>  #include <sys/types.h>
> +#include <sys/resource.h>
>  #include <sys/stat.h>
>  #include <errno.h>
>  #include <stdarg.h>
> @@ -28,6 +29,29 @@ int luo_open_device(void)
>  	return open(LUO_DEVICE, O_RDWR);
>  }
>  
> +int luo_ensure_nofile_limit(long min_limit)
> +{
> +	struct rlimit hl;
> +
> +	/* Allow to extra files to be used by test itself */
> +	min_limit += 32;
> +
> +	if (getrlimit(RLIMIT_NOFILE, &hl) < 0)
> +		return -errno;
> +
> +	if (hl.rlim_cur >= min_limit)
> +		return 0;
> +
> +	hl.rlim_cur = min_limit;
> +	if (hl.rlim_cur > hl.rlim_max)
> +		hl.rlim_max = hl.rlim_cur;
> +
> +	if (setrlimit(RLIMIT_NOFILE, &hl) < 0)
> +		return -errno;
> +
> +	return 0;
> +}
> +
>  int luo_create_session(int luo_fd, const char *name)
>  {
>  	struct liveupdate_ioctl_create_session arg = { .size = sizeof(arg) };
> diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.h b/tools/testing/selftests/liveupdate/luo_test_utils.h
> index 90099bf49577..6a0d85386613 100644
> --- a/tools/testing/selftests/liveupdate/luo_test_utils.h
> +++ b/tools/testing/selftests/liveupdate/luo_test_utils.h
> @@ -26,6 +26,8 @@ int luo_create_session(int luo_fd, const char *name);
>  int luo_retrieve_session(int luo_fd, const char *name);
>  int luo_session_finish(int session_fd);
>  
> +int luo_ensure_nofile_limit(long min_limit);
> +
>  int create_and_preserve_memfd(int session_fd, int token, const char *data);
>  int restore_and_verify_memfd(int session_fd, int token, const char *expected_data);

-- 
Regards,
Pratyush Yadav