[PATCH v2] tst-{pthread|sched}-affinity-inheritance: Only use in-mask CPUs in affinity mask.
Stefan Liebler
stli@linux.ibm.com
Fri Jan 30 08:25:12 GMT 2026
Ping
On 1/23/26 14:56, Stefan Liebler wrote:
> On s390x, the two tests are failing on a lpar with linux 6.18 booted with nosmt:
> FAIL: misc/tst-sched-affinity-inheritance
> FAIL: nptl/tst-pthread-affinity-inheritance
>
> Both tests were failing because they are claiming that the CPU affinity mask was
> not correctly inherited in the forked process/thread.
> The error already happened before forking, as the mask was set up to use
> CPUs 0-14 in set_cpu_mask(). But according to e.g. lscpu or the line
> "Cpus_allowed_list" in /proc/self/status, only the following CPUs were in mask at startup:
> 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30
> while 1, 3, 5, ... were configured, but not online.
>
> Now the test first gets the current CPU mask at startup in do_test() and
> set_cpu_mask() only selects those available CPUs.
>
> Therefore both concrete tests now have the get_my_affinity() function. This
> also allows to implement verify_my_affinity() in the common skeleton.
>
> In order to ensure that the affinity mask is really set as expected,
> verify_my_affinity() is now also called before forking a new process or
> creating a new thread.
>
> For also printing the list of mismatched CPU IDs in xor_set in
> verify_my_affinity(), the argument order of CPU_ISSET_S is now fixed.
> Furthermore we now keep iterating over all configured CPUs to print
> the list of cpucount IDs instead of iterating over the first nproc CPUs.
> ---
> nptl/tst-pthread-affinity-inheritance.c | 41 ++---------
> nptl/tst-skeleton-affinity-inheritance.c | 70 ++++++++++++++++---
> .../linux/tst-sched-affinity-inheritance.c | 40 ++---------
> 3 files changed, 73 insertions(+), 78 deletions(-)
>
> diff --git a/nptl/tst-pthread-affinity-inheritance.c b/nptl/tst-pthread-affinity-inheritance.c
> index 153fc904df..9396256ff9 100644
> --- a/nptl/tst-pthread-affinity-inheritance.c
> +++ b/nptl/tst-pthread-affinity-inheritance.c
> @@ -25,48 +25,19 @@
> #include <support/check.h>
>
> static void
> -set_my_affinity (size_t size, const cpu_set_t *set)
> +get_my_affinity (size_t size, cpu_set_t *set)
> {
> - int ret = pthread_setaffinity_np (pthread_self (), size, set);
> -
> + int ret = pthread_getaffinity_np (pthread_self (), size, set);
> if (ret != 0)
> - FAIL ("pthread_setaffinity_np returned %d (%s)", ret, strerror (ret));
> + FAIL ("pthread_getaffinity_np returned %d (%s)", ret, strerror (ret));
> }
>
> static void
> -verify_my_affinity (int nproc, int nproc_configured, size_t size,
> - const cpu_set_t *expected_set)
> +set_my_affinity (size_t size, const cpu_set_t *set)
> {
> - cpu_set_t *set = CPU_ALLOC (nproc_configured);
> - cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
> -
> - if (set == NULL || xor_set== NULL)
> - FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
> -
> - int ret = pthread_getaffinity_np (pthread_self (), size, set);
> + int ret = pthread_setaffinity_np (pthread_self (), size, set);
> if (ret != 0)
> - FAIL ("pthread_getaffinity_np returned %d (%s)", ret, strerror (ret));
> -
> - CPU_XOR_S (size, xor_set, expected_set, set);
> -
> - int cpucount = CPU_COUNT_S (size, xor_set);
> -
> - if (cpucount > 0)
> - {
> - FAIL ("Affinity mask not inherited, "
> - "following %d CPUs mismatched in the expected and actual sets: ",
> - cpucount);
> - for (int cur = 0; cur < nproc && cpucount >= 0; cur++)
> - if (CPU_ISSET_S (size, cur, xor_set))
> - {
> - printf ("%d ", cur);
> - cpucount--;
> - }
> - printf ("\n");
> - }
> -
> - CPU_FREE (set);
> - CPU_FREE (xor_set);
> + FAIL ("pthread_setaffinity_np returned %d (%s)", ret, strerror (ret));
> }
>
> #include "tst-skeleton-affinity-inheritance.c"
> diff --git a/nptl/tst-skeleton-affinity-inheritance.c b/nptl/tst-skeleton-affinity-inheritance.c
> index e1f328ae26..2d4c452f44 100644
> --- a/nptl/tst-skeleton-affinity-inheritance.c
> +++ b/nptl/tst-skeleton-affinity-inheritance.c
> @@ -45,6 +45,7 @@ struct test_param
> int nproc;
> int nproc_configured;
> cpu_set_t *set;
> + cpu_set_t *set_at_startup;
> size_t size;
> bool entry;
> };
> @@ -58,12 +59,53 @@ set_cpu_mask (struct test_param *param, bool entry)
> if (entry && cpus > 1)
> cpus--;
>
> + /* Only use CPUs which were in mask at start of the test process. */
> CPU_ZERO_S (param->size, param->set);
> - while (cpus > 0)
> - CPU_SET_S (--cpus, param->size, param->set);
> + for (int cur = 0; cpus > 0; cur++)
> + {
> + if (CPU_ISSET_S (cur, param->size, param->set_at_startup))
> + {
> + CPU_SET_S (cur, param->size, param->set);
> + cpus--;
> + }
> + }
> +
> + if (cpus != 0)
> + FAIL_EXIT1 ("Failed to add all requested CPUs to the affinity set\n");
> +}
> +
> +static void
> +verify_my_affinity (int nproc_configured, size_t size,
> + const cpu_set_t *expected_set)
> +{
> + cpu_set_t *set = CPU_ALLOC (nproc_configured);
> + cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
> +
> + if (set == NULL || xor_set == NULL)
> + FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
>
> - if (CPU_COUNT_S (param->size, param->set) == 0)
> - FAIL_EXIT1 ("Failed to add any CPUs to the affinity set\n");
> + get_my_affinity (size, set);
> +
> + CPU_XOR_S (size, xor_set, expected_set, set);
> +
> + int cpucount = CPU_COUNT_S (size, xor_set);
> +
> + if (cpucount > 0)
> + {
> + FAIL ("Affinity mask not inherited, "
> + "following %d CPUs mismatched in the expected and actual sets:\n",
> + cpucount);
> + for (int cur = 0; cpucount > 0; cur++)
> + if (CPU_ISSET_S (cur, size, xor_set))
> + {
> + printf ("%d ", cur);
> + cpucount--;
> + }
> + printf ("\n");
> + }
> +
> + CPU_FREE (set);
> + CPU_FREE (xor_set);
> }
>
> static void *
> @@ -72,8 +114,7 @@ child_test (void *arg)
> struct test_param *param = arg;
>
> printf ("%d:%d child\n", getpid (), gettid ());
> - verify_my_affinity (param->nproc, param->nproc_configured, param->size,
> - param->set);
> + verify_my_affinity (param->nproc_configured, param->size, param->set);
> return NULL;
> }
>
> @@ -91,13 +132,15 @@ do_one_test (void *arg)
> child = do_one_test;
> set_cpu_mask (param, true);
> set_my_affinity (param->size, param->set);
> + /* Ensure that the affinity mask is really set as expected before forking
> + a new process or creating a new thread. */
> + verify_my_affinity (param->nproc_configured, param->size, param->set);
> param->entry = false;
> }
> else
> {
> /* Verification for the first level. */
> - verify_my_affinity (param->nproc, param->nproc_configured, param->size,
> - param->set);
> + verify_my_affinity (param->nproc_configured, param->size, param->set);
>
> /* Launch the second level test, launching CHILD_TEST as a subprocess and
> then as a subthread. Use a different mask to see if it gets
> @@ -143,16 +186,25 @@ do_test (void)
> .nproc = num_cpus,
> .nproc_configured = num_configured_cpus,
> .set = CPU_ALLOC (num_configured_cpus),
> + .set_at_startup = CPU_ALLOC (num_configured_cpus),
> .size = CPU_ALLOC_SIZE (num_configured_cpus),
> .entry = true,
> };
>
> if (param.set == NULL)
> - FAIL_EXIT1 ("error: CPU_ALLOC (%d) failed\n", num_cpus);
> + FAIL_EXIT1 ("error: CPU_ALLOC (%d) for param.set failed\n",
> + num_configured_cpus);
> + if (param.set_at_startup == NULL)
> + FAIL_EXIT1 ("error: CPU_ALLOC (%d) for param.set_at_startup failed\n",
> + num_configured_cpus);
> +
> + /* Get a list of all available CPUs for this test. */
> + get_my_affinity (param.size, param.set_at_startup);
>
> do_one_test (¶m);
>
> CPU_FREE (param.set);
> + CPU_FREE (param.set_at_startup);
>
> return 0;
> }
> diff --git a/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c b/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
> index 8a42d275fc..09e17cbdec 100644
> --- a/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
> +++ b/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
> @@ -25,48 +25,20 @@
> #include <support/check.h>
>
> static void
> -set_my_affinity (size_t size, const cpu_set_t *set)
> +get_my_affinity (size_t size, cpu_set_t *set)
> {
> - int ret = sched_setaffinity (0, size, set);
> -
> + int ret = sched_getaffinity (0, size, set);
> if (ret != 0)
> - FAIL ("sched_setaffinity returned %d (%s)", ret, strerror (ret));
> + FAIL ("sched_getaffinity returned %d (%s)", ret, strerror (ret));
> }
>
> static void
> -verify_my_affinity (int nproc, int nproc_configured, size_t size,
> - const cpu_set_t *expected_set)
> +set_my_affinity (size_t size, const cpu_set_t *set)
> {
> - cpu_set_t *set = CPU_ALLOC (nproc_configured);
> - cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
> -
> - if (set == NULL || xor_set== NULL)
> - FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
> + int ret = sched_setaffinity (0, size, set);
>
> - int ret = sched_getaffinity (0, size, set);
> if (ret != 0)
> - FAIL ("sched_getaffinity returned %d (%s)", ret, strerror (ret));
> -
> - CPU_XOR_S (size, xor_set, expected_set, set);
> -
> - int cpucount = CPU_COUNT_S (size, xor_set);
> -
> - if (cpucount > 0)
> - {
> - FAIL ("Affinity mask not inherited, "
> - "following %d CPUs mismatched in the expected and actual sets:\n",
> - cpucount);
> - for (int cur = 0; cur < nproc && cpucount >= 0; cur++)
> - if (CPU_ISSET_S (size, cur, xor_set))
> - {
> - printf ("%d ", cur);
> - cpucount--;
> - }
> - printf ("\n");
> - }
> -
> - CPU_FREE (set);
> - CPU_FREE (xor_set);
> + FAIL ("sched_setaffinity returned %d (%s)", ret, strerror (ret));
> }
>
> #include <nptl/tst-skeleton-affinity-inheritance.c>
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