[Devel] [PATCH hci-8.1 v3 0/2] sched: Fix incorrect nproc report inside CT

[Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>]

We observed weird nproc behavior - it reported 64 CPUs
no matter what the CT limits were or how many CPUs the host
actually had.

nproc code uses sched_getaffinity syscall under the hood[1].
It appears that this syscall returned complete nonsence when
called from VE - we ignored both num_online_vcpus and
cgroup cpuset limitations.

Now it is fixed and a new selftest is added.

[1]: https://github.com/coreutils/gnulib/blob/master/lib/nproc.c#L144
https://virtuozzo.atlassian.net/browse/VSTOR-141682

Signed-off-by: Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>
---
Changes in v3:
- Patch 1: num_online_vcpus() -> task_nr_cpus(p)
- Patch 2: updated a comment and moved CPU check in setup fixture to the top.
- Link to v2: http://lore.virtuozzo.com/20261028-ct-invalid-nrpoc-v2-0-968fe985ce27@virtuozzo.com

Changes in v2:
- Updated vCPU logic in patch 1. Now we don't return actual
  cpumask, insted first min(vcpu, count(mask)) bits are set.
  This is closer to the real CT resources.
- Patch 2: adjusted logic and added one more test.
- Link to v1: http://lore.virtuozzo.com/20261027-ct-invalid-nrpoc-v1-0-48727c3afe16@virtuozzo.com

---
Vladimir Riabchun (2):
      sched: Fix sched_getaffinity syscall
      selftests: ve: Test sched_getaffinity in VE

 kernel/sched/syscalls.c                            |  18 +-
 tools/testing/selftests/ve/.gitignore              |   1 +
 tools/testing/selftests/ve/Makefile                |   1 +
 .../selftests/ve/ve_sched_getaffinity_test.c       | 211 +++++++++++++++++++++
 4 files changed, 226 insertions(+), 5 deletions(-)
---
base-commit: b499efa17aa9fb8f20512d1831d1cb61b22e60d3
change-id: 20261027-ct-invalid-nrpoc-f183b3ba691d

Best regards,
--  
Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>

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