[LTP] memcontrol: Add bind_to_current_cpu() helper

[linuxtestproject.agent@gmail.com]

Hi Wei,

On Wed Sep 30 03:53:14 2026 +0000, Wei Gao via ltp wrote:
> memcontrol: Add bind_to_current_cpu() helper

--- [PATCH 1/2] ---

> Add bind_to_current_cpu() to memcontrol_common.h to allow memcg tests
> to bind the test process to a single CPU.

The commit message only restates what changed. Explain why memcg tests
need to bind to a single CPU (e.g. to prevent multi-CPU per-CPU memcg stock
charge accumulation from causing reclaim variance in hierarchical tests).

> +static inline void bind_to_current_cpu(void)
> +{
> +	int cpu = sched_getcpu();
> +	size_t mask_size;
> +	cpu_set_t *mask;

Include <sched.h> in memcontrol_common.h. The function uses sched_getcpu(),
cpu_set_t, CPU_ALLOC(), and sched_setaffinity(), but currently relies on
indirect inclusion via tst_test.h.

Verdict - Needs revision

Pre-existing issues:
- memcontrol03.c:209: sleep(1) is used in a polling loop. Polling loops
  should use exponential backoff or checkpoint synchronization.
- memcontrol03.c:241, memcontrol04.c:240: fd validity is checked with
  fd > -1 instead of the LTP convention fd != -1.

---
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