[LTP] memcg/memcontrol05: add cgroup v2 task migration charge accounting test

[linuxtestproject.agent@gmail.com]

Hi Pavithra,

On Aug 12, 2026, Pavithra wrote:
> memcg/memcontrol05: add cgroup v2 task migration charge accounting test

> +#define ALLOC_SIZE	MB(60)
> +#define ALLOC_SIZE2	MB(20)
> +#define MIN_MEM_AVAIL	80

[Medium] Could MIN_MEM_AVAIL include headroom above the two mappings? The
worker keeps both mappings resident simultaneously, so a host with exactly
80 MiB available passes the framework check but still needs memory for page
tables and other process and kernel allocations. The worker can be OOM-killed
while touching the mappings, producing a timeout or TBROK instead of testing
charge accounting.

> +	SAFE_CG_SCANF(group_b, "memory.current", "%ld", &after_migrate);
> +	TST_EXP_EXPR(after_migrate <= baseline_b + (long)MB(4),
> +		     "group_b memory.current (%ld) not increased after migration (baseline=%ld)",
> +		     after_migrate, baseline_b);

[Medium] Could this also read and verify group_a/memory.current after the
migration? The stated invariant is that existing charges remain pinned to
group_a, but this checks only that group_b did not gain them. A regression
that drops those charges during migration leaves group_b within the allowed
range and reports TPASS despite violating the invariant.

Verdict - Needs revision

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