Re: [PATCH] mm/damon/ops-common: factor out damon_putback_folio_list()

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Removal of `struct folio *folio;` declaration causes a compilation failure in `damon_migrate_folio_list()`.
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--- Patch [1]: [PATCH] mm/damon/ops-common: factor out damon_putback_folio_list() ---
commit b95b21fa4d0d8990d47609474f8cee2aa7d640e1
Author: Li Youhong <[email protected]>

mm/damon/ops-common: factor out damon_putback_folio_list()

This commit factors out the duplicated putback loop in
damon_migrate_folio_list() and damon_migrate_pages() into a new
damon_putback_folio_list() helper. The commit notes state this removes
the need for the local folio variable.

Link: https://lore.kernel.org/all/[email protected]/

> diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
> index fbda70d8ea4d0..f9cfd35bee722 100644
> --- a/mm/damon/ops-common.c
> +++ b/mm/damon/ops-common.c
[ ... ]
>  static unsigned int damon_migrate_folio_list(struct list_head *folio_list,
>  						struct pglist_data *pgdat,
>  						int target_nid)
>  {
>  	unsigned int nr_migrated = 0;
> -	struct folio *folio;
>  	LIST_HEAD(ret_folios);
>  	LIST_HEAD(migrate_folios);

[Severity: Low]
The commit message notes that removing the folio variable here won't cause
a build failure. However, does damon_migrate_folio_list() still use the
folio variable in its first while-loop?

Looking at the remaining code in damon_migrate_folio_list():

	while (!list_empty(folio_list)) {
		cond_resched();

		folio = lru_to_folio(folio_list);
		list_del(&folio->lru);

		if (!folio_trylock(folio))
			goto keep;

Will this cause an undeclared identifier compilation error since the variable
was removed from the function scope but not re-declared locally inside this
loop block?

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1