Nit on subject, function -> functions.
On Mon, Jul 07, 2025 at 04:23:16PM +0200, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
>
> Add huge_zero_page_shrinker_init() and huge_zero_page_shrinker_exit().
> As shrinker will not be needed when static PMD zero page is enabled,
> these two functions can be a no-op.
>
> This is a preparation patch for static PMD zero page. No functional
> changes.
This is nitty stuff, but I think this is a little unclear, maybe something
like:
We will soon be determining whether to use a shrinker depending on
whether a static PMD zero page is available, therefore abstract out
shrink initialisation and teardown such that we can more easily
handle both the shrinker and static PMD zero page cases.
>
> Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
Other than nits, this LGTM, so with those addressed:
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
> ---
> mm/huge_memory.c | 38 +++++++++++++++++++++++++++-----------
> 1 file changed, 27 insertions(+), 11 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index d3e66136e41a..101b67ab2eb6 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -289,6 +289,24 @@ static unsigned long shrink_huge_zero_page_scan(struct shrinker *shrink,
> }
>
> static struct shrinker *huge_zero_page_shrinker;
> +static int huge_zero_page_shrinker_init(void)
> +{
> + huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
> + if (!huge_zero_page_shrinker)
> + return -ENOMEM;
> +
> + huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
> + huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
> + shrinker_register(huge_zero_page_shrinker);
> + return 0;
> +}
> +
> +static void huge_zero_page_shrinker_exit(void)
> +{
> + shrinker_free(huge_zero_page_shrinker);
> + return;
> +}
> +
>
> #ifdef CONFIG_SYSFS
> static ssize_t enabled_show(struct kobject *kobj,
> @@ -850,33 +868,31 @@ static inline void hugepage_exit_sysfs(struct kobject *hugepage_kobj)
>
> static int __init thp_shrinker_init(void)
> {
> - huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
> - if (!huge_zero_page_shrinker)
> - return -ENOMEM;
> + int ret = 0;
Kinda no point in initialising to zero, unless...
>
> deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
> SHRINKER_MEMCG_AWARE |
> SHRINKER_NONSLAB,
> "thp-deferred_split");
> - if (!deferred_split_shrinker) {
> - shrinker_free(huge_zero_page_shrinker);
> + if (!deferred_split_shrinker)
> return -ENOMEM;
> - }
> -
> - huge_zero_page_shrinker->count_objects = shrink_huge_zero_page_count;
> - huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
> - shrinker_register(huge_zero_page_shrinker);
>
> deferred_split_shrinker->count_objects = deferred_split_count;
> deferred_split_shrinker->scan_objects = deferred_split_scan;
> shrinker_register(deferred_split_shrinker);
>
> + ret = huge_zero_page_shrinker_init();
> + if (ret) {
> + shrinker_free(deferred_split_shrinker);
> + return ret;
> + }
... you change this to:
if (ret)
shrinker_free(deferred_split_shrinker);
return ret;
But it's not a big deal. Maybe I'd rename ret -> err if you keep things as
they are (but don't init to 0).
> +
> return 0;
> }
>
> static void __init thp_shrinker_exit(void)
> {
> - shrinker_free(huge_zero_page_shrinker);
> + huge_zero_page_shrinker_exit();
> shrinker_free(deferred_split_shrinker);
> }
>
> --
> 2.49.0
>
