Re: [PATCH mm-new 1/1] mm/khugepaged: Factor out common logic in [scan,alloc]_sleep_millisecs_store()

Lorenzo Stoakes
2025-10-20T13:53:53Z

On Mon, Oct 20, 2025 at 07:53:50PM +0800, Leon Hwang wrote:
> Both scan_sleep_millisecs_store() and alloc_sleep_millisecs_store()
> perform the same operations: parse the input value, update their
> respective sleep interval, reset khugepaged_sleep_expire, and wake up
> the khugepaged thread.
>
> Factor out this duplicated logic into a helper function
> __sleep_millisecs_store(), and simplify both store functions.
>
> No functional change intended.
>
> Signed-off-by: Leon Hwang <leon.hwang@linux.dev>

Thanks this is a decent cleanup, with the nit(s0 below addressed LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
> mm/khugepaged.c | 29 ++++++++++++++---------------
> 1 file changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 0341c3d13e9e..0b7915015e9e 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -129,9 +129,8 @@ static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
> return sysfs_emit(buf, "%u\n", khugepaged_scan_sleep_millisecs);
> }
>
> -static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
> - struct kobj_attribute *attr,
> - const char *buf, size_t count)
> +static ssize_t __sleep_millisecs_store(const char *buf, size_t count,
> + unsigned int *millisecs)
> {
> unsigned int msecs;
> int err;
> @@ -140,12 +139,21 @@ static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
> if (err)
> return -EINVAL;
>
> - khugepaged_scan_sleep_millisecs = msecs;
> + *millisecs = msecs;
> khugepaged_sleep_expire = 0;
> wake_up_interruptible(&khugepaged_wait);
>
> return count;
> }
> +
> +static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + unsigned int *millisecs = &khugepaged_scan_sleep_millisecs;
> +
> + return __sleep_millisecs_store(buf, count, millisecs);

I think this'd be much clearer as:

return __sleep_millisecs_store(buf, count, &khugepaged_alloc_scan_millisecs);

> +}
> static struct kobj_attribute scan_sleep_millisecs_attr =
> __ATTR_RW(scan_sleep_millisecs);
>
> @@ -160,18 +168,9 @@ static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
> struct kobj_attribute *attr,
> const char *buf, size_t count)
> {
> - unsigned int msecs;
> - int err;
> -
> - err = kstrtouint(buf, 10, &msecs);
> - if (err)
> - return -EINVAL;
> + unsigned int *millisecs = &khugepaged_alloc_sleep_millisecs;
>
> - khugepaged_alloc_sleep_millisecs = msecs;
> - khugepaged_sleep_expire = 0;
> - wake_up_interruptible(&khugepaged_wait);
> -
> - return count;
> + return __sleep_millisecs_store(buf, count, millisecs);
> }

I think this'd be much clearer as:

return __sleep_millisecs_store(buf, count, &khugepaged_alloc_sleep_millisecs);

> static struct kobj_attribute alloc_sleep_millisecs_attr =
> __ATTR_RW(alloc_sleep_millisecs);
> --
> 2.51.0
>