Re: [PATCH v2 1/2] mm/mm_slot.h: add a helper function mm_slot_remove

[Nico Pache]

On Mon, Jul 13, 2026 at 12:37 AM <xu.xin16@xxxxxxxxxx> wrote:
>
> From: xu xin <xu.xin16@xxxxxxxxxx>
>
> Both THP and KSM manage per-mm scanning slots using the mm_slot
> structure. The slot is kept in a hash table and a list, and removal from
> both containers requires the same two operations: hash_del() and
> list_del().
>
> Introduce mm_slot_remove() to abstract the common hash_del() + list_del()
> sequence used in both khugepaged and KSM.
>
> No functional change is intended.
>
> Signed-off-by: xu xin <xu.xin16@xxxxxxxxxx>

LGTM!

Reviewed-by: Nico Pache <npache@xxxxxxxxxx>

> ---
>  mm/khugepaged.c | 6 ++----
>  mm/ksm.c        | 9 +++------
>  mm/mm_slot.h    | 5 +++++
>  3 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 58e14d1543ec..5f6eb1bd9a67 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -606,8 +606,7 @@ void __khugepaged_exit(struct mm_struct *mm)
>         spin_lock(&khugepaged_mm_lock);
>         slot = mm_slot_lookup(mm_slots_hash, mm);
>         if (slot && khugepaged_scan.mm_slot != slot) {
> -               hash_del(&slot->hash);
> -               list_del(&slot->mm_node);
> +               mm_slot_remove(slot);
>                 free = 1;
>         }
>         spin_unlock(&khugepaged_mm_lock);
> @@ -1802,8 +1801,7 @@ static void collect_mm_slot(struct mm_slot *slot)
>
>         if (collapse_test_exit(mm)) {
>                 /* free mm_slot */
> -               hash_del(&slot->hash);
> -               list_del(&slot->mm_node);
> +               mm_slot_remove(slot);
>
>                 /*
>                  * Not strictly needed because the mm exited already.
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 2791ce5bd44b..443dab513da6 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -1257,8 +1257,7 @@ static int unmerge_and_remove_all_rmap_items(void)
>                                   struct mm_slot, mm_node);
>                 ksm_scan.mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot);
>                 if (ksm_test_exit(mm)) {
> -                       hash_del(&mm_slot->slot.hash);
> -                       list_del(&mm_slot->slot.mm_node);
> +                       mm_slot_remove(&mm_slot->slot);
>                         spin_unlock(&ksm_mmlist_lock);
>
>                         mm_slot_free(mm_slot_cache, mm_slot);
> @@ -2772,8 +2771,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
>                  * or when all VM_MERGEABLE areas have been unmapped (and
>                  * mmap_lock then protects against race with MADV_MERGEABLE).
>                  */
> -               hash_del(&mm_slot->slot.hash);
> -               list_del(&mm_slot->slot.mm_node);
> +               mm_slot_remove(&mm_slot->slot);
>                 spin_unlock(&ksm_mmlist_lock);
>
>                 mm_slot_free(mm_slot_cache, mm_slot);
> @@ -3116,8 +3114,7 @@ void __ksm_exit(struct mm_struct *mm)
>         if (ksm_scan.mm_slot == mm_slot)
>                 goto unlock;
>         if (!mm_slot->rmap_list) {
> -               hash_del(&slot->hash);
> -               list_del(&slot->mm_node);
> +               mm_slot_remove(slot);
>                 easy_to_free = 1;
>         } else {
>                 list_move(&slot->mm_node,
> diff --git a/mm/mm_slot.h b/mm/mm_slot.h
> index 83f18ed1c4bd..5de3e91d86b4 100644
> --- a/mm/mm_slot.h
> +++ b/mm/mm_slot.h
> @@ -52,4 +52,9 @@ static inline void mm_slot_free(struct kmem_cache *cache, void *objp)
>         hash_add(_hashtable, &_mm_slot->hash, (unsigned long)_mm);             \
>  })
>
> +static inline void mm_slot_remove(struct mm_slot *slot)
> +{
> +       hash_del(&slot->hash);
> +       list_del(&slot->mm_node);
> +}
>  #endif /* _LINUX_MM_SLOT_H */
> --
> 2.25.1
>