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Date: Tue, 30 Apr 2024 14:57:05 +0200
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Subject: Re: [PATCH 3/4] mm/ksm: rename mm_slot_cache to ksm_slot_cache
To: alexs@kernel.org, Andrew Morton <akpm@linux-foundation.org>,
 linux-mm@kvack.org, linux-kernel@vger.kernel.org, willy@infradead.org,
 izik.eidus@ravellosystems.com
References: <20240428100619.3332036-1-alexs@kernel.org>
 <20240428100619.3332036-3-alexs@kernel.org>
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From: David Hildenbrand <david@redhat.com>
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In-Reply-To: <20240428100619.3332036-3-alexs@kernel.org>
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On 28.04.24 12:06, alexs@kernel.org wrote:
> From: "Alex Shi (tencent)" <alexs@kernel.org>
> 
> To distinguish ksm_mm_slot and mm_slot for better code readability,
> rename mm_slot_cache as ksm_slot_cache. No function change.
> 
> Signed-off-by: Alex Shi (tencent) <alexs@kernel.org>
> Cc: David Hildenbrand <david@redhat.com>
> ---
>   mm/ksm.c | 18 +++++++++---------
>   1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 6efa33c48381..22d2132f83a4 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -247,7 +247,7 @@ static struct ksm_scan ksm_scan = {
>   
>   static struct kmem_cache *rmap_item_cache;
>   static struct kmem_cache *stable_node_cache;
> -static struct kmem_cache *mm_slot_cache;
> +static struct kmem_cache *ksm_slot_cache;
>   
>   /* Default number of pages to scan per batch */
>   #define DEFAULT_PAGES_TO_SCAN 100
> @@ -502,8 +502,8 @@ static int __init ksm_slab_init(void)
>   	if (!stable_node_cache)
>   		goto out_free1;
>   
> -	mm_slot_cache = KSM_KMEM_CACHE(ksm_mm_slot, 0);
> -	if (!mm_slot_cache)
> +	ksm_slot_cache = KSM_KMEM_CACHE(ksm_mm_slot, 0);
> +	if (!ksm_slot_cache)
>   		goto out_free2;
>   
>   	return 0;
> @@ -518,10 +518,10 @@ static int __init ksm_slab_init(void)
>   
>   static void __init ksm_slab_free(void)
>   {
> -	kmem_cache_destroy(mm_slot_cache);
> +	kmem_cache_destroy(ksm_slot_cache);
>   	kmem_cache_destroy(stable_node_cache);
>   	kmem_cache_destroy(rmap_item_cache);
> -	mm_slot_cache = NULL;
> +	ksm_slot_cache = NULL;
>   }
>   
>   static __always_inline bool is_stable_node_chain(struct ksm_stable_node *chain)
> @@ -1244,7 +1244,7 @@ static int unmerge_and_remove_all_rmap_items(void)
>   			list_del(&ksm_slot->slot.mm_node);
>   			spin_unlock(&ksm_mmlist_lock);
>   
> -			mm_slot_free(mm_slot_cache, ksm_slot);
> +			mm_slot_free(ksm_slot_cache, ksm_slot);
>   			clear_bit(MMF_VM_MERGEABLE, &mm->flags);
>   			clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
>   			mmdrop(mm);
> @@ -2713,7 +2713,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
>   		list_del(&ksm_slot->slot.mm_node);
>   		spin_unlock(&ksm_mmlist_lock);
>   
> -		mm_slot_free(mm_slot_cache, ksm_slot);
> +		mm_slot_free(ksm_slot_cache, ksm_slot);
>   		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
>   		clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
>   		mmap_read_unlock(mm);
> @@ -2972,7 +2972,7 @@ int __ksm_enter(struct mm_struct *mm)
>   	struct mm_slot *slot;
>   	int needs_wakeup;
>   
> -	ksm_slot = mm_slot_alloc(mm_slot_cache);
> +	ksm_slot = mm_slot_alloc(ksm_slot_cache);

Similarly, this makes the code more confusion. The pattern in khugepaged 
is similarly:

mm_slot = mm_slot_alloc(mm_slot_cache);

I don't think we want these renamings.

E.g., "ksm_mm_slot_cache" might be a bit better than "mm_slot_cache". 
But then, we are in KSM code ... so I don't really see an improvement.

-- 
Cheers,

David / dhildenb