Re: [PATCH] maple_tree: remove the parameter entry of mas_preallocate

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* Vernon Yang <vernon2gm@xxxxxxxxx> [230110 10:42]:
> The parameter entry of mas_preallocate is not used, so drop it.

This parameter was meant to reduce the allocations needed to store a
given value.  Since NULLs behave differently than actual values (NULLs
are combined), the value being stored was going to be used.

Since the fix to remove GFP_ZERO from the allocator of the maple tree
nodes [1], this may no longer be a worth while optimization.

[1] https://lore.kernel.org/all/20230105160427.2988454-1-Liam.Howlett@xxxxxxxxxx/


Acked-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>

> 
> Signed-off-by: Vernon Yang <vernon2gm@xxxxxxxxx>
> ---
>  include/linux/maple_tree.h       |  2 +-
>  lib/maple_tree.c                 |  3 +--
>  mm/mmap.c                        | 16 ++++++++--------
>  mm/nommu.c                       |  8 ++++----
>  tools/testing/radix-tree/maple.c | 32 ++++++++++++++++----------------
>  5 files changed, 30 insertions(+), 31 deletions(-)
> 
> diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
> index e594db58a0f1..a0d43087f27a 100644
> --- a/include/linux/maple_tree.h
> +++ b/include/linux/maple_tree.h
> @@ -456,7 +456,7 @@ int mas_store_gfp(struct ma_state *mas, void *entry, gfp_t gfp);
>  void mas_store_prealloc(struct ma_state *mas, void *entry);
>  void *mas_find(struct ma_state *mas, unsigned long max);
>  void *mas_find_rev(struct ma_state *mas, unsigned long min);
> -int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp);
> +int mas_preallocate(struct ma_state *mas, gfp_t gfp);
>  bool mas_is_err(struct ma_state *mas);
>  
>  bool mas_nomem(struct ma_state *mas, gfp_t gfp);
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 69be9d3db0c8..96fb4b416697 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5712,12 +5712,11 @@ EXPORT_SYMBOL_GPL(mas_store_prealloc);
>  /**
>   * mas_preallocate() - Preallocate enough nodes for a store operation
>   * @mas: The maple state
> - * @entry: The entry that will be stored
>   * @gfp: The GFP_FLAGS to use for allocations.
>   *
>   * Return: 0 on success, -ENOMEM if memory could not be allocated.
>   */
> -int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
> +int mas_preallocate(struct ma_state *mas, gfp_t gfp)
>  {
>  	int ret;
>  
> diff --git a/mm/mmap.c b/mm/mmap.c
> index e06f9ae34ff8..64bdd38e8d8e 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -472,7 +472,7 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
>  	MA_STATE(mas, &mm->mm_mt, 0, 0);
>  	struct address_space *mapping = NULL;
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(&mas, GFP_KERNEL))
>  		return -ENOMEM;
>  
>  	if (vma->vm_file) {
> @@ -538,7 +538,7 @@ inline int vma_expand(struct ma_state *mas, struct vm_area_struct *vma,
>  	/* Only handles expanding */
>  	VM_BUG_ON(vma->vm_start < start || vma->vm_end > end);
>  
> -	if (mas_preallocate(mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(mas, GFP_KERNEL))
>  		goto nomem;
>  
>  	vma_adjust_trans_huge(vma, start, end, 0);
> @@ -712,7 +712,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
>  		}
>  	}
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(&mas, GFP_KERNEL))
>  		return -ENOMEM;
>  
>  	vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
> @@ -1934,7 +1934,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
>  		/* Check that both stack segments have the same anon_vma? */
>  	}
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(&mas, GFP_KERNEL))
>  		return -ENOMEM;
>  
>  	/* We must make sure the anon_vma is allocated. */
> @@ -2015,7 +2015,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address)
>  			return -ENOMEM;
>  	}
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(&mas, GFP_KERNEL))
>  		return -ENOMEM;
>  
>  	/* We must make sure the anon_vma is allocated. */
> @@ -2307,7 +2307,7 @@ do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
>  	mt_init_flags(&mt_detach, MT_FLAGS_LOCK_EXTERN);
>  	mt_set_external_lock(&mt_detach, &mm->mmap_lock);
>  
> -	if (mas_preallocate(mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(mas, GFP_KERNEL))
>  		return -ENOMEM;
>  
>  	mas->last = end - 1;
> @@ -2676,7 +2676,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
>  			goto free_vma;
>  	}
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL)) {
> +	if (mas_preallocate(&mas, GFP_KERNEL)) {
>  		error = -ENOMEM;
>  		if (file)
>  			goto close_and_free_vma;
> @@ -2949,7 +2949,7 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
>  	    can_vma_merge_after(vma, flags, NULL, NULL,
>  				addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
>  		mas_set_range(mas, vma->vm_start, addr + len - 1);
> -		if (mas_preallocate(mas, vma, GFP_KERNEL))
> +		if (mas_preallocate(mas, GFP_KERNEL))
>  			goto unacct_fail;
>  
>  		vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0);
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 214c70e1d059..0befa4060aea 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -602,7 +602,7 @@ static int add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
>  {
>  	MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_end);
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL)) {
> +	if (mas_preallocate(&mas, GFP_KERNEL)) {
>  		pr_warn("Allocation of vma tree for process %d failed\n",
>  		       current->pid);
>  		return -ENOMEM;
> @@ -633,7 +633,7 @@ static int delete_vma_from_mm(struct vm_area_struct *vma)
>  {
>  	MA_STATE(mas, &vma->vm_mm->mm_mt, 0, 0);
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL)) {
> +	if (mas_preallocate(&mas, GFP_KERNEL)) {
>  		pr_warn("Allocation of vma tree for process %d failed\n",
>  		       current->pid);
>  		return -ENOMEM;
> @@ -1081,7 +1081,7 @@ unsigned long do_mmap(struct file *file,
>  	if (!vma)
>  		goto error_getting_vma;
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL))
> +	if (mas_preallocate(&mas, GFP_KERNEL))
>  		goto error_maple_preallocate;
>  
>  	region->vm_usage = 1;
> @@ -1358,7 +1358,7 @@ int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
>  	if (!new)
>  		goto err_vma_dup;
>  
> -	if (mas_preallocate(&mas, vma, GFP_KERNEL)) {
> +	if (mas_preallocate(&mas, GFP_KERNEL)) {
>  		pr_warn("Allocation of vma tree for process %d failed\n",
>  			current->pid);
>  		goto err_mas_preallocate;
> diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
> index 81fa7ec2e66a..8170ef39d8c4 100644
> --- a/tools/testing/radix-tree/maple.c
> +++ b/tools/testing/radix-tree/maple.c
> @@ -35342,7 +35342,7 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	for (i = 0; i <= max; i++)
>  		mtree_test_store_range(mt, i * 10, i * 10 + 5, &i);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35351,18 +35351,18 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	allocated = mas_allocated(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
>  	MT_BUG_ON(mt, allocated != 1 + height * 3);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	mas_destroy(&mas);
>  	allocated = mas_allocated(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35370,25 +35370,25 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	mn = mas_pop_node(&mas);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != allocated - 1);
>  	ma_free_rcu(mn);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	mas_destroy(&mas);
>  	allocated = mas_allocated(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
>  	MT_BUG_ON(mt, allocated != 1 + height * 3);
>  	mn = mas_pop_node(&mas);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != allocated - 1);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	mas_destroy(&mas);
>  	allocated = mas_allocated(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  	ma_free_rcu(mn);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35397,12 +35397,12 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	MT_BUG_ON(mt, mas_allocated(&mas) != allocated - 1);
>  	mas_push_node(&mas, mn);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != allocated);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	mas_destroy(&mas);
>  	allocated = mas_allocated(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35410,21 +35410,21 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	mas_store_prealloc(&mas, ptr);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
>  	MT_BUG_ON(mt, allocated != 1 + height * 3);
>  	mas_store_prealloc(&mas, ptr);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
>  	MT_BUG_ON(mt, allocated != 1 + height * 3);
>  	mas_store_prealloc(&mas, ptr);
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35432,14 +35432,14 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	mas_store_prealloc(&mas, ptr);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
>  	mt_set_non_kernel(1);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL & GFP_NOWAIT) == 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL & GFP_NOWAIT) == 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
>  	mas_destroy(&mas);
>  
>  
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL) != 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated == 0);
> @@ -35447,7 +35447,7 @@ static noinline void check_prealloc(struct maple_tree *mt)
>  	mas_store_prealloc(&mas, ptr);
>  	MT_BUG_ON(mt, mas_allocated(&mas) != 0);
>  	mt_set_non_kernel(1);
> -	MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL & GFP_NOWAIT) == 0);
> +	MT_BUG_ON(mt, mas_preallocate(&mas, GFP_KERNEL & GFP_NOWAIT) == 0);
>  	allocated = mas_allocated(&mas);
>  	height = mas_mt_height(&mas);
>  	MT_BUG_ON(mt, allocated != 0);
> -- 
> 2.34.1
> 



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