Mitigate a vmap lock contention

[PATCH 1/9] mm: vmalloc: Add va_alloc() helper

Posted by Uladzislau Rezki (Sony) 2 years, 8 months ago

Currently __alloc_vmap_area() function contains an open codded
logic that finds and adjusts a VA based on allocation request.

Introduce a va_alloc() helper that adjusts found VA only. It
will be used later at least in two places.

There is no a functional change as a result of this patch.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 mm/vmalloc.c | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 31ff782d368b..409285b68a67 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1482,6 +1482,32 @@ adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
 	return 0;
 }
 
+static unsigned long
+va_alloc(struct vmap_area *va,
+	struct rb_root *root, struct list_head *head,
+	unsigned long size, unsigned long align,
+	unsigned long vstart, unsigned long vend)
+{
+	unsigned long nva_start_addr;
+	int ret;
+
+	if (va->va_start > vstart)
+		nva_start_addr = ALIGN(va->va_start, align);
+	else
+		nva_start_addr = ALIGN(vstart, align);
+
+	/* Check the "vend" restriction. */
+	if (nva_start_addr + size > vend)
+		return vend;
+
+	/* Update the free vmap_area. */
+	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
+	if (WARN_ON_ONCE(ret))
+		return vend;
+
+	return nva_start_addr;
+}
+
 /*
  * Returns a start address of the newly allocated area, if success.
  * Otherwise a vend is returned that indicates failure.
@@ -1494,7 +1520,6 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
 	bool adjust_search_size = true;
 	unsigned long nva_start_addr;
 	struct vmap_area *va;
-	int ret;
 
 	/*
 	 * Do not adjust when:
@@ -1512,18 +1537,8 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
 	if (unlikely(!va))
 		return vend;
 
-	if (va->va_start > vstart)
-		nva_start_addr = ALIGN(va->va_start, align);
-	else
-		nva_start_addr = ALIGN(vstart, align);
-
-	/* Check the "vend" restriction. */
-	if (nva_start_addr + size > vend)
-		return vend;
-
-	/* Update the free vmap_area. */
-	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
-	if (WARN_ON_ONCE(ret))
+	nva_start_addr = va_alloc(va, root, head, size, align, vstart, vend);
+	if (nva_start_addr == vend)
 		return vend;
 
 #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
-- 
2.30.2

Re: [PATCH 1/9] mm: vmalloc: Add va_alloc() helper

Posted by Lorenzo Stoakes 2 years, 8 months ago

On Mon, May 22, 2023 at 01:08:41PM +0200, Uladzislau Rezki (Sony) wrote:
> Currently __alloc_vmap_area() function contains an open codded
> logic that finds and adjusts a VA based on allocation request.
>
> Introduce a va_alloc() helper that adjusts found VA only. It
> will be used later at least in two places.
>
> There is no a functional change as a result of this patch.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
>  mm/vmalloc.c | 41 ++++++++++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 13 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 31ff782d368b..409285b68a67 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1482,6 +1482,32 @@ adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
>  	return 0;
>  }
>
> +static unsigned long
> +va_alloc(struct vmap_area *va,
> +	struct rb_root *root, struct list_head *head,
> +	unsigned long size, unsigned long align,
> +	unsigned long vstart, unsigned long vend)
> +{
> +	unsigned long nva_start_addr;
> +	int ret;
> +
> +	if (va->va_start > vstart)
> +		nva_start_addr = ALIGN(va->va_start, align);
> +	else
> +		nva_start_addr = ALIGN(vstart, align);
> +
> +	/* Check the "vend" restriction. */
> +	if (nva_start_addr + size > vend)
> +		return vend;
> +
> +	/* Update the free vmap_area. */
> +	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
> +	if (WARN_ON_ONCE(ret))
> +		return vend;
> +
> +	return nva_start_addr;
> +}
> +
>  /*
>   * Returns a start address of the newly allocated area, if success.
>   * Otherwise a vend is returned that indicates failure.
> @@ -1494,7 +1520,6 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
>  	bool adjust_search_size = true;
>  	unsigned long nva_start_addr;
>  	struct vmap_area *va;
> -	int ret;
>
>  	/*
>  	 * Do not adjust when:
> @@ -1512,18 +1537,8 @@ __alloc_vmap_area(struct rb_root *root, struct list_head *head,
>  	if (unlikely(!va))
>  		return vend;
>
> -	if (va->va_start > vstart)
> -		nva_start_addr = ALIGN(va->va_start, align);
> -	else
> -		nva_start_addr = ALIGN(vstart, align);
> -
> -	/* Check the "vend" restriction. */
> -	if (nva_start_addr + size > vend)
> -		return vend;
> -
> -	/* Update the free vmap_area. */
> -	ret = adjust_va_to_fit_type(root, head, va, nva_start_addr, size);
> -	if (WARN_ON_ONCE(ret))
> +	nva_start_addr = va_alloc(va, root, head, size, align, vstart, vend);
> +	if (nva_start_addr == vend)
>  		return vend;
>
>  #if DEBUG_AUGMENT_LOWEST_MATCH_CHECK
> --
> 2.30.2
>

LGTM,

Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>

Re: [PATCH 1/9] mm: vmalloc: Add va_alloc() helper

Posted by Christoph Hellwig 2 years, 8 months ago

On Mon, May 22, 2023 at 01:08:41PM +0200, Uladzislau Rezki (Sony) wrote:
> Currently __alloc_vmap_area() function contains an open codded
> logic that finds and adjusts a VA based on allocation request.
> 
> Introduce a va_alloc() helper that adjusts found VA only. It
> will be used later at least in two places.
> 
> There is no a functional change as a result of this patch.
> 
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
>  mm/vmalloc.c | 41 ++++++++++++++++++++++++++++-------------
>  1 file changed, 28 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 31ff782d368b..409285b68a67 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1482,6 +1482,32 @@ adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
>  	return 0;
>  }
>  
> +static unsigned long
> +va_alloc(struct vmap_area *va,
> +	struct rb_root *root, struct list_head *head,
> +	unsigned long size, unsigned long align,
> +	unsigned long vstart, unsigned long vend)

Prototype continuations don't use a single tab indent.  Either two
tabs (my preference) or after the opening brace.  I.e.:

static unsigned long
va_alloc(struct vmap_area *va, struct rb_root *root, struct list_head *head,
		unsigned long size, unsigned long align, unsigned long vstart,
		unsigned long vend)


Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 1/9] mm: vmalloc: Add va_alloc() helper

Posted by Uladzislau Rezki 2 years, 8 months ago

On Mon, May 22, 2023 at 11:05:57PM -0700, Christoph Hellwig wrote:
> On Mon, May 22, 2023 at 01:08:41PM +0200, Uladzislau Rezki (Sony) wrote:
> > Currently __alloc_vmap_area() function contains an open codded
> > logic that finds and adjusts a VA based on allocation request.
> > 
> > Introduce a va_alloc() helper that adjusts found VA only. It
> > will be used later at least in two places.
> > 
> > There is no a functional change as a result of this patch.
> > 
> > Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > ---
> >  mm/vmalloc.c | 41 ++++++++++++++++++++++++++++-------------
> >  1 file changed, 28 insertions(+), 13 deletions(-)
> > 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 31ff782d368b..409285b68a67 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -1482,6 +1482,32 @@ adjust_va_to_fit_type(struct rb_root *root, struct list_head *head,
> >  	return 0;
> >  }
> >  
> > +static unsigned long
> > +va_alloc(struct vmap_area *va,
> > +	struct rb_root *root, struct list_head *head,
> > +	unsigned long size, unsigned long align,
> > +	unsigned long vstart, unsigned long vend)
> 
> Prototype continuations don't use a single tab indent.  Either two
> tabs (my preference) or after the opening brace.  I.e.:
> 
Will go with two tabs.

> static unsigned long
> va_alloc(struct vmap_area *va, struct rb_root *root, struct list_head *head,
> 		unsigned long size, unsigned long align, unsigned long vstart,
> 		unsigned long vend)
> 
> 
> Otherwise looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
>
Added.

Appreciate you look at it!

--
Uladizislau Rezki