Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added
support for hugepage vmalloc mappings, it also added the flag
VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to
be performed with 0-order non-huge pages. This flag is not accessible
when calling vmalloc, the only option is to call directly
__vmalloc_node_range, which is not exported.
This means that a module can't vmalloc memory with small pages.
Case in point: KVM on s390x needs to vmalloc a large area, and it needs
to be mapped with non-huge pages, because of a hardware limitation.
This patch adds the function vmalloc_no_huge, which works like vmalloc,
but it is guaranteed to always back the mapping using small pages. This
new function is exported, therefore it is usable by modules.
Signed-off-by: Claudio Imbrenda <[email protected]>
Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
Acked-by: Nicholas Piggin <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Christoph Hellwig <[email protected]>
---
include/linux/vmalloc.h | 1 +
mm/vmalloc.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 4d668abb6391..bfaaf0b6fa76 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -135,6 +135,7 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller);
void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
int node, const void *caller);
+void *vmalloc_no_huge(unsigned long size);
extern void vfree(const void *addr);
extern void vfree_atomic(const void *addr);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a13ac524f6ff..296a2fcc3fbe 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2998,6 +2998,22 @@ void *vmalloc(unsigned long size)
}
EXPORT_SYMBOL(vmalloc);
+/**
+ * vmalloc_no_huge - allocate virtually contiguous memory using small pages
+ * @size: allocation size
+ *
+ * Allocate enough non-huge pages to cover @size from the page level
+ * allocator and map them into contiguous kernel virtual space.
+ *
+ * Return: pointer to the allocated memory or %NULL on error
+ */
+void *vmalloc_no_huge(unsigned long size)
+{
+ return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, GFP_KERNEL, PAGE_KERNEL,
+ VM_NO_HUGE_VMAP, NUMA_NO_NODE, __builtin_return_address(0));
+}
+EXPORT_SYMBOL(vmalloc_no_huge);
+
/**
* vzalloc - allocate virtually contiguous memory with zero fill
* @size: allocation size
--
2.31.1
On 14.06.21 15:23, Claudio Imbrenda wrote:
> Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added
> support for hugepage vmalloc mappings, it also added the flag
> VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to
> be performed with 0-order non-huge pages. This flag is not accessible
> when calling vmalloc, the only option is to call directly
> __vmalloc_node_range, which is not exported.
>
> This means that a module can't vmalloc memory with small pages.
>
> Case in point: KVM on s390x needs to vmalloc a large area, and it needs
> to be mapped with non-huge pages, because of a hardware limitation.
>
> This patch adds the function vmalloc_no_huge, which works like vmalloc,
> but it is guaranteed to always back the mapping using small pages. This
> new function is exported, therefore it is usable by modules.
>
> Signed-off-by: Claudio Imbrenda <[email protected]>
> Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
> Acked-by: Nicholas Piggin <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Nicholas Piggin <[email protected]>
> Cc: Uladzislau Rezki (Sony) <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: David Rientjes <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
> ---
> include/linux/vmalloc.h | 1 +
> mm/vmalloc.c | 16 ++++++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 4d668abb6391..bfaaf0b6fa76 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -135,6 +135,7 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
> const void *caller);
> void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
> int node, const void *caller);
> +void *vmalloc_no_huge(unsigned long size);
>
> extern void vfree(const void *addr);
> extern void vfree_atomic(const void *addr);
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index a13ac524f6ff..296a2fcc3fbe 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2998,6 +2998,22 @@ void *vmalloc(unsigned long size)
> }
> EXPORT_SYMBOL(vmalloc);
>
> +/**
> + * vmalloc_no_huge - allocate virtually contiguous memory using small pages
> + * @size: allocation size
> + *
> + * Allocate enough non-huge pages to cover @size from the page level
> + * allocator and map them into contiguous kernel virtual space.
> + *
> + * Return: pointer to the allocated memory or %NULL on error
> + */
> +void *vmalloc_no_huge(unsigned long size)
> +{
> + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, GFP_KERNEL, PAGE_KERNEL,
> + VM_NO_HUGE_VMAP, NUMA_NO_NODE, __builtin_return_address(0));
> +}
> +EXPORT_SYMBOL(vmalloc_no_huge);
> +
> /**
> * vzalloc - allocate virtually contiguous memory with zero fill
> * @size: allocation size
>
Reviewed-by: David Hildenbrand <[email protected]>
--
Thanks,
David / dhildenb
> On 14.06.21 15:23, Claudio Imbrenda wrote:
> > Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added
> > support for hugepage vmalloc mappings, it also added the flag
> > VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to
> > be performed with 0-order non-huge pages. This flag is not accessible
> > when calling vmalloc, the only option is to call directly
> > __vmalloc_node_range, which is not exported.
> >
> > This means that a module can't vmalloc memory with small pages.
> >
> > Case in point: KVM on s390x needs to vmalloc a large area, and it needs
> > to be mapped with non-huge pages, because of a hardware limitation.
> >
> > This patch adds the function vmalloc_no_huge, which works like vmalloc,
> > but it is guaranteed to always back the mapping using small pages. This
> > new function is exported, therefore it is usable by modules.
> >
> > Signed-off-by: Claudio Imbrenda <[email protected]>
> > Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
> > Acked-by: Nicholas Piggin <[email protected]>
> > Cc: Andrew Morton <[email protected]>
> > Cc: Nicholas Piggin <[email protected]>
> > Cc: Uladzislau Rezki (Sony) <[email protected]>
> > Cc: Catalin Marinas <[email protected]>
> > Cc: Thomas Gleixner <[email protected]>
> > Cc: Ingo Molnar <[email protected]>
> > Cc: David Rientjes <[email protected]>
> > Cc: Christoph Hellwig <[email protected]>
> > ---
> > include/linux/vmalloc.h | 1 +
> > mm/vmalloc.c | 16 ++++++++++++++++
> > 2 files changed, 17 insertions(+)
> >
> > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> > index 4d668abb6391..bfaaf0b6fa76 100644
> > --- a/include/linux/vmalloc.h
> > +++ b/include/linux/vmalloc.h
> > @@ -135,6 +135,7 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
> > const void *caller);
> > void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
> > int node, const void *caller);
> > +void *vmalloc_no_huge(unsigned long size);
> > extern void vfree(const void *addr);
> > extern void vfree_atomic(const void *addr);
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index a13ac524f6ff..296a2fcc3fbe 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -2998,6 +2998,22 @@ void *vmalloc(unsigned long size)
> > }
> > EXPORT_SYMBOL(vmalloc);
> > +/**
> > + * vmalloc_no_huge - allocate virtually contiguous memory using small pages
> > + * @size: allocation size
> > + *
> > + * Allocate enough non-huge pages to cover @size from the page level
> > + * allocator and map them into contiguous kernel virtual space.
> > + *
> > + * Return: pointer to the allocated memory or %NULL on error
> > + */
> > +void *vmalloc_no_huge(unsigned long size)
> > +{
> > + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, GFP_KERNEL, PAGE_KERNEL,
> > + VM_NO_HUGE_VMAP, NUMA_NO_NODE, __builtin_return_address(0));
> > +}
> > +EXPORT_SYMBOL(vmalloc_no_huge);
> > +
> > /**
> > * vzalloc - allocate virtually contiguous memory with zero fill
> > * @size: allocation size
> >
>
> Reviewed-by: David Hildenbrand <[email protected]>
>
>
Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
--
Vlad Rezki
On Mon, Jun 14, 2021 at 03:23:56PM +0200, Claudio Imbrenda wrote:
> +void *vmalloc_no_huge(unsigned long size)
> +{
> + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, GFP_KERNEL, PAGE_KERNEL,
> + VM_NO_HUGE_VMAP, NUMA_NO_NODE, __builtin_return_address(0));
Please avoid the overly long lines in favor of something actually
human-readable like:
return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
GFP_KERNEL, PAGE_KERNEL, VM_NO_HUGE_VMAP,
NUMA_NO_NODE, __builtin_return_address(0));
On Mon, 14 Jun 2021, Claudio Imbrenda wrote:
> Commit 121e6f3258fe3 ("mm/vmalloc: hugepage vmalloc mappings") added
> support for hugepage vmalloc mappings, it also added the flag
> VM_NO_HUGE_VMAP for __vmalloc_node_range to request the allocation to
> be performed with 0-order non-huge pages. This flag is not accessible
> when calling vmalloc, the only option is to call directly
> __vmalloc_node_range, which is not exported.
>
> This means that a module can't vmalloc memory with small pages.
>
> Case in point: KVM on s390x needs to vmalloc a large area, and it needs
> to be mapped with non-huge pages, because of a hardware limitation.
>
> This patch adds the function vmalloc_no_huge, which works like vmalloc,
> but it is guaranteed to always back the mapping using small pages. This
> new function is exported, therefore it is usable by modules.
>
> Signed-off-by: Claudio Imbrenda <[email protected]>
> Reviewed-by: Uladzislau Rezki (Sony) <[email protected]>
> Acked-by: Nicholas Piggin <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Nicholas Piggin <[email protected]>
> Cc: Uladzislau Rezki (Sony) <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: David Rientjes <[email protected]>
> Cc: Christoph Hellwig <[email protected]>
Acked-by: David Rientjes <[email protected]>