"Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx> writes:
> This is in preparation to update radix to implement vmemmap optimization
> for devdax. Below are the rules w.r.t radix vmemmap mapping
>
> 1. First try to map things using PMD (2M)
> 2. With altmap if altmap cross-boundary check returns true, fall back to
> PAGE_SIZE
> 3. If we can't allocate PMD_SIZE backing memory for vmemmap, fallback to
> PAGE_SIZE
>
> On removing vmemmap mapping, check if every subsection that is using the
> vmemmap area is invalid. If found to be invalid, that implies we can safely
> free the vmemmap area. We don't use the PAGE_UNUSED pattern used by x86
> because with 64K page size, we need to do the above check even at the
> PAGE_SIZE granularity.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/book3s/64/radix.h | 2 +
> arch/powerpc/include/asm/pgtable.h | 4 +
> arch/powerpc/mm/book3s64/radix_pgtable.c | 326 +++++++++++++++++++--
> arch/powerpc/mm/init_64.c | 26 +-
> 4 files changed, 327 insertions(+), 31 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
> index 2ef92f36340f..f1461289643a 100644
> --- a/arch/powerpc/include/asm/book3s/64/radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/radix.h
> @@ -331,6 +331,8 @@ extern int __meminit radix__vmemmap_create_mapping(unsigned long start,
> unsigned long phys);
> int __meminit radix__vmemmap_populate(unsigned long start, unsigned long end,
> int node, struct vmem_altmap *altmap);
> +void __ref radix__vmemmap_free(unsigned long start, unsigned long end,
> + struct vmem_altmap *altmap);
> extern void radix__vmemmap_remove_mapping(unsigned long start,
> unsigned long page_size);
>
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 6a88bfdaa69b..68817ea7f994 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -165,6 +165,10 @@ static inline bool is_ioremap_addr(const void *x)
>
> return addr >= IOREMAP_BASE && addr < IOREMAP_END;
> }
> +
> +int __meminit vmemmap_populated(unsigned long vmemmap_addr, int vmemmap_map_size);
> +bool altmap_cross_boundary(struct vmem_altmap *altmap, unsigned long start,
> + unsigned long page_size);
> #endif /* CONFIG_PPC64 */
>
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
> index 227fea53c217..9a7f3707b6fb 100644
> --- a/arch/powerpc/mm/book3s64/radix_pgtable.c
> +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
> @@ -744,8 +744,59 @@ static void free_pud_table(pud_t *pud_start, p4d_t *p4d)
> p4d_clear(p4d);
> }
>
> +#ifdef CONFIG_SPARSEMEM_VMEMMAP
> +static bool __meminit vmemmap_pmd_is_unused(unsigned long addr, unsigned long end)
> +{
> + unsigned long start = ALIGN_DOWN(addr, PMD_SIZE);
> +
> + return !vmemmap_populated(start, PMD_SIZE);
> +}
> +
> +static bool __meminit vmemmap_page_is_unused(unsigned long addr, unsigned long end)
> +{
> + unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
> +
> + return !vmemmap_populated(start, PAGE_SIZE);
> +
> +}
> +#endif
> +
> +static void __meminit free_vmemmap_pages(struct page *page,
> + struct vmem_altmap *altmap,
> + int order)
> +{
> + unsigned int nr_pages = 1 << order;
> +
> + if (altmap) {
> + unsigned long alt_start, alt_end;
> + unsigned long base_pfn = page_to_pfn(page);
> +
> + /*
> + * with 2M vmemmap mmaping we can have things setup
> + * such that even though atlmap is specified we never
> + * used altmap.
> + */
> + alt_start = altmap->base_pfn;
> + alt_end = altmap->base_pfn + altmap->reserve +
> + altmap->free + altmap->alloc + altmap->align;
> +
> + if (base_pfn >= alt_start && base_pfn < alt_end) {
> + vmem_altmap_free(altmap, nr_pages);
> + return;
> + }
> + }
> +
Please take this diff on top of this patch when adding this series to
-mm .
commit 613569d9517be60611a86bf4b9821b150c4c4954
Author: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Date: Mon Jul 24 22:49:29 2023 +0530
powerpc/mm/altmap: Fix altmap boundary check
altmap->free includes the entire free space from which altmap blocks
can be allocated. So when checking whether the kernel is doing altmap
block free, compute the boundary correctly.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 7761c2e93bff..ed63c2953b54 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c
@@ -766,8 +766,7 @@ static void __meminit free_vmemmap_pages(struct page *page,
* used altmap.
*/
alt_start = altmap->base_pfn;
- alt_end = altmap->base_pfn + altmap->reserve +
- altmap->free + altmap->alloc + altmap->align;
+ alt_end = altmap->base_pfn + altmap->reserve + altmap->free;
if (base_pfn >= alt_start && base_pfn < alt_end) {
vmem_altmap_free(altmap, nr_pages);
