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SubjectRe: [RFC PATCH 2/5] mm, arch: unify vmemmap_populate altmap handling
On Wed, 26 Jul 2017 10:33:30 +0200
Michal Hocko <mhocko@kernel.org> wrote:

> From: Michal Hocko <mhocko@suse.com>
>
> vmem_altmap allows vmemmap_populate to allocate memmap (struct page
> array) from an alternative allocator rather than bootmem resp.
> kmalloc. Only x86 currently supports altmap handling, most likely
> because only nvdim code uses this mechanism currently and the code
> depends on ZONE_DEVICE which is present only for x86_64. This will
> change in follow up changes so we would like other architectures
> to support it as well.
>
> Provide vmemmap_populate generic implementation which simply resolves
> altmap and then call into arch specific __vmemmap_populate.
> Architectures then only need to use __vmemmap_alloc_block_buf to
> allocate the memmap. vmemmap_free then needs to call vmem_altmap_free
> if there is any altmap associated with the address.
>
> This patch shouldn't introduce any functional changes because
> to_vmem_altmap always returns NULL on !x86_x64.
>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Tony Luck <tony.luck@intel.com>
> Cc: Fenghua Yu <fenghua.yu@intel.com>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
> Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-ia64@vger.kernel.org
> Cc: x86@kernel.org
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> arch/arm64/mm/mmu.c | 9 ++++++---
> arch/ia64/mm/discontig.c | 4 +++-
> arch/powerpc/mm/init_64.c | 29 ++++++++++++++++++++---------
> arch/s390/mm/vmem.c | 7 ++++---
> arch/sparc/mm/init_64.c | 6 +++---
> arch/x86/mm/init_64.c | 4 ++--
> include/linux/memremap.h | 13 ++-----------
> include/linux/mm.h | 19 ++++++++++++++++++-
> mm/sparse-vmemmap.c | 2 +-
> 9 files changed, 59 insertions(+), 34 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 0c429ec6fde8..5de1161e7a1b 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -649,12 +649,15 @@ int kern_addr_valid(unsigned long addr)
> }
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
> #if !ARM64_SWAPPER_USES_SECTION_MAPS
> -int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> +int __meminit __vmemmap_populate(unsigned long start, unsigned long end, int node,
> + struct vmem_altmap *altmap)
> {
> + WARN(altmap, "altmap unsupported\n");
> return vmemmap_populate_basepages(start, end, node);
> }
> #else /* !ARM64_SWAPPER_USES_SECTION_MAPS */
> -int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> +int __meminit __vmemmap_populate(unsigned long start, unsigned long end, int node,
> + struct vmem_altmap *altmap)
> {
> unsigned long addr = start;
> unsigned long next;
> @@ -677,7 +680,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> if (pmd_none(*pmd)) {
> void *p = NULL;
>
> - p = vmemmap_alloc_block_buf(PMD_SIZE, node);
> + p = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> if (!p)
> return -ENOMEM;
>
> diff --git a/arch/ia64/mm/discontig.c b/arch/ia64/mm/discontig.c
> index 878626805369..2a939e877ced 100644
> --- a/arch/ia64/mm/discontig.c
> +++ b/arch/ia64/mm/discontig.c
> @@ -753,8 +753,10 @@ void arch_refresh_nodedata(int update_node, pg_data_t *update_pgdat)
> #endif
>
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
> -int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> +int __meminit __vmemmap_populate(unsigned long start, unsigned long end, int node,
> + struct vmem_altmap *altmap)
> {
> + WARN(altmap, "altmap unsupported\n");
> return vmemmap_populate_basepages(start, end, node);
> }
>
> diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
> index ec84b31c6c86..5ea5e870a589 100644
> --- a/arch/powerpc/mm/init_64.c
> +++ b/arch/powerpc/mm/init_64.c
> @@ -44,6 +44,7 @@
> #include <linux/slab.h>
> #include <linux/of_fdt.h>
> #include <linux/libfdt.h>
> +#include <linux/memremap.h>
>
> #include <asm/pgalloc.h>
> #include <asm/page.h>
> @@ -115,7 +116,8 @@ static struct vmemmap_backing *next;
> static int num_left;
> static int num_freed;
>
> -static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
> +static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node,
> + struct vmem_altmap *altmap)
> {
> struct vmemmap_backing *vmem_back;
> /* get from freed entries first */
> @@ -129,7 +131,7 @@ static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
>
> /* allocate a page when required and hand out chunks */
> if (!num_left) {
> - next = vmemmap_alloc_block(PAGE_SIZE, node);
> + next = __vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
> if (unlikely(!next)) {
> WARN_ON(1);
> return NULL;
> @@ -144,11 +146,12 @@ static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
>
> static __meminit void vmemmap_list_populate(unsigned long phys,
> unsigned long start,
> - int node)
> + int node,
> + struct vmem_altmap *altmap)
> {
> struct vmemmap_backing *vmem_back;
>
> - vmem_back = vmemmap_list_alloc(node);
> + vmem_back = vmemmap_list_alloc(node, altmap);
> if (unlikely(!vmem_back)) {
> WARN_ON(1);
> return;
> @@ -161,14 +164,15 @@ static __meminit void vmemmap_list_populate(unsigned long phys,
> vmemmap_list = vmem_back;
> }
>
> -int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> +int __meminit __vmemmap_populate(unsigned long start, unsigned long end, int node,
> + struct vmem_altmap *altmap)
> {
> unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
>
> /* Align to the page size of the linear mapping. */
> start = _ALIGN_DOWN(start, page_size);
>
> - pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
> + pr_debug("__vmemmap_populate %lx..%lx, node %d\n", start, end, node);
>
> for (; start < end; start += page_size) {
> void *p;
> @@ -177,11 +181,11 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> if (vmemmap_populated(start, page_size))
> continue;
>
> - p = vmemmap_alloc_block(page_size, node);
> + p = __vmemmap_alloc_block_buf(page_size, node, altmap);
> if (!p)
> return -ENOMEM;
>
> - vmemmap_list_populate(__pa(p), start, node);
> + vmemmap_list_populate(__pa(p), start, node, altmap);
>
> pr_debug(" * %016lx..%016lx allocated at %p\n",
> start, start + page_size, p);
> @@ -189,7 +193,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> rc = vmemmap_create_mapping(start, page_size, __pa(p));
> if (rc < 0) {
> pr_warning(
> - "vmemmap_populate: Unable to create vmemmap mapping: %d\n",
> + "__vmemmap_populate: Unable to create vmemmap mapping: %d\n",
> rc);
> return -EFAULT;
> }
> @@ -253,6 +257,12 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
> addr = vmemmap_list_free(start);
> if (addr) {
> struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
> + struct vmem_altmap *altmap = to_vmem_altmap((unsigned long) page);
> +
> + if (altmap) {
> + vmem_altmap_free(altmap, page_size >> PAGE_SHIFT);
> + goto unmap;
> + }
>
> if (PageReserved(page)) {
> /* allocated from bootmem */
> @@ -272,6 +282,7 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
> free_pages((unsigned long)(__va(addr)),
> get_order(page_size));
>
> +unmap:
> vmemmap_remove_mapping(start, page_size);
> }
> }
> diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
> index c33c94b4be60..07120bc137a1 100644
> --- a/arch/s390/mm/vmem.c
> +++ b/arch/s390/mm/vmem.c
> @@ -208,7 +208,8 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
> /*
> * Add a backed mem_map array to the virtual mem_map array.
> */
> -int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> +int __meminit __vmemmap_populate(unsigned long start, unsigned long end, int node,
> + struct vmem_altmap *altmap)
> {
> unsigned long pgt_prot, sgt_prot;
> unsigned long address = start;
> @@ -247,12 +248,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
> * use large frames even if they are only partially
> * used.
> * Otherwise we would have also page tables since
> - * vmemmap_populate gets called for each section
> + * __vmemmap_populate gets called for each section
> * separately. */
> if (MACHINE_HAS_EDAT1) {
> void *new_page;
>
> - new_page = vmemmap_alloc_block(PMD_SIZE, node);
> + new_page = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
> if (!new_page)
> goto out;
> pmd_val(*pm_dir) = __pa(new_page) | sgt_prot;

There is another call to vmemmap_alloc_block() in this function, a couple
of lines below, this should also be replaced by __vmemmap_alloc_block_buf().

We won't be able to use this directly on s390 yet, but your work should
get us a big step closer, thanks.

Regards,
Gerald

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