* [PATCH mm 2/2] mm: vm_insert_pages() checks if pte_index defined.
2020-02-28 0:46 [PATCH mm 1/2] mm: Define pte_index as macro for x86 Arjun Roy
@ 2020-02-28 0:46 ` Arjun Roy
2020-02-28 0:57 ` [PATCH mm 1/2] mm: Define pte_index as macro for x86 Stephen Rothwell
1 sibling, 0 replies; 4+ messages in thread
From: Arjun Roy @ 2020-02-28 0:46 UTC (permalink / raw)
To: davem, akpm, linux-mm; +Cc: arjunroy, soheil, edumazet, sfr, geert
From: Arjun Roy <arjunroy@google.com>
pte_index() is either defined as a macro (e.g. sparc64) or as an
inlined function (e.g. x86). vm_insert_pages() depends on pte_index
but it is not defined on all platforms (e.g. m68k).
To fix compilation of vm_insert_pages() on architectures not providing
pte_index(), we perform the following fix:
0. For platforms where it is meaningful, and defined as a macro, no
change is needed.
1. For platforms where it is meaningful and defined as an inlined
function, and we want to use it with vm_insert_pages(), we define
a degenerate macro of the form: #define pte_index pte_index
2. vm_insert_pages() checks for the existence of a pte_index macro
definition. If found, it implements a batched insert. If not found,
it devolves to calling vm_insert_page() in a loop.
This patch implements step 2.
Signed-off-by: Arjun Roy <arjunroy@google.com>
---
mm/memory.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index d6f834f7d145..33631a5b5c3f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1500,8 +1500,9 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
return retval;
}
+#ifdef pte_index
/* insert_pages() amortizes the cost of spinlock operations
- * when inserting pages in a loop.
+ * when inserting pages in a loop. Arch *must* define pte_index.
*/
static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
struct page **pages, unsigned long *num, pgprot_t prot)
@@ -1556,6 +1557,7 @@ static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
*num = remaining_pages_total;
return ret;
}
+#endif /* ifdef pte_index */
/**
* vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
@@ -1575,6 +1577,7 @@ static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
struct page **pages, unsigned long *num)
{
+#ifdef pte_index
const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
if (addr < vma->vm_start || end_addr >= vma->vm_end)
@@ -1586,6 +1589,18 @@ int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
}
/* Defer page refcount checking till we're about to map that page. */
return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
+#else
+ unsigned long idx = 0, pgcount = *num;
+ int err;
+
+ for (; idx < pgcount; ++idx) {
+ err = vm_insert_page(vma, addr + (PAGE_SIZE * idx), pages[idx]);
+ if (err)
+ break;
+ }
+ *num = pgcount - idx;
+ return err;
+#endif /* ifdef pte_index */
}
EXPORT_SYMBOL(vm_insert_pages);
--
2.25.1.481.gfbce0eb801-goog
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH mm 1/2] mm: Define pte_index as macro for x86
2020-02-28 0:46 [PATCH mm 1/2] mm: Define pte_index as macro for x86 Arjun Roy
2020-02-28 0:46 ` [PATCH mm 2/2] mm: vm_insert_pages() checks if pte_index defined Arjun Roy
@ 2020-02-28 0:57 ` Stephen Rothwell
2020-02-28 3:04 ` Arjun Roy
1 sibling, 1 reply; 4+ messages in thread
From: Stephen Rothwell @ 2020-02-28 0:57 UTC (permalink / raw)
To: Arjun Roy; +Cc: davem, akpm, linux-mm, arjunroy, soheil, edumazet, geert
[-- Attachment #1: Type: text/plain, Size: 800 bytes --]
Hi Arjun,
On Thu, 27 Feb 2020 16:46:56 -0800 Arjun Roy <arjunroy.kdev@gmail.com> wrote:
>
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 7e118660bbd9..6658c04bce83 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -823,6 +823,9 @@ static inline unsigned long pmd_index(unsigned long address)
> */
> #define mk_pte(page, pgprot) pfn_pte(page_to_pfn(page), (pgprot))
>
> +/* Degenerative definition so we can test if pte_index is defined for arch. */
> +#define pte_index pte_index
You should put this definition directly above the static inline function.
i.e.
#define pte_index pte_index
static inline unsigned long pte_index(unsigned long address)
...
--
Cheers,
Stephen Rothwell
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread