On 2023/3/14 16:31, Matthew Wilcox wrote:
On Tue, Mar 14, 2023 at 03:37:33AM +0000, Peng Zhang wrote:
+++ b/include/linux/mm.h
@@ -3546,9 +3546,8 @@ extern void copy_user_huge_page(struct page *dst, struct page *src,
unsigned long addr_hint,
struct vm_area_struct *vma,
unsigned int pages_per_huge_page);
-extern long copy_huge_page_from_user(struct page *dst_page,
+extern long copy_large_folio_from_user(struct folio *dst_folio,
You can drop the 'extern'.
Got it.
+++ b/mm/memory.c
@@ -5769,26 +5769,28 @@ void copy_user_huge_page(struct page *dst, struct page *src,
process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
}
-long copy_huge_page_from_user(struct page *dst_page,
+long copy_large_folio_from_user(struct folio *dst_folio,
const void __user *usr_src,
- unsigned int pages_per_huge_page,
bool allow_pagefault)
{
void *page_kaddr;
unsigned long i, rc = 0;
- unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
+ unsigned int nr_pages = folio_nr_pages(dst_folio);
+ unsigned long ret_val = nr_pages * PAGE_SIZE;
struct page *subpage;
+ struct folio *inner_folio;
What is an 'inner folio'?
- for (i = 0; i < pages_per_huge_page; i++) {
- subpage = nth_page(dst_page, i);
+ for (i = 0; i < nr_pages; i++) {
+ subpage = folio_page(dst_folio, i);
+ inner_folio = page_folio(subpage);
if (allow_pagefault)
- page_kaddr = kmap(subpage);
+ page_kaddr = kmap_local_folio(inner_folio, 0);
This doesn't do what you think it does. Did you test this?
else
page_kaddr = kmap_atomic(subpage);
Pretty sure all this should be converted to kmap_local and the atomic
bits should go away.
rc = copy_from_user(page_kaddr,
usr_src + i * PAGE_SIZE, PAGE_SIZE);
if (allow_pagefault)
- kunmap(subpage);
+ kunmap_local(page_kaddr);
else
kunmap_atomic(page_kaddr);
@@ -5796,7 +5798,7 @@ long copy_huge_page_from_user(struct page *dst_page,
if (rc)
break;
- flush_dcache_page(subpage);
+ flush_dcache_folio(inner_folio);
The flush should probably be pulled outside the loop.
+ err = copy_large_folio_from_user(folio,
+ (const void __user *) src_addr, true);
I wonder if this shouldn't be 'copy_folio_from_user()'. after all,
it'll work for any size folio, right?
Thanks for your review.
I'll rename copy_large_folio_from_user() to copy_folio_from_user().
I'll delete the inner_folio. kmap() and kmap_atomic() will be
converted to the following code.
page_kaddr = kmap_local_page(subpage);
if (!allow_pagefault)
pagefault_disable();
rc = copy_from_user(page_kaddr,
usr_src + i * PAGE_SIZE, PAGE_SIZE);
if (!allow_pagefault)
pagefault_enable();
kunmap_local(page_kaddr);
flush_dcache_folio() will be placed outside the loop.
I'll fix all this in a v2 of this patch series.
Thanks,
Peng.
