sugar/linux
1
0
Fork 0
Code Activity

mm/gup: drop nth_page() usage in unpin_user_page_range_dirty_lock()

Browse Source 
There is the concern that unpin_user_page_range_dirty_lock() might do some
weird merging of PFN ranges -- either now or in the future -- such that
PFN range is contiguous but the page range might not be.

Let's sanity-check for that and drop the nth_page() usage.

Link: https://lkml.kernel.org/r/20250901150359.867252-35-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand
2025-09-01 17:03:55 +02:00
committed by Andrew Morton
parent ce00897b94
commit b5ba761a7f
1 changed files with 7 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
mm/gup.c
View File

@@ -237,7 +237,7 @@ void folio_add_pin(struct folio *folio)
static inline struct folio *gup_folio_range_next(struct page *start,
unsigned long npages, unsigned long i, unsigned int *ntails)
{
struct page *next = nth_page(start, i);
struct page *next = start + i;
struct folio *folio = page_folio(next);
unsigned int nr = 1;
@@ -342,6 +342,10 @@ EXPORT_SYMBOL(unpin_user_pages_dirty_lock);
* "gup-pinned page range" refers to a range of pages that has had one of the
* pin_user_pages() variants called on that page.
*
* The page range must be truly physically contiguous: the page range
* corresponds to a contiguous PFN range and all pages can be iterated
* naturally.
*
* For the page ranges defined by [page .. page+npages], make that range (or
* its head pages, if a compound page) dirty, if @make_dirty is true, and if the
* page range was previously listed as clean.
@@ -359,6 +363,8 @@ void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,
struct folio *folio;
unsigned int nr;
VM_WARN_ON_ONCE(!page_range_contiguous(page, npages));
for (i = 0; i < npages; i += nr) {
folio = gup_folio_range_next(page, npages, i, &nr);
if (make_dirty && !folio_test_dirty(folio)) {