struct page *page = *pages;
struct folio *folio = page_folio(page);
- if (!folio_test_anon(folio))
+ if (is_zero_page(page) ||
+ !folio_test_anon(folio))
continue;
if (!folio_test_large(folio) || folio_test_hugetlb(folio))
VM_BUG_ON_PAGE(!PageAnonExclusive(&folio->page), page);
else if (flags & FOLL_PIN) {
struct folio *folio;
+ /*
+ * Don't take a pin on the zero page - it's not going anywhere
+ * and it is used in a *lot* of places.
+ */
+ if (is_zero_page(page))
+ return page_folio(page);
+
/*
* Can't do FOLL_LONGTERM + FOLL_PIN gup fast path if not in a
* right zone, so fail and let the caller fall back to the slow
static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
{
if (flags & FOLL_PIN) {
+ if (is_zero_folio(folio))
+ return;
node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs);
if (folio_test_large(folio))
atomic_sub(refs, &folio->_pincount);
if (flags & FOLL_GET)
folio_ref_inc(folio);
else if (flags & FOLL_PIN) {
+ /*
+ * Don't take a pin on the zero page - it's not going anywhere
+ * and it is used in a *lot* of places.
+ */
+ if (is_zero_page(page))
+ return 0;
+
/*
* Similar to try_grab_folio(): be sure to *also*
* increment the normal page refcount field at least once,
len = nr_pages << PAGE_SHIFT;
if (check_add_overflow(start, len, &end))
return 0;
+ if (end > TASK_SIZE_MAX)
+ return -EFAULT;
if (unlikely(!access_ok((void __user *)start, len)))
return -EFAULT;
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for further details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page() will not remove pins from it.
*/
int pin_user_pages_fast(unsigned long start, int nr_pages,
unsigned int gup_flags, struct page **pages)
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages_remote(struct mm_struct *mm,
unsigned long start, unsigned long nr_pages,
*
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
* see Documentation/core-api/pin_user_pages.rst for details.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages(unsigned long start, unsigned long nr_pages,
unsigned int gup_flags, struct page **pages,
* pin_user_pages_unlocked() is the FOLL_PIN variant of
* get_user_pages_unlocked(). Behavior is the same, except that this one sets
* FOLL_PIN and rejects FOLL_GET.
+ *
+ * Note that if a zero_page is amongst the returned pages, it will not have
+ * pins in it and unpin_user_page*() will not remove pins from it.
*/
long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags)