/*
* Check that @page is mapped at @address into @mm.
*
+ * If @sync is false, page_check_address may perform a racy check to avoid
+ * the page table lock when the pte is not present (helpful when reclaiming
+ * highly shared pages).
+ *
* On success returns with pte mapped and locked.
*/
pte_t *page_check_address(struct page *page, struct mm_struct *mm,
- unsigned long address, spinlock_t **ptlp)
+ unsigned long address, spinlock_t **ptlp, int sync)
{
pgd_t *pgd;
pud_t *pud;
pte = pte_offset_map(pmd, address);
/* Make a quick check before getting the lock */
- if (!pte_present(*pte)) {
+ if (!sync && !pte_present(*pte)) {
pte_unmap(pte);
return NULL;
}
if (address == -EFAULT)
goto out;
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
goto out;
referenced += page_referenced_anon(page, mem_cont);
else if (is_locked)
referenced += page_referenced_file(page, mem_cont);
- else if (TestSetPageLocked(page))
+ else if (!trylock_page(page))
referenced++;
else {
if (page->mapping)
if (address == -EFAULT)
goto out;
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, 1);
if (!pte)
goto out;
BUG();
}
+ /*
+ * Now that the last pte has gone, s390 must transfer dirty
+ * flag from storage key to struct page. We can usually skip
+ * this if the page is anon, so about to be freed; but perhaps
+ * not if it's in swapcache - there might be another pte slot
+ * containing the swap entry, but page not yet written to swap.
+ */
+ if ((!PageAnon(page) || PageSwapCache(page)) &&
+ page_test_dirty(page)) {
+ page_clear_dirty(page);
+ set_page_dirty(page);
+ }
+
+ mem_cgroup_uncharge_page(page);
+ __dec_zone_page_state(page,
+ PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
/*
* It would be tidy to reset the PageAnon mapping here,
* but that might overwrite a racing page_add_anon_rmap
* Leaving it set also helps swapoff to reinstate ptes
* faster for those pages still in swapcache.
*/
- if (page_test_dirty(page)) {
- page_clear_dirty(page);
- set_page_dirty(page);
- }
- mem_cgroup_uncharge_page(page);
-
- __dec_zone_page_state(page,
- PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
}
}
if (address == -EFAULT)
goto out;
- pte = page_check_address(page, mm, address, &ptl);
+ pte = page_check_address(page, mm, address, &ptl, 0);
if (!pte)
goto out;