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-rw-r--r--mm/rmap.c25
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 1ea4e6fcee7..059774712c0 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -659,23 +659,30 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
}
/*
- * It would be tidy to reset the PageAnon mapping here,
- * but that might overwrite a racing page_add_anon_rmap
- * which increments mapcount after us but sets mapping
- * before us: so leave the reset to free_hot_cold_page,
- * and remember that it's only reliable while mapped.
- * Leaving it set also helps swapoff to reinstate ptes
- * faster for those pages still in swapcache.
+ * 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);
+ mem_cgroup_uncharge_page(page);
__dec_zone_page_state(page,
- PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
+ 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
+ * which increments mapcount after us but sets mapping
+ * before us: so leave the reset to free_hot_cold_page,
+ * and remember that it's only reliable while mapped.
+ * Leaving it set also helps swapoff to reinstate ptes
+ * faster for those pages still in swapcache.
+ */
}
}