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-rw-r--r--mm/highmem.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/mm/highmem.c b/mm/highmem.c
index 1352a27951e3..0ee87a9e0cbf 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -369,6 +369,58 @@ void kunmap_high(struct page *page)
}
EXPORT_SYMBOL(kunmap_high);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
+ unsigned start2, unsigned end2)
+{
+ unsigned int i;
+
+ BUG_ON(end1 > page_size(page) || end2 > page_size(page));
+
+ for (i = 0; i < compound_nr(page); i++) {
+ void *kaddr = NULL;
+
+ if (start1 < PAGE_SIZE || start2 < PAGE_SIZE)
+ kaddr = kmap_atomic(page + i);
+
+ if (start1 >= PAGE_SIZE) {
+ start1 -= PAGE_SIZE;
+ end1 -= PAGE_SIZE;
+ } else {
+ unsigned this_end = min_t(unsigned, end1, PAGE_SIZE);
+
+ if (end1 > start1)
+ memset(kaddr + start1, 0, this_end - start1);
+ end1 -= this_end;
+ start1 = 0;
+ }
+
+ if (start2 >= PAGE_SIZE) {
+ start2 -= PAGE_SIZE;
+ end2 -= PAGE_SIZE;
+ } else {
+ unsigned this_end = min_t(unsigned, end2, PAGE_SIZE);
+
+ if (end2 > start2)
+ memset(kaddr + start2, 0, this_end - start2);
+ end2 -= this_end;
+ start2 = 0;
+ }
+
+ if (kaddr) {
+ kunmap_atomic(kaddr);
+ flush_dcache_page(page + i);
+ }
+
+ if (!end1 && !end2)
+ break;
+ }
+
+ BUG_ON((start1 | start2 | end1 | end2) != 0);
+}
+EXPORT_SYMBOL(zero_user_segments);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif /* CONFIG_HIGHMEM */
#if defined(HASHED_PAGE_VIRTUAL)