tuntap: set SOCK_ZEROCOPY flag during open

[~andy/linux] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index cb1c9dedf9b65c08a4a6d9d6f81ee01f2cb44c36..010d6c14129ae320ab9655a573d49af33e034659 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4108,8 +4108,6 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
        if (mem_cgroup_disabled())
                return NULL;
 
-       VM_BUG_ON(PageSwapCache(page));
-
        if (PageTransHuge(page)) {
                nr_pages <<= compound_order(page);
                VM_BUG_ON(!PageTransHuge(page));
@@ -4205,6 +4203,18 @@ void mem_cgroup_uncharge_page(struct page *page)
        if (page_mapped(page))
                return;
        VM_BUG_ON(page->mapping && !PageAnon(page));
+       /*
+        * If the page is in swap cache, uncharge should be deferred
+        * to the swap path, which also properly accounts swap usage
+        * and handles memcg lifetime.
+        *
+        * Note that this check is not stable and reclaim may add the
+        * page to swap cache at any time after this.  However, if the
+        * page is not in swap cache by the time page->mapcount hits
+        * 0, there won't be any page table references to the swap
+        * slot, and reclaim will free it and not actually write the
+        * page to disk.
+        */
        if (PageSwapCache(page))
                return;
        __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);