diff options
| -rw-r--r-- | mm/ksm.c | 35 |
1 files changed, 23 insertions, 12 deletions
@@ -1367,13 +1367,14 @@ struct page *stable_node_dup(struct stable_node **_stable_node_dup, put_page(_tree_page); } - /* - * nr is relevant only if prune_stale_stable_nodes is true, - * otherwise we may break the loop at nr == 1 even if there - * are multiple entries. - */ - if (prune_stale_stable_nodes && found) { - if (nr == 1) { + if (found) { + /* + * nr is counting all dups in the chain only if + * prune_stale_stable_nodes is true, otherwise we may + * break the loop at nr == 1 even if there are + * multiple entries. + */ + if (prune_stale_stable_nodes && nr == 1) { /* * If there's not just one entry it would * corrupt memory, better BUG_ON. In KSM @@ -1404,12 +1405,22 @@ struct page *stable_node_dup(struct stable_node **_stable_node_dup, * time. */ stable_node = NULL; - } else if (__is_page_sharing_candidate(found, 1)) { + } else if (stable_node->hlist.first != &found->hlist_dup && + __is_page_sharing_candidate(found, 1)) { /* - * Refile our candidate at the head - * after the prune if our candidate - * can accept one more future sharing - * in addition to the one underway. + * If the found stable_node dup can accept one + * more future merge (in addition to the one + * that is underway) and is not at the head of + * the chain, put it there so next search will + * be quicker in the !prune_stale_stable_nodes + * case. + * + * NOTE: it would be inaccurate to use nr > 1 + * instead of checking the hlist.first pointer + * directly, because in the + * prune_stale_stable_nodes case "nr" isn't + * the position of the found dup in the chain, + * but the total number of dups in the chain. */ hlist_del(&found->hlist_dup); hlist_add_head(&found->hlist_dup, |