Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752869AbdGXFTF (ORCPT ); Mon, 24 Jul 2017 01:19:05 -0400 Received: from mga04.intel.com ([192.55.52.120]:64840 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752689AbdGXFSt (ORCPT ); Mon, 24 Jul 2017 01:18:49 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,405,1496127600"; d="scan'208";a="290458673" From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Huang Ying , Johannes Weiner , Minchan Kim , Hugh Dickins , Shaohua Li , Rik van Riel Subject: [PATCH -mm -v3 01/12] mm, THP, swap: Support to clear swap cache flag for THP swapped out Date: Mon, 24 Jul 2017 13:18:29 +0800 Message-Id: <20170724051840.2309-2-ying.huang@intel.com> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170724051840.2309-1-ying.huang@intel.com> References: <20170724051840.2309-1-ying.huang@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2512 Lines: 78 From: Huang Ying Previously, swapcache_free_cluster() is used only in the error path of shrink_page_list() to free the swap cluster just allocated if the THP (Transparent Huge Page) is failed to be split. In this patch, it is enhanced to clear the swap cache flag (SWAP_HAS_CACHE) for the swap cluster that holds the contents of THP swapped out. This will be used in delaying splitting THP after swapping out support. Because there is no THP swapping in as a whole support yet, after clearing the swap cache flag, the swap cluster backing the THP swapped out will be split. So that the swap slots in the swap cluster can be swapped in as normal pages later. Signed-off-by: "Huang, Ying" Cc: Johannes Weiner Cc: Minchan Kim Cc: Hugh Dickins Cc: Shaohua Li Cc: Rik van Riel --- mm/swapfile.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 6ba4aab2db0b..c32e9b23d642 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1168,22 +1168,40 @@ static void swapcache_free_cluster(swp_entry_t entry) struct swap_cluster_info *ci; struct swap_info_struct *si; unsigned char *map; - unsigned int i; + unsigned int i, free_entries = 0; + unsigned char val; - si = swap_info_get(entry); + si = _swap_info_get(entry); if (!si) return; ci = lock_cluster(si, offset); map = si->swap_map + offset; for (i = 0; i < SWAPFILE_CLUSTER; i++) { - VM_BUG_ON(map[i] != SWAP_HAS_CACHE); - map[i] = 0; + val = map[i]; + VM_BUG_ON(!(val & SWAP_HAS_CACHE)); + if (val == SWAP_HAS_CACHE) + free_entries++; + } + if (!free_entries) { + for (i = 0; i < SWAPFILE_CLUSTER; i++) + map[i] &= ~SWAP_HAS_CACHE; } unlock_cluster(ci); - mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); - swap_free_cluster(si, idx); - spin_unlock(&si->lock); + if (free_entries == SWAPFILE_CLUSTER) { + spin_lock(&si->lock); + ci = lock_cluster(si, offset); + memset(map, 0, SWAPFILE_CLUSTER); + unlock_cluster(ci); + mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); + swap_free_cluster(si, idx); + spin_unlock(&si->lock); + } else if (free_entries) { + for (i = 0; i < SWAPFILE_CLUSTER; i++, entry.val++) { + if (!__swap_entry_free(si, entry, SWAP_HAS_CACHE)) + free_swap_slot(entry); + } + } } #else static inline void swapcache_free_cluster(swp_entry_t entry) -- 2.13.2