From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id CBAC56B0292 for ; Thu, 25 May 2017 02:46:50 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id h76so175792403pfh.15 for ; Wed, 24 May 2017 23:46:50 -0700 (PDT) Received: from mga02.intel.com (mga02.intel.com. [134.134.136.20]) by mx.google.com with ESMTPS id u69si26530689pgb.168.2017.05.24.23.46.49 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 May 2017 23:46:50 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm 01/13] mm, THP, swap: Support to clear swap cache flag for THP swapped out Date: Thu, 25 May 2017 14:46:23 +0800 Message-Id: <20170525064635.2832-2-ying.huang@intel.com> In-Reply-To: <20170525064635.2832-1-ying.huang@intel.com> References: <20170525064635.2832-1-ying.huang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: 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 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 8a6cdf9e55f9..4cd02dec6894 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1167,22 +1167,40 @@ 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) -- 2.11.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org