From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id 5A7946B0493 for ; Wed, 9 May 2018 04:39:13 -0400 (EDT) Received: by mail-pl0-f72.google.com with SMTP id b36-v6so3374818pli.2 for ; Wed, 09 May 2018 01:39:13 -0700 (PDT) Received: from mga18.intel.com (mga18.intel.com. [134.134.136.126]) by mx.google.com with ESMTPS id t144-v6si21177836pgb.94.2018.05.09.01.39.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 May 2018 01:39:12 -0700 (PDT) From: "Huang, Ying" Subject: [PATCH -mm -V2 04/21] mm, THP, swap: Support PMD swap mapping in swapcache_free_cluster() Date: Wed, 9 May 2018 16:38:29 +0800 Message-Id: <20180509083846.14823-5-ying.huang@intel.com> In-Reply-To: <20180509083846.14823-1-ying.huang@intel.com> References: <20180509083846.14823-1-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 , "Kirill A. Shutemov" , Andrea Arcangeli , Michal Hocko , Johannes Weiner , Shaohua Li , Hugh Dickins , Minchan Kim , Rik van Riel , Dave Hansen , Naoya Horiguchi , Zi Yan From: Huang Ying Previously, during swapout, all PMD page mapping will be split and replaced with PTE swap mapping. And when clearing the SWAP_HAS_CACHE flag for the huge swap cluster in swapcache_free_cluster(), the huge swap cluster will be split. Now, during swapout, the PMD page mapping will be changed to PMD swap mapping. So when clearing the SWAP_HAS_CACHE flag, the huge swap cluster will only be split if the PMD swap mapping count is 0. Otherwise, we will keep it as the huge swap cluster. So that we can swapin a THP as a whole later. Signed-off-by: "Huang, Ying" Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Michal Hocko Cc: Johannes Weiner Cc: Shaohua Li Cc: Hugh Dickins Cc: Minchan Kim Cc: Rik van Riel Cc: Dave Hansen Cc: Naoya Horiguchi Cc: Zi Yan --- mm/swapfile.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index 7e1c5082d326..ed1fec275d2f 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -514,6 +514,18 @@ static void dec_cluster_info_page(struct swap_info_struct *p, free_cluster(p, idx); } +#ifdef CONFIG_THP_SWAP +static inline int cluster_swapcount(struct swap_cluster_info *ci) +{ + if (!ci || !cluster_is_huge(ci)) + return 0; + + return cluster_count(ci) - SWAPFILE_CLUSTER; +} +#else +#define cluster_swapcount(ci) 0 +#endif + /* * It's possible scan_swap_map() uses a free cluster in the middle of free * cluster list. Avoiding such abuse to avoid list corruption. @@ -905,6 +917,7 @@ static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) struct swap_cluster_info *ci; ci = lock_cluster(si, offset); + memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); cluster_set_count_flag(ci, 0, 0); free_cluster(si, idx); unlock_cluster(ci); @@ -1288,24 +1301,30 @@ static void swapcache_free_cluster(swp_entry_t entry) ci = lock_cluster(si, offset); VM_BUG_ON(!cluster_is_huge(ci)); + VM_BUG_ON(!is_cluster_offset(offset)); + VM_BUG_ON(cluster_count(ci) < SWAPFILE_CLUSTER); map = si->swap_map + offset; - for (i = 0; i < SWAPFILE_CLUSTER; i++) { - val = map[i]; - VM_BUG_ON(!(val & SWAP_HAS_CACHE)); - if (val == SWAP_HAS_CACHE) - free_entries++; + if (!cluster_swapcount(ci)) { + for (i = 0; i < SWAPFILE_CLUSTER; i++) { + val = map[i]; + VM_BUG_ON(!(val & SWAP_HAS_CACHE)); + if (val == SWAP_HAS_CACHE) + free_entries++; + } + if (free_entries != SWAPFILE_CLUSTER) + cluster_clear_huge(ci); } if (!free_entries) { - for (i = 0; i < SWAPFILE_CLUSTER; i++) - map[i] &= ~SWAP_HAS_CACHE; + for (i = 0; i < SWAPFILE_CLUSTER; i++) { + val = map[i]; + VM_BUG_ON(!(val & SWAP_HAS_CACHE) || + val == SWAP_HAS_CACHE); + map[i] = val & ~SWAP_HAS_CACHE; + } } - cluster_clear_huge(ci); unlock_cluster(ci); 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); -- 2.16.1