From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id B83258E0038 for ; Tue, 8 Jan 2019 14:32:18 -0500 (EST) Received: by mail-pg1-f200.google.com with SMTP id d3so2590728pgv.23 for ; Tue, 08 Jan 2019 11:32:18 -0800 (PST) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id d92si1065322pld.45.2019.01.08.11.32.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Jan 2019 11:32:17 -0800 (PST) From: Sasha Levin Subject: [PATCH AUTOSEL 4.19 95/97] mm/swap: use nr_node_ids for avail_lists in swap_info_struct Date: Tue, 8 Jan 2019 14:29:44 -0500 Message-Id: <20190108192949.122407-95-sashal@kernel.org> In-Reply-To: <20190108192949.122407-1-sashal@kernel.org> References: <20190108192949.122407-1-sashal@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Aaron Lu , Vasily Averin , Huang Ying , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm@kvack.org From: Aaron Lu [ Upstream commit 66f71da9dd38af17dc17209cdde7987d4679a699 ] Since a2468cc9bfdf ("swap: choose swap device according to numa node"), avail_lists field of swap_info_struct is changed to an array with MAX_NUMNODES elements. This made swap_info_struct size increased to 40KiB and needs an order-4 page to hold it. This is not optimal in that: 1 Most systems have way less than MAX_NUMNODES(1024) nodes so it is a waste of memory; 2 It could cause swapon failure if the swap device is swapped on after system has been running for a while, due to no order-4 page is available as pointed out by Vasily Averin. Solve the above two issues by using nr_node_ids(which is the actual possible node number the running system has) for avail_lists instead of MAX_NUMNODES. nr_node_ids is unknown at compile time so can't be directly used when declaring this array. What I did here is to declare avail_lists as zero element array and allocate space for it when allocating space for swap_info_struct. The reason why keep using array but not pointer is plist_for_each_entry needs the field to be part of the struct, so pointer will not work. This patch is on top of Vasily Averin's fix commit. I think the use of kvzalloc for swap_info_struct is still needed in case nr_node_ids is really big on some systems. Link: http://lkml.kernel.org/r/20181115083847.GA11129@intel.com Signed-off-by: Aaron Lu Reviewed-by: Andrew Morton Acked-by: Michal Hocko Cc: Vasily Averin Cc: Huang Ying Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- include/linux/swap.h | 11 ++++++++++- mm/swapfile.c | 3 ++- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 8e2c11e692ba..77221c16733a 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -232,7 +232,6 @@ struct swap_info_struct { unsigned long flags; /* SWP_USED etc: see above */ signed short prio; /* swap priority of this type */ struct plist_node list; /* entry in swap_active_head */ - struct plist_node avail_lists[MAX_NUMNODES];/* entry in swap_avail_heads */ signed char type; /* strange name for an index */ unsigned int max; /* extent of the swap_map */ unsigned char *swap_map; /* vmalloc'ed array of usage counts */ @@ -273,6 +272,16 @@ struct swap_info_struct { */ struct work_struct discard_work; /* discard worker */ struct swap_cluster_list discard_clusters; /* discard clusters list */ + struct plist_node avail_lists[0]; /* + * entries in swap_avail_heads, one + * entry per node. + * Must be last as the number of the + * array is nr_node_ids, which is not + * a fixed value so have to allocate + * dynamically. + * And it has to be an array so that + * plist_for_each_* can work. + */ }; #ifdef CONFIG_64BIT diff --git a/mm/swapfile.c b/mm/swapfile.c index 8810a6d7d67f..08ba73eaaba2 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2819,8 +2819,9 @@ static struct swap_info_struct *alloc_swap_info(void) struct swap_info_struct *p; unsigned int type; int i; + int size = sizeof(*p) + nr_node_ids * sizeof(struct plist_node); - p = kvzalloc(sizeof(*p), GFP_KERNEL); + p = kvzalloc(size, GFP_KERNEL); if (!p) return ERR_PTR(-ENOMEM); -- 2.19.1