From: Fengguang Wu <fengguang.wu@intel.com>
Subject: [RFC][PATCH v2 21/21] mm/vmscan.c: shrink anon list if can migrate to PMEM
Date: Wed, 26 Dec 2018 21:15:07 +0800
Message-ID: <20181226133352.303666865@intel.com>
References: <20181226131446.330864849@intel.com>
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Cc: Linux Memory Management List <linux-mm@kvack.org>,
        Fengguang Wu <fengguang.wu@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
cc: kvm@vger.kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>
cc: Fan Du <fan.du@intel.com>
cc: Yao Yuan <yuan.yao@intel.com>
cc: Peng Dong <dongx.peng@intel.com>
cc: Huang Ying <ying.huang@intel.com>
CC: Liu Jingqi <jingqi.liu@intel.com>
cc: Dong Eddie <eddie.dong@intel.com>
cc: Dave Hansen <dave.hansen@intel.com>
cc: Zhang Yi <yi.z.zhang@linux.intel.com>
cc: Dan Williams <dan.j.williams@intel.com>
Content-Disposition: inline; filename=0013-vmscan-disable-0-swap-space-optimization.patch
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

Fix OOM by making in-kernel DRAM=>PMEM migration reachable.

Here we assume these 2 possible demotion paths:
- DRAM migrate to PMEM
- PMEM to swap device

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
 mm/vmscan.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- linux.orig/mm/vmscan.c	2018-12-23 20:38:44.310446223 +0800
+++ linux/mm/vmscan.c	2018-12-23 20:38:44.306446146 +0800
@@ -2259,7 +2259,7 @@ static bool inactive_list_is_low(struct
 	 * If we don't have swap space, anonymous page deactivation
 	 * is pointless.
 	 */
-	if (!file && !total_swap_pages)
+	if (!file && (is_node_pmem(pgdat->node_id) && !total_swap_pages))
 		return false;
 
 	inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx);
@@ -2340,7 +2340,8 @@ static void get_scan_count(struct lruvec
 	enum lru_list lru;
 
 	/* If we have no swap space, do not bother scanning anon pages. */
-	if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {
+	if (is_node_pmem(pgdat->node_id) &&
+	    (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0)) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}