From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx187.postini.com [74.125.245.187]) by kanga.kvack.org (Postfix) with SMTP id 267056B003A for ; Mon, 13 May 2013 15:08:50 -0400 (EDT) Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 13 May 2013 15:08:49 -0400 Received: from d01relay05.pok.ibm.com (d01relay05.pok.ibm.com [9.56.227.237]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id 16E9CC90044 for ; Mon, 13 May 2013 15:08:46 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by d01relay05.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r4DJ8kQ2324496 for ; Mon, 13 May 2013 15:08:46 -0400 Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r4DJ8jHh014020 for ; Mon, 13 May 2013 15:08:46 -0400 From: Cody P Schafer Subject: [PATCH RESEND v3 02/11] mm/page_alloc: prevent concurrent updaters of pcp ->batch and ->high Date: Mon, 13 May 2013 12:08:14 -0700 Message-Id: <1368472103-3427-3-git-send-email-cody@linux.vnet.ibm.com> In-Reply-To: <1368472103-3427-1-git-send-email-cody@linux.vnet.ibm.com> References: <1368472103-3427-1-git-send-email-cody@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Gilad Ben-Yossef , Simon Jeons , KOSAKI Motohiro , Mel Gorman , Linux MM , LKML , Cody P Schafer Because we are going to rely upon a careful transision between old and new ->high and ->batch values using memory barriers and will remove stop_machine(), we need to prevent multiple updaters from interweaving their memory writes. Add a simple mutex to protect both update loops. Signed-off-by: Cody P Schafer --- mm/page_alloc.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9e556e6..cea883d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -65,6 +65,9 @@ #include #include "internal.h" +/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */ +static DEFINE_MUTEX(pcp_batch_high_lock); + #ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID DEFINE_PER_CPU(int, numa_node); EXPORT_PER_CPU_SYMBOL(numa_node); @@ -5555,6 +5558,8 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, ret = proc_dointvec_minmax(table, write, buffer, length, ppos); if (!write || (ret < 0)) return ret; + + mutex_lock(&pcp_batch_high_lock); for_each_populated_zone(zone) { for_each_possible_cpu(cpu) { unsigned long high; @@ -5563,6 +5568,7 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write, per_cpu_ptr(zone->pageset, cpu), high); } } + mutex_unlock(&pcp_batch_high_lock); return 0; } @@ -6076,7 +6082,9 @@ static int __meminit __zone_pcp_update(void *data) void __meminit zone_pcp_update(struct zone *zone) { + mutex_lock(&pcp_batch_high_lock); stop_machine(__zone_pcp_update, zone, NULL); + mutex_unlock(&pcp_batch_high_lock); } #endif -- 1.8.2.2 -- 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