Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752303Ab2FRIZV (ORCPT ); Mon, 18 Jun 2012 04:25:21 -0400 Received: from mail-qc0-f174.google.com ([209.85.216.174]:60557 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751439Ab2FRIZS (ORCPT ); Mon, 18 Jun 2012 04:25:18 -0400 Message-ID: <4FDEE5EB.8040702@gmail.com> Date: Mon, 18 Jun 2012 04:25:15 -0400 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Minchan Kim CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kosaki.motohiro@gmail.com Subject: Re: [PATCH] trivial, memory hotplug: add kswapd_is_running() for better readability References: <4FD97718.6060008@kernel.org> <1339663776-196-1-git-send-email-jiang.liu@huawei.com> <4FDE8081.1070500@kernel.org> In-Reply-To: <4FDE8081.1070500@kernel.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2254 Lines: 67 (6/17/12 9:12 PM), Minchan Kim wrote: > On 06/17/2012 11:19 AM, David Rientjes wrote: > >> On Thu, 14 Jun 2012, Jiang Liu wrote: >> >>> diff --git a/include/linux/swap.h b/include/linux/swap.h >>> index c84ec68..36249d5 100644 >>> --- a/include/linux/swap.h >>> +++ b/include/linux/swap.h >>> @@ -301,6 +301,11 @@ static inline void scan_unevictable_unregister_node(struct node *node) >>> >>> extern int kswapd_run(int nid); >>> extern void kswapd_stop(int nid); >>> +static inline bool kswapd_is_running(int nid) >>> +{ >>> + return !!(NODE_DATA(nid)->kswapd); >>> +} >>> + >>> #ifdef CONFIG_CGROUP_MEM_RES_CTLR >>> extern int mem_cgroup_swappiness(struct mem_cgroup *mem); >>> #else >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 0d7e3ec..88e479d 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -522,7 +522,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages) >>> init_per_zone_wmark_min(); >>> >>> if (onlined_pages) { >>> - kswapd_run(zone_to_nid(zone)); >>> + if (!kswapd_is_running(zone_to_nid(zone))) >>> + kswapd_run(zone_to_nid(zone)); >>> node_set_state(zone_to_nid(zone), N_HIGH_MEMORY); >>> } >>> >>> diff --git a/mm/vmscan.c b/mm/vmscan.c >>> index 7585101..3dafdbe 100644 >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -2941,8 +2941,7 @@ int kswapd_run(int nid) >>> pg_data_t *pgdat = NODE_DATA(nid); >>> int ret = 0; >>> >>> - if (pgdat->kswapd) >>> - return 0; >>> + BUG_ON(pgdat->kswapd); >>> >>> pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid); >>> if (IS_ERR(pgdat->kswapd)) { >> >> This isn't better, there's no functional change and you've just added a >> second conditional for no reason and an unnecessary kswapd_is_running() >> function. > > Tend to agree. > Now that I think about it, it's enough to add comment. Ok, I'd like to handle this issue because now I have some mem-hotplug related tirivial fixes. So, to add one more patch is not big bother to me. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/