From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx129.postini.com [74.125.245.129]) by kanga.kvack.org (Postfix) with SMTP id 8E2F96B003A for ; Tue, 5 Feb 2013 21:21:43 -0500 (EST) Message-ID: <5111BE09.2030509@cn.fujitsu.com> Date: Wed, 06 Feb 2013 10:20:57 +0800 From: Tang Chen MIME-Version: 1.0 Subject: Re: [PATCH 3/3] acpi, memory-hotplug: Support getting hotplug info from SRAT. References: <1359106929-3034-1-git-send-email-tangchen@cn.fujitsu.com> <1359106929-3034-4-git-send-email-tangchen@cn.fujitsu.com> <20130204152651.2bca8dba.akpm@linux-foundation.org> In-Reply-To: <20130204152651.2bca8dba.akpm@linux-foundation.org> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: jiang.liu@huawei.com, wujianguo@huawei.com, hpa@zytor.com, wency@cn.fujitsu.com, laijs@cn.fujitsu.com, linfeng@cn.fujitsu.com, yinghai@kernel.org, isimatu.yasuaki@jp.fujitsu.com, rob@landley.net, kosaki.motohiro@jp.fujitsu.com, minchan.kim@gmail.com, mgorman@suse.de, rientjes@google.com, guz.fnst@cn.fujitsu.com, rusty@rustcorp.com.au, lliubbo@gmail.com, jaegeuk.hanse@gmail.com, tony.luck@intel.com, glommer@parallels.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On 02/05/2013 07:26 AM, Andrew Morton wrote: > On Fri, 25 Jan 2013 17:42:09 +0800 > Tang Chen wrote: > >> We now provide an option for users who don't want to specify physical >> memory address in kernel commandline. >> >> /* >> * For movablemem_map=acpi: >> * >> * SRAT: |_____| |_____| |_________| |_________| ...... >> * node id: 0 1 1 2 >> * hotpluggable: n y y n >> * movablemem_map: |_____| |_________| >> * >> * Using movablemem_map, we can prevent memblock from allocating memory >> * on ZONE_MOVABLE at boot time. >> */ >> >> So user just specify movablemem_map=acpi, and the kernel will use hotpluggable >> info in SRAT to determine which memory ranges should be set as ZONE_MOVABLE. >> >> ... >> >> + if (!strncmp(p, "acpi", max(4, strlen(p)))) >> + movablemem_map.acpi = true; > > Generates a warning: > > mm/page_alloc.c: In function 'cmdline_parse_movablemem_map': > mm/page_alloc.c:5312: warning: comparison of distinct pointer types lacks a cast > > due to max(int, size_t). > > This is easily fixed, but the code looks rather pointless. If the > incoming string is supposed to be exactly "acpi" then use strcmp(). If > the incoming string must start with "acpi" then use strncmp(p, "acpi", 4). > > IOW, the max is unneeded? Hi Andrew, I think I made another mistake here. I meant to use min(4, strlen(p)) in case p is something like 'aaa' whose length is less then 4. But I mistook it with max(). But after I dig into strcmp() in the kernel, I think it is OK to use strcmp(). min() or max() is not needed. Thanks. :) > > -- > 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/ > -- 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