From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 9B43B6B003D for ; Fri, 8 Jan 2010 09:06:37 -0500 (EST) Subject: Re: + hugetlb-fix-section-mismatch-warning-in-hugetlbc.patch added to -mm tree From: Lee Schermerhorn In-Reply-To: References: <201001072218.o07MIPNm020870@imap1.linux-foundation.org> <20100107143651.2fa73662.randy.dunlap@oracle.com> Content-Type: text/plain Date: Fri, 08 Jan 2010 09:06:09 -0500 Message-Id: <1262959569.24795.22.camel@useless.americas.hpqcorp.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Rakib Mullick Cc: Randy Dunlap , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org List-ID: On Fri, 2010-01-08 at 12:34 +0600, Rakib Mullick wrote: > On 1/8/10, Randy Dunlap wrote: > > Hi, > > > > Hi, > > > > If so, then hugetlb_register_node() could be called at any time > > (like after system init), and it would then call > > hugetlb_sysfs_add_hstate(), which would be bad. > > > But - hugetlb_register_node is only called from hugetlb_register_all_nodes. No, hugetlb_register_node() is also called from the similarly named function in drivers/base/node.c. mm/hugetlb.c registers its version of "hugetlb_register_node()" at start up for use at node hotplug. See register_hugetlbfs_with_node() in node.c and its use in hugetlb.c. We had to do it this way because node.c is part of the base kernel and hugetlb support can be built as a module. All sysfs node kobjs have been registered by the time hugetlb inits, so hugetlb registers the nodes' hstate attributes when it initializes. However, when a node is hotplugged later, the node driver calls into hugetlb to register the attributes. So, we need to keep mm/hugetlb.c:hugetlb_register_node() around during run time when mem/node hot-plug is supported. Lee > The call sequence is : > hugetlb_init ---------------> was __init > \-> hugetlb_register_all_nodes ----> we make it __init > \-> hugetlb_register_node > ---> we make it __init > \-> > hugetlb_sysfs_add_hstate -> this was __init > > Above all happens in __init context. So - hugetlb_register_node is > called only at > system init. But I don't think __init is used for hotplug support, for > proper hotplug > support we might use __meminit. > > And register_hugetlbfs_with_node is called from hugetlb_un/register_node. > But hugetlb_unregister_node doesn't use callback function. It's not referencing > hugetlb_sysfs_add_hstate(). So - it's safe. Unless I'm not missing > anything, too. > > thanks, > > > Thanks. > > --- > > > > ~Randy > > > > -- > 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 -- 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