From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx179.postini.com [74.125.245.179]) by kanga.kvack.org (Postfix) with SMTP id 641E16B0027 for ; Wed, 17 Apr 2013 00:47:21 -0400 (EDT) Received: by mail-pb0-f54.google.com with SMTP id xa7so674311pbc.13 for ; Tue, 16 Apr 2013 21:47:20 -0700 (PDT) Date: Tue, 16 Apr 2013 21:47:18 -0700 (PDT) From: David Rientjes Subject: Re: [Bug fix PATCH v3] Reusing a resource structure allocated by bootmem In-Reply-To: <516E2305.3060705@jp.fujitsu.com> Message-ID: References: <516DEC34.7040008@jp.fujitsu.com> <516E2305.3060705@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Yasuaki Ishimatsu Cc: Andrew Morton , toshi.kani@hp.com, linuxram@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Wed, 17 Apr 2013, Yasuaki Ishimatsu wrote: > > Why not simply do what generic sparsemem support does by testing > > PageSlab(virt_to_head_page(res)) and calling kfree() if true and freeing > > back to bootmem if false? This should be like a five line patch. > > Is your explanation about free_section_usemap()? > If so, I don't think we can release resource structure like > free_section_usemap(). Right, you can't release it like free_section_usemap(), but you're free to test for PageSlab(virt_to_head_page(res)) in kernel/resource.c. > In your explanation case, memmap can be released by put_page_bootmem() in > free_map_bootmem() since all pages of memmap is used only for memmap. > But if my understanding is correct, a page of released resource structure > contain other purpose objects allocated by bootmem. So we cannot > release resource structure like free_section_usemap(). > I'm thinking it would be much easier to just suppress the kfree() if !PageSlab. If you can free an entire page with free_bootmem_late(), that would be great, but I'm thinking that will take more work than it's worth. It seems fine to just do free_bootmem() and leave those pages as reserved. How much memory are we talking about? -- 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