From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 270C06B0062 for ; Fri, 21 Aug 2009 18:02:10 -0400 (EDT) Received: by rv-out-0708.google.com with SMTP id l33so284102rvb.26 for ; Fri, 21 Aug 2009 15:02:09 -0700 (PDT) Date: Fri, 21 Aug 2009 10:47:36 +0800 From: Amerigo Wang Subject: Re: [Patch 8/8] kexec: allow to shrink reserved memory Message-ID: <20090821024736.GB4447@cr0.nay.redhat.com> References: <4A8A4ABB.70003@redhat.com> <20090818172552.779d0768.kamezawa.hiroyu@jp.fujitsu.com> <4A8A83F4.6010408@redhat.com> <20090819085703.ccf9992a.kamezawa.hiroyu@jp.fujitsu.com> <4A8B6649.3080103@redhat.com> <20090819171346.aadfeb2c.kamezawa.hiroyu@jp.fujitsu.com> <4A8D144C.5050005@redhat.com> <20090821093452.ead96b2d.kamezawa.hiroyu@jp.fujitsu.com> <20090821015927.GA4447@cr0.nay.redhat.com> <20090821110309.2d5ffb62.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090821110309.2d5ffb62.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Amerigo Wang , Amerigo Wang , "Eric W. Biederman" , linux-kernel@vger.kernel.org, tony.luck@intel.com, linux-ia64@vger.kernel.org, linux-mm@kvack.org, Neil Horman , Andi Kleen , akpm@linux-foundation.org, bernhard.walle@gmx.de, Fenghua Yu , Ingo Molnar , Anton Vorontsov List-ID: On Fri, Aug 21, 2009 at 11:03:09AM +0900, KAMEZAWA Hiroyuki wrote: >On Fri, 21 Aug 2009 09:59:27 +0800 >Amerigo Wang wrote: > >> On Fri, Aug 21, 2009 at 09:34:52AM +0900, KAMEZAWA Hiroyuki wrote: >> >On Thu, 20 Aug 2009 17:15:56 +0800 >> >Amerigo Wang wrote: >> > >> >> > The, problem is whether memmap is there or not. That's all. >> >> > plz see init sequence and check there are memmap. >> >> > If memory-for-crash is obtained via bootmem, >> >> > Don't you try to free memory hole ? >> >> > >> >> >> >> Hi, >> >> >> >> It looks like that mem_map has 'struct page' for the reserved memory, I >> >> checked my "early_node_map[] active PFN ranges" output, the reserved >> >> memory area for crash kernel is right in one range. Am I missing >> >> something here? >> >> >> >> I don't know why that oops comes out, maybe because of no PTE for thoese >> >> pages? >> >> >> >Hmm ? Could you show me the code you use ? >> >> (Sorry that I reply to you with my gmail, my work email can't send out >> this message, probably because one of the destinations is broken... >> I am the same person, don't be confused. :-) >> >> Sure. Below is it: >> >> + for (addr = end + 1; addr < crashk_res.end; addr += PAGE_SIZE) { >> + printk(KERN_DEBUG "PFN is valid? %d\n", pfn_valid(addr>>PAGE_SHIFT)); >> + ClearPageReserved(virt_to_page(addr)); >> + init_page_count(virt_to_page(addr)); >> + free_page(addr); >> + totalram_pages++; >> + } >> >> >> pfn_valid() returns 1, and oops happens at ClearPageReserved(). >> ('addr' is right between crashk_res.start and crashk_res.end) > >Confused, > if pfn_valid(addr >> PAGE_SHIFT) == true > >you should do > ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT)); > >because addr is physical address, not virtual. >I guess crashk_res.end is physical address.... Excellent! You are right! In fact, when I read the kexec code at the first time, I thought 'crashk_res' should hold physical address too, but after reading more code I dropped that idea, so I am wrong. :-/ I will resend the whole patchset soon. It works now! Thanks for your nice help, Hiroyuki! -- 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