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Date: Fri, 21 Aug 2009 10:47:36 +0800 From: Amerigo Wang <xiyou.wangcong@...il.com> To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Cc: Amerigo Wang <xiyou.wangcong@...il.com>, Amerigo Wang <amwang@...hat.com>, "Eric W. Biederman" <ebiederm@...ssion.com>, linux-kernel@...r.kernel.org, tony.luck@...el.com, linux-ia64@...r.kernel.org, linux-mm@...ck.org, Neil Horman <nhorman@...hat.com>, Andi Kleen <andi@...stfloor.org>, akpm@...ux-foundation.org, bernhard.walle@....de, Fenghua Yu <fenghua.yu@...el.com>, Ingo Molnar <mingo@...e.hu>, Anton Vorontsov <avorontsov@...mvista.com> Subject: Re: [Patch 8/8] kexec: allow to shrink reserved memory On Fri, Aug 21, 2009 at 11:03:09AM +0900, KAMEZAWA Hiroyuki wrote: >On Fri, 21 Aug 2009 09:59:27 +0800 >Amerigo Wang <xiyou.wangcong@...il.com> 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 <amwang@...hat.com> 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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