Messages in this thread | | | Date | Fri, 28 Mar 2008 11:33:12 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 2 of 4] hotplug-memory: adding non-section-aligned memory is bad |
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On Thu, 27 Mar 2008 19:13:20 -0700 Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> >> Because, firmware may occupy some area in the section. > >> Firmware must exclude those area to notify kernel. So, E820, EFI, > >> or _CRS of ACPI may return not aligned address and size. > >> register_memory_resource() and walk_memory_resource() are to skip > >> them silently. This is intended. > >> > >> > > Ah, ok. sorry. > > > > Jeremy, I think you can check whether you have 'struct page' or not by > > pfn_valid(). > > > > If pfn_valid() == false, you should call add_memory() and create > > a section/mem_map. If pfn_valid() == true, you should just remove > > PG_reserved bit in mem_map by online_page(). > > OK. Would that ever be necessary if I explicitly align my start and size? > Maybe no. but be carefull not to register resource in overlapped manner. (I wrote online_page() in above, but online_pages() is maybe better. It does all what you want.)
Start/Size are automatically alined to section in __add_pages().
See below. == 110 int __add_pages(struct zone *zone, unsigned long phys_start_pfn, 111 unsigned long nr_pages) 112 { 113 unsigned long i; 114 int err = 0; 115 int start_sec, end_sec; 116 /* during initialize mem_map, align hot-added range to section */ 117 start_sec = pfn_to_section_nr(phys_start_pfn); 118 end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1); ==
And online_pages(), which onlines pages in [pfn, pfn + size), will see registerred resources within [pfn, pfn + size). == 184 int online_pages(unsigned long pfn, unsigned long nr_pages) <snip> 227 walk_memory_resource(pfn, nr_pages, &onlined_pages, 228 online_pages_range); ==
One of my concern is how-to-handle sysfs status in this case.
Another concerns is, currently, I think no one tried to online a section twice to online reserved pages in a section. so, you may see bug. For example, mem_notify() in online_pages() will be called several times against a section.
Thanks, -Kame
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