Re: balloon question

["Jan Beulich" <jbeulich@novell.com>]

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>But I think it's prefereable to take the following loop from 
>i386/mm/init-xen.c and put it in x86/64's mem_init() somewhere:
>  for (i = ...->nr_pages; i < max_pfn; i++) {
>      ClearPageReserved(...);
>      set_page_count(..., 1);
>   }

Did you deliberately leave out the increment of totalram_pages that is in
i386's respective loop? I have to admit that I can't see why i386 is doing
that, but for symmetry I added it to x86-64's loop, too (balloon_init()
re-writes the variable anyway).

>That'll allow any architecture to reserve stuff beyond ->nr_pages 
>without breaking the balloon driver. Could you try adding the above 
>code and see how it works out?

Works out as expected (i.e. balloon now contains all the extra pages).
Patch attached.

Jan

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Index: head-2006-06-07/arch/x86_64/mm/init-xen.c
===================================================================
--- head-2006-06-07.orig/arch/x86_64/mm/init-xen.c	2006-06-09 10:16:34.000000000 +0200
+++ head-2006-06-07/arch/x86_64/mm/init-xen.c	2006-06-09 10:25:03.000000000 +0200
@@ -882,6 +882,7 @@ static struct kcore_list kcore_mem, kcor
 void __init mem_init(void)
 {
 	long codesize, reservedpages, datasize, initsize;
+	unsigned long pfn;
 
 	contiguous_bitmap = alloc_bootmem_low_pages(
 		(end_pfn + 2*BITS_PER_LONG) >> 3);
@@ -910,6 +911,12 @@ void __init mem_init(void)
 #else
 	totalram_pages = free_all_bootmem();
 #endif
+	/* XEN: init and count pages outside initial allocation. */
+	for (pfn = xen_start_info->nr_pages; pfn < max_pfn; pfn++) {
+		ClearPageReserved(&mem_map[pfn]);
+		set_page_count(&mem_map[pfn], 1);
+		totalram_pages++;
+	}
 	reservedpages = end_pfn - totalram_pages - e820_hole_size(0, end_pfn);
 
 	after_bootmem = 1;

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