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sparsemem: record when a section has a valid mem_map

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We have flags to indicate whether a section actually has a valid mem_map
associated with it.  This is never set and we rely solely on the present bit
to indicate a section is valid.  By definition a section is not valid if it
has no mem_map and there is a window during init where the present bit is set
but there is no mem_map, during which pfn_valid() will return true
incorrectly.

Use the existing SECTION_HAS_MEM_MAP flag to indicate the presence of a valid
mem_map.  Switch valid_section{,_nr} and pfn_valid() to this bit.  Add a new
present_section{,_nr} and pfn_present() interfaces for those users who care to
know that a section is going to be valid.

[akpm@linux-foundation.org: coding-syle fixes]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Whitcroft
2007-10-16 01:24:11 -07:00
committed by Linus Torvalds
parent cd881a6b22
commit 540557b943
3 changed files with 22 additions and 9 deletions
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9
mm/sparse.c
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@@ -176,7 +176,7 @@ unsigned long __init node_memmap_size_bytes(int nid, unsigned long start_pfn,
if (nid != early_pfn_to_nid(pfn))
continue;
if (pfn_valid(pfn))
if (pfn_present(pfn))
nr_pages += PAGES_PER_SECTION;
}
@@ -206,11 +206,12 @@ struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pn
static int __meminit sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map)
{
if (!valid_section(ms))
if (!present_section(ms))
return -EINVAL;
ms->section_mem_map &= ~SECTION_MAP_MASK;
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
SECTION_HAS_MEM_MAP;
return 1;
}
@@ -256,7 +257,7 @@ void __init sparse_init(void)
struct page *map;
for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) {
if (!valid_section_nr(pnum))
if (!present_section_nr(pnum))
continue;
map = sparse_early_mem_map_alloc(pnum);