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mm: fix-up zone present pages

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I think zone->present_pages indicates pages that buddy system can management,
it should be:

	zone->present_pages = spanned pages - absent pages - bootmem pages,

but is now:
	zone->present_pages = spanned pages - absent pages - memmap pages.

spanned pages: total size, including holes.
absent pages: holes.
bootmem pages: pages used in system boot, managed by bootmem allocator.
memmap pages: pages used by page structs.

This may cause zone->present_pages less than it should be.  For example,
numa node 1 has ZONE_NORMAL and ZONE_MOVABLE, it's memmap and other
bootmem will be allocated from ZONE_MOVABLE, so ZONE_NORMAL's
present_pages should be spanned pages - absent pages, but now it also
minus memmap pages(free_area_init_core), which are actually allocated from
ZONE_MOVABLE.  When offlining all memory of a zone, this will cause
zone->present_pages less than 0, because present_pages is unsigned long
type, it is actually a very large integer, it indirectly caused
zone->watermark[WMARK_MIN] becomes a large
integer(setup_per_zone_wmarks()), than cause totalreserve_pages become a
large integer(calculate_totalreserve_pages()), and finally cause memory
allocating failure when fork process(__vm_enough_memory()).

[root@localhost ~]# dmesg
-bash: fork: Cannot allocate memory

I think the bug described in

  http://marc.info/?l=linux-mm&m=134502182714186&w=2

is also caused by wrong zone present pages.

This patch intends to fix-up zone->present_pages when memory are freed to
buddy system on x86_64 and IA64 platforms.

Signed-off-by: Jianguo Wu <[email protected]>
Signed-off-by: Jiang Liu <[email protected]>
Reported-by: Petr Tesarik <[email protected]>
Tested-by: Petr Tesarik <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Jianguo Wu 2012-10-08 16:33:06 -07:00 • committed by Linus Torvalds
commit 7f1290f2f2
6 changed files with 58 additions and 1 deletions
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10
mm/bootmem.c
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@ -198,6 +198,8 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
int order = ilog2(BITS_PER_LONG);
__free_pages_bootmem(pfn_to_page(start), order);
fixup_zone_present_pages(page_to_nid(pfn_to_page(start)),
start, start + BITS_PER_LONG);
count += BITS_PER_LONG;
start += BITS_PER_LONG;
} else {
@ -208,6 +210,9 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
if (vec & 1) {
page = pfn_to_page(start + off);
__free_pages_bootmem(page, 0);
fixup_zone_present_pages(
page_to_nid(page),
start + off, start + off + 1);
count++;
}
vec >>= 1;
@ -221,8 +226,11 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
pages = bdata->node_low_pfn - bdata->node_min_pfn;
pages = bootmem_bootmap_pages(pages);
count += pages;
while (pages--)
while (pages--) {
fixup_zone_present_pages(page_to_nid(page),
page_to_pfn(page), page_to_pfn(page) + 1);
__free_pages_bootmem(page++, 0);
}
bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);