On Wed, Mar 23, 2016 at 03:47:46PM +0100, Vlastimil Babka wrote: > On 03/14/2016 08:31 AM, js1304@xxxxxxxxx wrote: > >From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > > >There is a system that node's pfn are overlapped like as following. > > > >-----pfn--------> > >N0 N1 N2 N0 N1 N2 > > > >Therefore, we need to care this overlapping when iterating pfn range. > > > >There are two places in vmstat.c that iterates pfn range and > >they don't consider this overlapping. Add it. > > > >Without this patch, above system could over count pageblock number > >on a zone. > > > >Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > >--- > > mm/vmstat.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > >diff --git a/mm/vmstat.c b/mm/vmstat.c > >index 5e43004..0a726e3 100644 > >--- a/mm/vmstat.c > >+++ b/mm/vmstat.c > >@@ -1010,6 +1010,9 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m, > > if (!memmap_valid_within(pfn, page, zone)) > > continue; > > The above already does this for each page within the block, but it's > guarded by CONFIG_ARCH_HAS_HOLES_MEMORYMODEL. I guess that's not the > case of your system, right? > > I guess your added check should go above this, though. Also what > about employing pageblock_pfn_to_page() here and in all other > applicable places, so it's unified and optimized by > zone->contiguous? Comment on memmap_valid_within() in mmzone.h says that page_zone() linkages could be broken in that system even if pfn_valid() returns true. So, we cannot do zone check before it. In fact, I wonder how that system works fine under the situation where there are many pfn interators which doesn't check memmap_valid_within(). I guess there may be enough constraint. Anyway, I think that it is another issue and would be revisited later. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>