On Mon, Jun 11, 2012 at 09:17:51AM +0900, Minchan Kim wrote: >d179e84ba fixed the problem[1] in vmscan.c but same problem is here. >Let's fix it. > >[1] http://comments.gmane.org/gmane.linux.kernel.mm/65844 > >I copy and paste d179e84ba's contents for description. > >"It is unsafe to run page_count during the physical pfn scan because >compound_head could trip on a dangling pointer when reading >page->first_page if the compound page is being freed by another CPU." > >Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> >Cc: Mel Gorman <mgorman@xxxxxxx> >Cc: Michal Hocko <mhocko@xxxxxxx> >Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> >Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> >--- > mm/page_alloc.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > >diff --git a/mm/page_alloc.c b/mm/page_alloc.c >index 266f267..019c4fe 100644 >--- a/mm/page_alloc.c >+++ b/mm/page_alloc.c >@@ -5496,7 +5496,11 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count) > continue; > > page = pfn_to_page(check); >- if (!page_count(page)) { >+ /* >+ * We can't use page_count withou pin a page ^ without >+ * because another CPU can free compound page. >+ */ >+ if (!atomic_read(&page->_count)) { > if (PageBuddy(page)) > iter += (1 << page_order(page)) - 1; > continue; >-- >1.7.9.5 > >-- >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> -- 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>