On Tue, 18 Mar 2014 22:29:39 -0400 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote: > We have a race where we try to migrate an invalid page, resulting in > hitting VM_BUG_ON_PAGE in isolate_huge_page(). > queue_pages_hugetlb() is OK to fail, so let's check !PageHeadHuge to keep > invalid hugepage from queuing. > > .. > > --- v3.14-rc7-mmotm-2014-03-18-16-37.orig/mm/mempolicy.c > +++ v3.14-rc7-mmotm-2014-03-18-16-37/mm/mempolicy.c > @@ -530,6 +530,17 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long addr, > if (!pte_present(entry)) > return 0; > page = pte_page(entry); > + > + /* > + * Trinity found that page could be a non-hugepage. This is an > + * unexpected behavior, but it's not clear how this problem happens. > + * So let's simply skip such corner case. Page migration can often > + * fail for various reasons, so it's ok to just skip the address > + * unsuitable to hugepage migration. > + */ > + if (!PageHeadHuge(page)) > + return 0; > + Whoa, we won't be doing this thanks. The day we resort to this sort of thing is the day we revert to the 2.2.26 VM. I suppose I'd be OK with putting if (WARN_ON(!PageHeadHuge(page))) return 0; in there as a temporary be-kind-to-testers thing, but we must get a full understanding of what's happening in there. Was this problem caused by or exposed by the pagetable walker patches? -- 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>