On Mon 01-04-13 10:43:14, Aneesh Kumar K.V wrote: > Michal Hocko <mhocko@xxxxxxx> writes: > > > On Tue 26-03-13 16:59:40, Aneesh Kumar K.V wrote: > >> Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> writes: > > [...] > >> > diff --git v3.9-rc3.orig/mm/memory-failure.c v3.9-rc3/mm/memory-failure.c > >> > index df0694c..4e01082 100644 > >> > --- v3.9-rc3.orig/mm/memory-failure.c > >> > +++ v3.9-rc3/mm/memory-failure.c > >> > @@ -1467,6 +1467,7 @@ static int soft_offline_huge_page(struct page *page, int flags) > >> > int ret; > >> > unsigned long pfn = page_to_pfn(page); > >> > struct page *hpage = compound_head(page); > >> > + LIST_HEAD(pagelist); > >> > > >> > /* > >> > * This double-check of PageHWPoison is to avoid the race with > >> > @@ -1482,12 +1483,20 @@ static int soft_offline_huge_page(struct page *page, int flags) > >> > unlock_page(hpage); > >> > > >> > /* Keep page count to indicate a given hugepage is isolated. */ > >> > - ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL, > >> > - MIGRATE_SYNC); > >> > - put_page(hpage); > >> > + list_move(&hpage->lru, &pagelist); > >> > >> we use hpage->lru to add the hpage to h->hugepage_activelist. This will > >> break a hugetlb cgroup removal isn't it ? > > > > This particular part will not break removal because > > hugetlb_cgroup_css_offline loops until hugetlb_cgroup_have_usage is 0. > > > > But we still need to hold hugetlb_lock around that right ? Right. Racing hugetlb_cgroup_move_parent and hugetlb_cgroup_migrate could lead to newpage pointing to NULL cgroup. That could be fixed by checking old page cgroup for NULL inside hugetlb_lock and using list_for_each_safe in hugetlb_cgroup_css_offline no? -- Michal Hocko SUSE Labs -- 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>