On Thu, May 25, 2017 at 03:46:23PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > > The patch titled > Subject: mm/migrate: fix refcount handling when !hugepage_migration_supported() > has been added to the -mm tree. Its filename is > mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2.patch > > This patch should soon appear at > http://ozlabs.org/~akpm/mmots/broken-out/mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2.patch > and later at > http://ozlabs.org/~akpm/mmotm/broken-out/mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2.patch > > Before you just go and hit "reply", please: > a) Consider who else should be cc'ed > b) Prefer to cc a suitable mailing list as well > c) Ideally: find the original patch on the mailing list and do a > reply-to-all to that, adding suitable additional cc's > > *** Remember to use Documentation/SubmitChecklist when testing your code *** > > The -mm tree is included into linux-next and is updated > there every 3-4 working days > > ------------------------------------------------------ > From: Punit Agrawal <punit.agrawal@xxxxxxx> > Subject: mm/migrate: fix refcount handling when !hugepage_migration_supported() > > On failing to migrate a page, soft_offline_huge_page() performs the > necessary update to the hugepage ref-count. When > !hugepage_migration_supported() , unmap_and_move_hugepage() also > decrements the page ref-count for the hugepage. The combined behaviour > leaves the ref-count in an inconsistent state. > > This leads to soft lockups when running the overcommitted hugepage test > from mce-tests suite. > > Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000 > soft offline: 0x83ed600: migration failed 1, type > 1fffc00000008008 (uptodate|head) > INFO: rcu_preempt detected stalls on CPUs/tasks: > Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715 > (detected by 7, t=5254 jiffies, g=963, c=962, q=321) > thugetlb_overco R running task 0 2715 2685 0x00000008 > Call trace: > [<ffff000008089f90>] dump_backtrace+0x0/0x268 > [<ffff00000808a2d4>] show_stack+0x24/0x30 > [<ffff000008100d34>] sched_show_task+0x134/0x180 > [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c > [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08 > [<ffff000008143a3c>] update_process_times+0x34/0x60 > [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70 > [<ffff00000815516c>] tick_sched_timer+0x4c/0x98 > [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300 > [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228 > [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50 > [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290 > [<ffff0000081297fc>] generic_handle_irq+0x34/0x50 > [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0 > [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0 > > Address this by changing the putback_active_hugepage() in > soft_offline_huge_page() to putback_movable_pages(). > > Link: http://lkml.kernel.org/r/20170525135146.32011-1-punit.agrawal@xxxxxxx > Reported-by: Manoj Iyer <manoj.iyer@xxxxxxxxxxxxx> > Tested-by: Manoj Iyer <manoj.iyer@xxxxxxxxxxxxx> > Suggested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > Cc: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > Cc: Christoph Lameter <cl@xxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> [3.14+] > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > mm/memory-failure.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff -puN mm/memory-failure.c~mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2 mm/memory-failure.c > --- a/mm/memory-failure.c~mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2 > +++ a/mm/memory-failure.c > @@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct > * only one hugepage pointed to by hpage, so we need not > * run through the pagelist here. > */ Hi Andrew, I just noticed that the comment above this becomes obsolete with this change, so could you remove it? (please fold it to this patch.) @@ -1649,11 +1649,6 @@ static int soft_offline_huge_page(struct page *page, int flags) if (ret) { pr_info("soft offline: %#lx: migration failed %d, type %lx (%pGp)\n", pfn, ret, page->flags, &page->flags); - /* - * We know that soft_offline_huge_page() tries to migrate - * only one hugepage pointed to by hpage, so we need not - * run through the pagelist here. - */ if (!list_empty(&pagelist)) putback_movable_pages(&pagelist); if (ret > 0) Thanks, Naoya Horiguchi > - putback_active_hugepage(hpage); > + if (!list_empty(&pagelist)) > + putback_movable_pages(&pagelist); > if (ret > 0) > ret = -EIO; > } else { > _ > > Patches currently in -mm which might be from punit.agrawal@xxxxxxx are > > mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported-v2.patch > mm-gup-ensure-real-head-page-is-ref-counted-when-using-hugepages.patch > mm-hugetlb-add-size-parameter-to-huge_pte_offset.patch > mm-hugetlb-allow-architectures-to-override-huge_pte_clear.patch > mm-hugetlb-introduce-set_huge_swap_pte_at-helper.patch > mm-hugetlb-introduce-set_huge_swap_pte_at-helper-v4.patch > mm-hugetlb-introduce-set_huge_swap_pte_at-helper-v41.patch > mm-rmap-use-correct-helper-when-poisoning-hugepages.patch > >