From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752164AbdIIX1H (ORCPT ); Sat, 9 Sep 2017 19:27:07 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:43076 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751822AbdIIXCS (ORCPT ); Sat, 9 Sep 2017 19:02:18 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Torvalds" , "Mel Gorman" , "Manoj Iyer" , "Wanpeng Li" , "Joonsoo Kim" , "Punit Agrawal" , "Naoya Horiguchi" , "Christoph Lameter" Date: Sat, 09 Sep 2017 22:47:14 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 111/233] mm/migrate: fix refcount handling when !hugepage_migration_supported() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.48-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Punit Agrawal commit 30809f559a0d348c2dfd7ab05e9a451e2384962e upstream. On failing to migrate a page, soft_offline_huge_page() performs the necessary update to the hugepage ref-count. But 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: dump_backtrace+0x0/0x268 show_stack+0x24/0x30 sched_show_task+0x134/0x180 rcu_print_detail_task_stall_rnp+0x54/0x7c rcu_check_callbacks+0xa74/0xb08 update_process_times+0x34/0x60 tick_sched_handle.isra.7+0x38/0x70 tick_sched_timer+0x4c/0x98 __hrtimer_run_queues+0xc0/0x300 hrtimer_interrupt+0xac/0x228 arch_timer_handler_phys+0x3c/0x50 handle_percpu_devid_irq+0x8c/0x290 generic_handle_irq+0x34/0x50 __handle_domain_irq+0x68/0xc0 gic_handle_irq+0x5c/0xb0 Address this by changing the putback_active_hugepage() in soft_offline_huge_page() to putback_movable_pages(). This only triggers on systems that enable memory failure handling (ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration (!ARCH_ENABLE_HUGEPAGE_MIGRATION). I imagine this wasn't triggered as there aren't many systems running this configuration. [akpm@linux-foundation.org: remove dead comment, per Naoya] Link: http://lkml.kernel.org/r/20170525135146.32011-1-punit.agrawal@arm.com Reported-by: Manoj Iyer Tested-by: Manoj Iyer Suggested-by: Naoya Horiguchi Signed-off-by: Punit Agrawal Cc: Joonsoo Kim Cc: Wanpeng Li Cc: Christoph Lameter Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- mm/memory-failure.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1551,12 +1551,8 @@ static int soft_offline_huge_page(struct if (ret) { pr_info("soft offline: %#lx: migration failed %d, type %lx\n", pfn, ret, 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. - */ - putback_active_hugepage(hpage); + if (!list_empty(&pagelist)) + putback_movable_pages(&pagelist); if (ret > 0) ret = -EIO; } else {