From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S969573AbdEYNwC (ORCPT ); Thu, 25 May 2017 09:52:02 -0400 Received: from foss.arm.com ([217.140.101.70]:50328 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969231AbdEYNv7 (ORCPT ); Thu, 25 May 2017 09:51:59 -0400 From: Punit Agrawal To: Andrew Morton Cc: Punit Agrawal , will.deacon@arm.com, catalin.marinas@arm.com, manoj.iyer@canonical.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, tbaicar@codeaurora.org, timur@qti.qualcomm.com, n-horiguchi@ah.jp.nec.com, Joonsoo Kim , Wanpeng Li , Christoph Lameter , "# v3 . 14+" Subject: [PATCH v2] mm/migrate: Fix ref-count handling when !hugepage_migration_supported() Date: Thu, 25 May 2017 14:51:46 +0100 Message-Id: <20170525135146.32011-1-punit.agrawal@arm.com> X-Mailer: git-send-email 2.11.0 X-ARM-No-Footer: FoSSMail Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: [] 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(). Reported-by: Manoj Iyer Suggested-by: Naoya Horiguchi Signed-off-by: Punit Agrawal Cc: Joonsoo Kim Cc: Wanpeng Li Cc: Christoph Lameter Cc: # v3.14+ -- Changes since v1: * Added stable tag * Updated patch to use putback_movable_pages() in soft_offline_huge_page() in place of dropping putback_active_hugepage() when hugepage migration is not enabled. This patch was tested on v4.12-rc2 with the series to enable memory corruption handling[0]. [0] https://www.spinics.net/lists/arm-kernel/msg581657.html --- mm/memory-failure.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 44a6a33af219..89f9924777fa 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1603,7 +1603,8 @@ static int soft_offline_huge_page(struct page *page, int flags) * 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 { -- 2.11.0