From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 448866B0292 for ; Thu, 25 May 2017 06:18:11 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id c10so224109085pfg.10 for ; Thu, 25 May 2017 03:18:11 -0700 (PDT) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id u143si26457124pgb.67.2017.05.25.03.18.09 for ; Thu, 25 May 2017 03:18:10 -0700 (PDT) From: Punit Agrawal Subject: Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported() References: <20170524154728.2492-1-punit.agrawal@arm.com> <20170525015927.GA26520@hori1.linux.bs1.fc.nec.co.jp> Date: Thu, 25 May 2017 11:18:06 +0100 In-Reply-To: <20170525015927.GA26520@hori1.linux.bs1.fc.nec.co.jp> (Naoya Horiguchi's message of "Thu, 25 May 2017 01:59:28 +0000") Message-ID: <87tw49dyu9.fsf@e105922-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Naoya Horiguchi Cc: Andrew Morton , "will.deacon@arm.com" , "catalin.marinas@arm.com" , "manoj.iyer@arm.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mm@kvack.org" , "tbaicar@codeaurora.org" , "timur@qti.qualcomm.com" , Joonsoo Kim , Wanpeng Li , Christoph Lameter Naoya Horiguchi writes: > On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote: >> 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 >> >> Fix this by dropping the ref-count decrement in >> unmap_and_move_hugepage() when !hugepage_migration_supported(). >> >> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()") >> Reported-by: Manoj Iyer >> Signed-off-by: Punit Agrawal >> Cc: Joonsoo Kim >> Cc: Naoya Horiguchi >> Cc: Wanpeng Li >> Cc: Christoph Lameter >> >> -- >> Hi Andrew, >> >> We ran into this bug when working towards enabling memory corruption >> on arm64. The patch was tested on an arm64 platform running v4.12-rc2 >> with the series to enable memory corruption handling[0]. >> >> Please consider merging as a fix for the 4.12 release. >> >> Thanks, >> Punit >> >> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html >> --- >> mm/migrate.c | 4 +--- >> 1 file changed, 1 insertion(+), 3 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 89a0a1707f4c..187abd1526df 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, >> * tables or check whether the hugepage is pmd-based or not before >> * kicking migration. >> */ >> - if (!hugepage_migration_supported(page_hstate(hpage))) { >> - putback_active_hugepage(hpage); > > Thank you for reporting and suggestion, Punit, Manoj. > > Simply dropping this putback_active_hugepage() may resume the failure > counting issue addressed in 32665f2bbfed, so I would recommend to call > putback_movable_pages() in failure path in soft_offline_huge_page(). > > @@ -1600,7 +1600,8 @@ 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 { > > Could you check this works for you? Using this sequence works as well. I'll send out an update shortly. Thanks > > Thanks, > Naoya Horiguchi > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org