From patchwork Wed May 24 15:47:28 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Punit Agrawal X-Patchwork-Id: 9746291 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D992D60209 for ; Wed, 24 May 2017 15:48:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C9297289B2 for ; Wed, 24 May 2017 15:48:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BD624289B4; Wed, 24 May 2017 15:48:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5DAEF289B5 for ; Wed, 24 May 2017 15:48:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=Apyfs//BgWcrMlQzISHC+sDMbZ/zoJcg5YCoTG9O6zk=; b=NX0 E84HZQf24yOWEUTO6lh/Uy8C5F37i7sb+Gy0USnCKgNHmOxK4T3PkZKs8Y2K7cdLMzZsSb33DLpzR dtf94lcQJdjRrNQx7tG9qME4/4CtmalwMv1G1mAWjdZLuuUeODE1oFZInj2g/yaRAJo4NRiSVwoPa ZDw8KT9ej0dfatoLhEfpvqYqpJwNYB1PmOLY8TyupmnvNcqa9+wWMmniEEiDtwer1HXwiiPskBrEd Q8qzKEQKjEL2D3UydF1XyzuZdWovkeoC2XLdBw4uWkXhDgRrvQfhNebC6MykHDVWajpBu1RfaOXDg /ORJpxqJinPvOycc3SYHEWiLIdzLfww==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dDYWD-0001uZ-Mu; Wed, 24 May 2017 15:48:13 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dDYW8-0001hs-VY for linux-arm-kernel@lists.infradead.org; Wed, 24 May 2017 15:48:11 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AFC9A2B; Wed, 24 May 2017 08:47:48 -0700 (PDT) Received: from localhost (e105922-lin.cambridge.arm.com [10.1.207.56]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7DC553F53D; Wed, 24 May 2017 08:47:48 -0700 (PDT) From: Punit Agrawal To: Andrew Morton Subject: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported() Date: Wed, 24 May 2017 16:47:28 +0100 Message-Id: <20170524154728.2492-1-punit.agrawal@arm.com> X-Mailer: git-send-email 2.11.0 X-ARM-No-Footer: FoSSMail X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170524_084809_168703_4EBA14EA X-CRM114-Status: GOOD ( 10.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Christoph Lameter , tbaicar@codeaurora.org, Naoya Horiguchi , catalin.marinas@arm.com, Wanpeng Li , Punit Agrawal , will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, manoj.iyer@arm.com, Joonsoo Kim , timur@qti.qualcomm.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 Tested-By: Manoj Iyer --- 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); + if (!hugepage_migration_supported(page_hstate(hpage))) return -ENOSYS; - } new_hpage = get_new_page(hpage, private, &result); if (!new_hpage)