From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DFC7DC433EF for ; Mon, 7 Mar 2022 05:02:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235245AbiCGFDq (ORCPT ); Mon, 7 Mar 2022 00:03:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235246AbiCGFDo (ORCPT ); Mon, 7 Mar 2022 00:03:44 -0500 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BB405F82 for ; Sun, 6 Mar 2022 21:02:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646629369; x=1678165369; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=fSzZifNYct0Has80OHs9poHqh4YGD9Xak8s4xLdqB7U=; b=XVWncK0WA8LJy4CGclOg8eGM8bGoskNxinkaOvAXPbho1MCmHlXSMPoU dj8++DaRN4++DPKzxrUqTdrgRljzrLCBxch2wUtlSGuFFzF009k+LNVTk EjQXE7X20MOuu1y1anbrCSm0UykxMWfkYUR1ha28RfAyPhuXUrfivh1SB unWP7SQnbZdAXAmn6+v4fbWTPlTjsFXKxISX31bBQMYjGv0jWb6axNhKG 4nVZbt3/CYlL6jsdoCgn+53Wo7+cm7puU2P5BwoDG1zppj9jEulkJzaji txEi0w+EHpOorEfTWj0hJhJOFP63SpQ5IXyas/AUo6t4v26DFIaCTDtSi w==; X-IronPort-AV: E=McAfee;i="6200,9189,10278"; a="254028485" X-IronPort-AV: E=Sophos;i="5.90,160,1643702400"; d="scan'208";a="254028485" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2022 21:02:38 -0800 X-IronPort-AV: E=Sophos;i="5.90,160,1643702400"; d="scan'208";a="512535412" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.13.94]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2022 21:02:33 -0800 From: "Huang, Ying" To: Baolin Wang Cc: Miaohe Lin , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH 12/16] mm/migration: fix potential page refcounts leak in migrate_pages References: <20220304093409.25829-1-linmiaohe@huawei.com> <20220304093409.25829-13-linmiaohe@huawei.com> <20f47ec9-3b5b-5326-b1c3-4b1a0c38ef46@linux.alibaba.com> Date: Mon, 07 Mar 2022 13:02:27 +0800 In-Reply-To: <20f47ec9-3b5b-5326-b1c3-4b1a0c38ef46@linux.alibaba.com> (Baolin Wang's message of "Mon, 7 Mar 2022 09:57:30 +0800") Message-ID: <87mti25p98.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Baolin Wang writes: > Hi Miaohe, > > On 3/4/2022 5:34 PM, Miaohe Lin wrote: >> In -ENOMEM case, there might be some subpages of fail-to-migrate THPs >> left in thp_split_pages list. We should move them back to migration >> list so that they could be put back to the right list by the caller >> otherwise the page refcnt will be leaked here. Also adjust nr_failed >> and nr_thp_failed accordingly to make vm events account more accurate. >> Fixes: b5bade978e9b ("mm: migrate: fix the return value of >> migrate_pages()") >> Signed-off-by: Miaohe Lin >> --- >> mm/migrate.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> diff --git a/mm/migrate.c b/mm/migrate.c >> index e0db06927f02..6c2dfed2ddb8 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1422,6 +1422,15 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, >> } >> nr_failed_pages += nr_subpages; >> + /* >> + * There might be some subpages of fail-to-migrate THPs >> + * left in thp_split_pages list. Move them back to migration >> + * list so that they could be put back to the right list by >> + * the caller otherwise the page refcnt will be leaked. >> + */ >> + list_splice_init(&thp_split_pages, from); >> + nr_failed += retry; >> + nr_thp_failed += thp_retry; > > Yes, I think we missed this case before, and your patch looks > right. But we should also update the 'rc' to return the correct number > of pages that were not migrated, right? Per my understanding, -ENOMEM should be returned to indicate an fatal error. Best Regards, Huang, Ying