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 E8D2BC433F5 for ; Mon, 7 Mar 2022 05:01:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235233AbiCGFCd (ORCPT ); Mon, 7 Mar 2022 00:02:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbiCGFCb (ORCPT ); Mon, 7 Mar 2022 00:02:31 -0500 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0B941D0F8 for ; Sun, 6 Mar 2022 21:01:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1646629297; x=1678165297; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=NFKgQZkdrQx8p8nN/Isk9HvHRlX5csN9smzrhWRrW1E=; b=PBUg1Lf5POqM4nOjWwTeXqfKB+tb9PNqCzOrDFFY42YhBdBYcmOrFdYP Ne4qtkjwWUYq8oc5L++Kf6l37KH66aEcASzgbsbCa7xesDfhFBoEfwqYR FmBmkI0vzSRL68lvNFofkRGSOzk6DagO19VcruJQJP/zTrNGPGs/F/xjD ZphBGm8cK/bacmOq6fkiRoQqCIjy4VEhaJasxQfme8u2eryzciixG2Nv0 bO72ctSMXx3FhH79ho8ZO+aI0961TW/yneQ1jTotW2cI8tWQTMhSbSVJ3 QWg+mXA31qys/MOY32lIqkwafTF/lkWnAOhjnzKueDXbf6LRvICTpat2s A==; X-IronPort-AV: E=McAfee;i="6200,9189,10278"; a="234253576" X-IronPort-AV: E=Sophos;i="5.90,160,1643702400"; d="scan'208";a="234253576" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2022 21:01:37 -0800 X-IronPort-AV: E=Sophos;i="5.90,160,1643702400"; d="scan'208";a="552994919" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.239.13.94]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2022 21:01:32 -0800 From: "Huang, Ying" To: Miaohe Lin Cc: , , , , , , , , , , , , , , , , , 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> Date: Mon, 07 Mar 2022 13:01:30 +0800 In-Reply-To: <20220304093409.25829-13-linmiaohe@huawei.com> (Miaohe Lin's message of "Fri, 4 Mar 2022 17:34:05 +0800") Message-ID: <87r17e5pat.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 Miaohe Lin writes: > 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; It appears that we don't need to change nr_failed, because we don't use it for this situation. Otherwise looks good to me. Reviewed-by: "Huang, Ying" Best Regards, Huang, Ying > + nr_thp_failed += thp_retry; > goto out; > case -EAGAIN: > if (is_thp)