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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F546C3A5A3 for ; Tue, 27 Aug 2019 08:12:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 416DD2173E for ; Tue, 27 Aug 2019 08:12:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566893574; bh=98BKHUssZiAvVoIeeamna4LlHN+bPH8+OD69xuUHJas=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WJ7XCSBJOm78X0W3/fOGi45n2EyJEY9sL6io2gXARUlWIBoH7XXV292LSX62kDnB/ kLNof2fBCGWbU1cP1JVko/vyHk4dFkNQfD7X2bFBAECnEaFo0DGQb0OTcUVFUoPJSZ 6ghc7lqe3ppTmxBYc+ZcSPIQd+urK1MUNhsz+En0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729543AbfH0H6q (ORCPT ); Tue, 27 Aug 2019 03:58:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:51398 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731023AbfH0H6d (ORCPT ); Tue, 27 Aug 2019 03:58:33 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A792E2173E; Tue, 27 Aug 2019 07:58:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566892712; bh=98BKHUssZiAvVoIeeamna4LlHN+bPH8+OD69xuUHJas=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w1oVHI82rCSpKLMXob0mrYDvndfJ3nxPjQ1aUe1IBdCIah0ELlxiPaONf4ynU+y6Z KQGQNXhUNfNlviamAbVZYJ5XULPSNzWljuOYgiFS8egNn528rSJPCMyPBzJ1gIIwlf IFmkdHtlvVB9VGJogabpsK5p+4VVd3/SWRKrMc7g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Henry Burns , Sergey Senozhatsky , Henry Burns , Minchan Kim , Shakeel Butt , Jonathan Adams , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 86/98] mm/zsmalloc.c: migration can leave pages in ZS_EMPTY indefinitely Date: Tue, 27 Aug 2019 09:51:05 +0200 Message-Id: <20190827072722.502224783@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190827072718.142728620@linuxfoundation.org> References: <20190827072718.142728620@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Henry Burns commit 1a87aa03597efa9641e92875b883c94c7f872ccb upstream. In zs_page_migrate() we call putback_zspage() after we have finished migrating all pages in this zspage. However, the return value is ignored. If a zs_free() races in between zs_page_isolate() and zs_page_migrate(), freeing the last object in the zspage, putback_zspage() will leave the page in ZS_EMPTY for potentially an unbounded amount of time. To fix this, we need to do the same thing as zs_page_putback() does: schedule free_work to occur. To avoid duplicated code, move the sequence to a new putback_zspage_deferred() function which both zs_page_migrate() and zs_page_putback() call. Link: http://lkml.kernel.org/r/20190809181751.219326-1-henryburns@google.com Fixes: 48b4800a1c6a ("zsmalloc: page migration support") Signed-off-by: Henry Burns Reviewed-by: Sergey Senozhatsky Cc: Henry Burns Cc: Minchan Kim Cc: Shakeel Butt Cc: Jonathan Adams Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/zsmalloc.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1882,6 +1882,18 @@ static void dec_zspage_isolation(struct zspage->isolated--; } +static void putback_zspage_deferred(struct zs_pool *pool, + struct size_class *class, + struct zspage *zspage) +{ + enum fullness_group fg; + + fg = putback_zspage(class, zspage); + if (fg == ZS_EMPTY) + schedule_work(&pool->free_work); + +} + static void replace_sub_page(struct size_class *class, struct zspage *zspage, struct page *newpage, struct page *oldpage) { @@ -2051,7 +2063,7 @@ static int zs_page_migrate(struct addres * the list if @page is final isolated subpage in the zspage. */ if (!is_zspage_isolated(zspage)) - putback_zspage(class, zspage); + putback_zspage_deferred(pool, class, zspage); reset_page(page); put_page(page); @@ -2097,14 +2109,13 @@ static void zs_page_putback(struct page spin_lock(&class->lock); dec_zspage_isolation(zspage); if (!is_zspage_isolated(zspage)) { - fg = putback_zspage(class, zspage); /* * Due to page_lock, we cannot free zspage immediately * so let's defer. */ - if (fg == ZS_EMPTY) - schedule_work(&pool->free_work); + putback_zspage_deferred(pool, class, zspage); } + spin_unlock(&class->lock); }