Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755281Ab3HWL0E (ORCPT ); Fri, 23 Aug 2013 07:26:04 -0400 Received: from mail-ie0-f179.google.com ([209.85.223.179]:39271 "EHLO mail-ie0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754599Ab3HWL0C (ORCPT ); Fri, 23 Aug 2013 07:26:02 -0400 MIME-Version: 1.0 Date: Fri, 23 Aug 2013 19:26:01 +0800 Message-ID: Subject: [PATCH 0/4] zswap bugfix: memory leaks and other problem From: Weijie Yang To: Minchan Kim , Bob Liu , sjenning@linux.vnet.ibm.com Cc: weijie.yang@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1605 Lines: 35 This patch series fix a few bugs in zswap based on Linux-3.11-rc6. Corresponding mail thread see: lkml.org/lkml/2013/8/18/59 . These issues fixed are: 1. memory leaks when re-swapon 2. potential problem which store and reclaim functions is called recursively 3. memory leaks when invalidate and reclaim occur simultaneously 4. unnecessary page scanning Issues discussed in that mail thread NOT fixed as it happens rarely or not a big problem: 1. a "theoretical race condition" when reclaim page when a handle alloced from zbud, zbud considers this handle is used validly by upper(zswap) and can be a candidate for reclaim. But zswap has to initialize it such as setting swapentry and adding it to rbtree. so there is a race condition, such as: thread 0: obtain handle x from zbud_alloc thread 1: zbud_reclaim_page is called thread 1: callback zswap_writeback_entry to reclaim handle x thread 1: get swpentry from handle x (it is random value now) thread 1: bad thing may happen thread 0: initialize handle x with swapentry 2. frontswap_map bitmap not cleared after zswap reclaim Frontswap uses frontswap_map bitmap to track page in "backend" implementation, when zswap reclaim a page, the corresponding bitmap record is not cleared. mm/zswap.c | 35 ++++++++++++++++++++++++----------- 1 files changed, 24 insertions(+), 11 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/