From patchwork Tue Dec 19 13:28:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michal Hocko X-Patchwork-Id: 10123239 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 E9F89603B5 for ; Tue, 19 Dec 2017 13:29:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DEA4A286B3 for ; Tue, 19 Dec 2017 13:29:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D37BB2872A; Tue, 19 Dec 2017 13:29:07 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 00FF8286B3 for ; Tue, 19 Dec 2017 13:29:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964892AbdLSN3E (ORCPT ); Tue, 19 Dec 2017 08:29:04 -0500 Received: from mail-pl0-f67.google.com ([209.85.160.67]:42964 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936971AbdLSN26 (ORCPT ); Tue, 19 Dec 2017 08:28:58 -0500 Received: by mail-pl0-f67.google.com with SMTP id bd8so6949171plb.9; Tue, 19 Dec 2017 05:28:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=mun3fMio5dm3tUf7j+BklB0nWRPR116XwHgo+zFDu3E=; b=Xl/6hlAO0BI6JcTjuI0kFBAhu+3e9jrBeHfg5fzsL/SXjslwknbQqE9NeAGpsaL6LK 2Oxm6AH0WsHpS3PJ07jqrkAYJJn9jLbC5lD9ocE5Q3H1l1xNFbmkExJ5haZm2ONkqqgJ KR1nUsLTqC42m/XuP9cvcDtNTkg087InOsrbpFUhGVfCreqjHmPRtY9GUhMMcVyYj/KK RXwlVCErGLI1xlQIei2SlIgDfoyYMz0/8nArLqPWE4+nb/4/AdlgCNG1HS6yezkcWqn8 q5nx4nzWlBrrlehYOSReEZdabyOvl4nLTCckLmcYEQG0VapzuH9gK6t1ijbW+wQ9BCHI DZAQ== X-Gm-Message-State: AKGB3mKyogWRcrYcyuXHuTrYJ/vNk1eG+FXDk/h1NvHwzGY4M0jVnNOp dOxyklKPCaIxjYCVarHPEw4= X-Google-Smtp-Source: ACJfBouhslHXXVqulM5lQlEhhM0wIlKXIiGudWcMGs4nzjDHd4hNvStBP7qV7/+bRmPH4lVk9cn/eA== X-Received: by 10.84.133.108 with SMTP id 99mr3352627plf.48.1513690137441; Tue, 19 Dec 2017 05:28:57 -0800 (PST) Received: from tiehlicka.suse.cz (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id f79sm32079760pfd.45.2017.12.19.05.28.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Dec 2017 05:28:56 -0800 (PST) From: Michal Hocko To: Andrew Morton Cc: Al Viro , Tetsuo Handa , Aliaksei Karaliou , , , LKML , Glauber Costa , Michal Hocko Subject: [PATCH 1/2] mm, vmscan: Make unregister_shrinker() no-op if register_shrinker() failed. Date: Tue, 19 Dec 2017 14:28:43 +0100 Message-Id: <20171219132844.28354-2-mhocko@kernel.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171219132844.28354-1-mhocko@kernel.org> References: <20171219132844.28354-1-mhocko@kernel.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Tetsuo Handa Since allowing register_shrinker() callers to call unregister_shrinker() when register_shrinker() failed can simplify error recovery path, this patch makes unregister_shrinker() no-op when register_shrinker() failed. Let's also make sure that double unregister_shrinker doesn't blow up as well and NULL nr_deferred on successful de-registration to make the clean up even simpler and prevent from potential memory corruptions. [akaraliou.dev@gmail.com: set nr_deferred = NULL to handle double unregister] Signed-off-by: Tetsuo Handa Reported-by: syzbot Cc: Glauber Costa Cc: Al Viro Signed-off-by: Michal Hocko --- mm/vmscan.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index 80dea50f421b..7a5801040fd4 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -281,10 +281,13 @@ EXPORT_SYMBOL(register_shrinker); */ void unregister_shrinker(struct shrinker *shrinker) { + if (!shrinker->nr_deferred) + return; down_write(&shrinker_rwsem); list_del(&shrinker->list); up_write(&shrinker_rwsem); kfree(shrinker->nr_deferred); + shrinker->nr_deferred = NULL; } EXPORT_SYMBOL(unregister_shrinker);