From patchwork Fri Aug 19 17:19:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: SeongJae Park X-Patchwork-Id: 12948986 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEAC5C28B2B for ; Fri, 19 Aug 2022 17:19:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 429398D0003; Fri, 19 Aug 2022 13:19:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D9188D0002; Fri, 19 Aug 2022 13:19:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2C81D8D0003; Fri, 19 Aug 2022 13:19:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 195A28D0002 for ; Fri, 19 Aug 2022 13:19:39 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id E1D121219D6 for ; Fri, 19 Aug 2022 17:19:38 +0000 (UTC) X-FDA: 79817004036.15.D62CE35 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf29.hostedemail.com (Postfix) with ESMTP id 9C27112016F for ; Fri, 19 Aug 2022 17:19:37 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id ACB506170E; Fri, 19 Aug 2022 17:19:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85184C433C1; Fri, 19 Aug 2022 17:19:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660929576; bh=3Sdln9qJKHLzw3ch7twkCCMwF2dg/LGZE0fJeB2Pqds=; h=From:To:Cc:Subject:Date:From; b=WDXGks4O7BdiqUE7X0ObnfF1Zyc1+QRtTDQWZKrcu/dYHW20fJbBaY5zTopwpzRcr iT1CheRg5d9nG1nbiK+07tKfvbRrMPPAzYs5xdQS9G94QOx6JiQ+CZqnjz5bLfoTQM 8GizFsATxnYxbVf0njAQVdq4u3/+gJxXl8HMgOFRfzNYQuZFqeZm2bQA2iehreJcJr MsgssHY7b9NDzkvL3zvPSqZdzev4Zl7VTNxdSDSPb4x7IYajtOS5mXMkGX9sEwD/g5 YzO+4CjEDdZnIOJknjJdGpijVe7LNFh8j3wLUZmLKeBi2YCJXcIkfdlNSLufGy6I/p rjfnuFJRi3Ofg== From: SeongJae Park To: akpm@linux-foundation.org Cc: sj@kernel.org, badari.pulavarty@intel.com, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v2] mm/damon/dbgfs: avoid duplicate context directory creation Date: Fri, 19 Aug 2022 17:19:30 +0000 Message-Id: <20220819171930.16166-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660929577; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=YRNVGuqBMqSe1T+K1vbiMac58elYeGeNvRwhGk1LiBY=; b=oJxz4VMcs5XRba5ZOIVFBg8mfRQlr9eWduM2lf2KAuulMF7qfWGZm4UNxexA+RmaLkUz8/ Y+tDXWc9jbTSfsvceFVBUnlRzJpsGMCA2yJ1Y/tihjwe5RO2JHLGuiK9Qvld/6Pr5Ev0o/ QaLPp4wKtMQKxHdbHoljamk9o1XtxSw= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WDXGks4O; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660929577; a=rsa-sha256; cv=none; b=aW2keWbjcHpEptFPBSCUSY7HCzhEmfkyL7EavBpBhM0EtzTLjT5vyzbGFlze7Q/eOtbs5o aZhtXW3ICkwOfNM50m4HdQkHi1Gl/ntJvAjM0ktq6pFdUZaxD1VJKiFUjsNTb8PUUNiUPW 9TyylBL+5gcw+uM4+yPvHIICaKaw72A= X-Stat-Signature: 73nzn43ropqrqsux9xoxex5byeng6iw3 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9C27112016F Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=WDXGks4O; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of sj@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=sj@kernel.org X-Rspam-User: X-HE-Tag: 1660929577-657217 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Badari Pulavarty When user tries to create a DAMON context via the DAMON debugfs interface with a name of an already existing context, the context directory creation silently fails but the context is added in the internal data structure. As a result, memory could leak and DAMON cannot be turned on. An example test case is as below: # cd /sys/kernel/debug/damon/ # echo "off" > monitor_on # echo paddr > target_ids # echo "abc" > mk_context # echo "abc" > mk_context # echo $$ > abc/target_ids # echo "on" > monitor_on <<< fails This commit fixes the issue by checking if the name already exist and immediately returning '-EEXIST' in the case. Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts") Cc: # 5.15.x Signed-off-by: Badari Pulavarty Signed-off-by: SeongJae Park --- Changes from v1 (https://lore.kernel.org/damon/DM6PR11MB3978994F75A4104D714437379C679@DM6PR11MB3978.namprd11.prod.outlook.com/) - Manually check duplicate entry instead of checking 'debugfs_create_dir()' return value - Reword commit message and the test case Seems Badari have some email client issue, so I (SJ) am making this second version of the patch based on Badari's final proposal and repost on behalf of Badari. mm/damon/dbgfs.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 51d67c8050dd..364b44063c2f 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -795,7 +795,7 @@ static void dbgfs_destroy_ctx(struct damon_ctx *ctx) */ static int dbgfs_mk_context(char *name) { - struct dentry *root, **new_dirs, *new_dir; + struct dentry *root, **new_dirs, *new_dir, *dir; struct damon_ctx **new_ctxs, *new_ctx; if (damon_nr_running_ctxs()) @@ -817,6 +817,12 @@ static int dbgfs_mk_context(char *name) if (!root) return -ENOENT; + dir = debugfs_lookup(name, root); + if (dir) { + dput(dir); + return -EEXIST; + } + new_dir = debugfs_create_dir(name, root); dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;