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,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 1766AC2D0C1 for ; Thu, 19 Dec 2019 19:10:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D91B724672 for ; Thu, 19 Dec 2019 19:10:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576782626; bh=UJD928C7anYrORACAu6Oao0G9JR8oRn8ffJSvKjKt3I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Vtk+qm/DVpSeBCZbQJIVM2+6N4qJ1v8i5w9xCbc20P5jcDS+BxIHKiM4xJQEEMD8w ZSsHKPT7ucPkR2w2+5Y0DR7jQ7o6tj65tYO848V2RxkCn98L2ZKzoBIxdCcN3uHxRs sUcvQqzr8dG0/XAUrpRYC2MKfBiWtEyLB3NnHXkE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728241AbfLSSje (ORCPT ); Thu, 19 Dec 2019 13:39:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:57868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728235AbfLSSje (ORCPT ); Thu, 19 Dec 2019 13:39:34 -0500 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 E402220716; Thu, 19 Dec 2019 18:39:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576780773; bh=UJD928C7anYrORACAu6Oao0G9JR8oRn8ffJSvKjKt3I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HJBuLZMBeK4bejroaSDA+2OOm7nrfrISG27JG6x4OStMzi0QkDoKcmJO986gN6iqp K47+h4C95KRrCze9l/qTCtz3AQseOD64uWKAqih3rflUYIbUPGxl8rVIYE5L3DNFyC EpjS0Z6XOi/dC/Ib0His69tF16YPiXPgf4gvKg+s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aleksa Sarai , Tejun Heo Subject: [PATCH 4.4 109/162] cgroup: pids: use atomic64_t for pids->limit Date: Thu, 19 Dec 2019 19:33:37 +0100 Message-Id: <20191219183214.393367665@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191219183150.477687052@linuxfoundation.org> References: <20191219183150.477687052@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Aleksa Sarai commit a713af394cf382a30dd28a1015cbe572f1b9ca75 upstream. Because pids->limit can be changed concurrently (but we don't want to take a lock because it would be needlessly expensive), use atomic64_ts instead. Fixes: commit 49b786ea146f ("cgroup: implement the PIDs subsystem") Cc: stable@vger.kernel.org # v4.3+ Signed-off-by: Aleksa Sarai Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup_pids.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/kernel/cgroup_pids.c +++ b/kernel/cgroup_pids.c @@ -48,7 +48,7 @@ struct pids_cgroup { * %PIDS_MAX = (%PID_MAX_LIMIT + 1). */ atomic64_t counter; - int64_t limit; + atomic64_t limit; }; static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css) @@ -70,8 +70,8 @@ pids_css_alloc(struct cgroup_subsys_stat if (!pids) return ERR_PTR(-ENOMEM); - pids->limit = PIDS_MAX; atomic64_set(&pids->counter, 0); + atomic64_set(&pids->limit, PIDS_MAX); return &pids->css; } @@ -142,13 +142,14 @@ static int pids_try_charge(struct pids_c for (p = pids; parent_pids(p); p = parent_pids(p)) { int64_t new = atomic64_add_return(num, &p->counter); + int64_t limit = atomic64_read(&p->limit); /* * Since new is capped to the maximum number of pid_t, if * p->limit is %PIDS_MAX then we know that this test will never * fail. */ - if (new > p->limit) + if (new > limit) goto revert; } @@ -262,7 +263,7 @@ set_limit: * Limit updates don't need to be mutex'd, since it isn't * critical that any racing fork()s follow the new limit. */ - pids->limit = limit; + atomic64_set(&pids->limit, limit); return nbytes; } @@ -270,7 +271,7 @@ static int pids_max_show(struct seq_file { struct cgroup_subsys_state *css = seq_css(sf); struct pids_cgroup *pids = css_pids(css); - int64_t limit = pids->limit; + int64_t limit = atomic64_read(&pids->limit); if (limit >= PIDS_MAX) seq_printf(sf, "%s\n", PIDS_MAX_STR);