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=ham 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 54F2AC43603 for ; Mon, 16 Dec 2019 18:03:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AA77207FF for ; Mon, 16 Dec 2019 18:03:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519427; bh=I1pM00sAx1NXWrBCRm+Y2c8vbUDiPb+MHsbOUbAf5Rk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NlllnPOHlcOBikqaz+qfN0lfMnIJ5yzzbCTUUBCLFs70nLVjE92BNDwXAT93ulI50 Q7h8GAbA6X62xUOyYno1ZKMKDd23BNRDBVZqk9h2kXD33MfPGH+uw/Kg3o9P3lGKGZ 74o3zk+G4wOZUCRDowyu+eUBboGxk2sfu3t+hGKc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729553AbfLPSDq (ORCPT ); Mon, 16 Dec 2019 13:03:46 -0500 Received: from mail.kernel.org ([198.145.29.99]:40642 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729541AbfLPSDm (ORCPT ); Mon, 16 Dec 2019 13:03:42 -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 09B2620726; Mon, 16 Dec 2019 18:03:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519421; bh=I1pM00sAx1NXWrBCRm+Y2c8vbUDiPb+MHsbOUbAf5Rk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ad4xR9Pidmdih2o77bMF8+X7EFxMpH31wvlSMBpcF7+QwRmYCJdyYHRdX2hV7qQSU CHF/XJMk9pPtfQq/BHtekyn0zDeRoWuRVEsK3zZMtNPZMJpteOoCi7vGW8BtltmxQP j7xgAR7E5OT59bqVhzFEfcLUKQoOtG0UdmABo3Rg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Aleksa Sarai , Tejun Heo Subject: [PATCH 4.19 060/140] cgroup: pids: use atomic64_t for pids->limit Date: Mon, 16 Dec 2019 18:48:48 +0100 Message-Id: <20191216174804.341263986@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191216174747.111154704@linuxfoundation.org> References: <20191216174747.111154704@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: 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; /* Handle for "pids.events" */ struct cgroup_file events_file; @@ -76,8 +76,8 @@ 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); atomic64_set(&pids->events_limit, 0); return &pids->css; } @@ -149,13 +149,14 @@ 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; } @@ -280,7 +281,7 @@ 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; } @@ -288,7 +289,7 @@ 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);