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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 A4088C433E0 for ; Tue, 7 Jul 2020 15:23:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 806192065D for ; Tue, 7 Jul 2020 15:23:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594135391; bh=gd92U56RmoV99eATKd4qvxZYYmO56fFyB+M5e7f5O3c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=n794+nkPyxzXy9m0VbA6M4UBzWa5S8PAXZx3GXuc0T5CNp+deGc+2NAZy9i1ti7qA vd9qFBjsrf+U1n/ihrZj/Ewr1YNNQ1MYzRzDPAyJ08iiGc2J3ezv1B7NvtoVOQeCtN jv3xZ4ll2sLDbNCOFugIoMbDUGzAxLSEAZXRecFY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729949AbgGGPXJ (ORCPT ); Tue, 7 Jul 2020 11:23:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:36060 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729941AbgGGPXH (ORCPT ); Tue, 7 Jul 2020 11:23:07 -0400 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 435A5206F6; Tue, 7 Jul 2020 15:23:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594135386; bh=gd92U56RmoV99eATKd4qvxZYYmO56fFyB+M5e7f5O3c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q3YBIg9VLYuXYEmaeU3uozl2TJozPSU8j9kqwfiHj/CU8OqiwkWIeckETrsn5rj5X 6GHvYgsHeoWPhZ8M+OAh+Gft9FmGUrqVZbvxmHf5q279BR+Hyuof7VKhObAWNa5/1C 0Wo7uhJ4PFZ+tcROSB+6g7irxFdJSZNkRVP6DCu0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Valentin Schneider , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.7 020/112] sched/debug: Make sd->flags sysctl read-only Date: Tue, 7 Jul 2020 17:16:25 +0200 Message-Id: <20200707145801.948953381@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200707145800.925304888@linuxfoundation.org> References: <20200707145800.925304888@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: Valentin Schneider [ Upstream commit 9818427c6270a9ce8c52c8621026fe9cebae0f92 ] Writing to the sysctl of a sched_domain->flags directly updates the value of the field, and goes nowhere near update_top_cache_domain(). This means that the cached domain pointers can end up containing stale data (e.g. the domain pointed to doesn't have the relevant flag set anymore). Explicit domain walks that check for flags will be affected by the write, but this won't be in sync with the cached pointers which will still point to the domains that were cached at the last sched_domain build. In other words, writing to this interface is playing a dangerous game. It could be made to trigger an update of the cached sched_domain pointers when written to, but this does not seem to be worth the trouble. Make it read-only. Signed-off-by: Valentin Schneider Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200415210512.805-3-valentin.schneider@arm.com Signed-off-by: Sasha Levin --- kernel/sched/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 239970b991c03..0f4aaad236a9d 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -258,7 +258,7 @@ sd_alloc_ctl_domain_table(struct sched_domain *sd) set_table_entry(&table[2], "busy_factor", &sd->busy_factor, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[3], "imbalance_pct", &sd->imbalance_pct, sizeof(int), 0644, proc_dointvec_minmax); set_table_entry(&table[4], "cache_nice_tries", &sd->cache_nice_tries, sizeof(int), 0644, proc_dointvec_minmax); - set_table_entry(&table[5], "flags", &sd->flags, sizeof(int), 0644, proc_dointvec_minmax); + set_table_entry(&table[5], "flags", &sd->flags, sizeof(int), 0444, proc_dointvec_minmax); set_table_entry(&table[6], "max_newidle_lb_cost", &sd->max_newidle_lb_cost, sizeof(long), 0644, proc_doulongvec_minmax); set_table_entry(&table[7], "name", sd->name, CORENAME_MAX_SIZE, 0444, proc_dostring); /* &table[8] is terminator */ -- 2.25.1