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=-12.8 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1, USER_IN_DEF_DKIM_WL 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 81B24CA9EAF for ; Thu, 24 Oct 2019 19:01:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51B742070B for ; Thu, 24 Oct 2019 19:01:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="C98ZSUR/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504224AbfJXTBl (ORCPT ); Thu, 24 Oct 2019 15:01:41 -0400 Received: from mail-pl1-f193.google.com ([209.85.214.193]:40143 "EHLO mail-pl1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390493AbfJXTBk (ORCPT ); Thu, 24 Oct 2019 15:01:40 -0400 Received: by mail-pl1-f193.google.com with SMTP id d22so12312120pll.7 for ; Thu, 24 Oct 2019 12:01:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:in-reply-to:message-id:references :user-agent:mime-version; bh=lGCdcxYn0fhxI/F+Acv75O+uiNWd2Mq3qhp7qlP+npM=; b=C98ZSUR/4d7JgbXxedGADnm9ri1iP+4j59mYVyshMzIB+sPNTq05Zx/Wvh2qYBb58q 1F+xh7GoGea48bavabDj0ISu0sjYZC2Ueu8LRYU3BQ0EuXp1Zpj0MTybaPsAxY6GG6NQ Rt+ON+PG2M2hpYS+huhURc4FwH8K5579hZhS1gKlJAhfIRoLZUwoxFDC3QpM+RCWWAUL jrMDguCosKTJyInDGKkATia4svm81xLkg79QnHUUAEyUxHNLoCyEjliw6+QTloDbmEwJ GqyzRY6gUVfwF4Vf9si1UNdIc8179Q+i1bFZwYIFnMJ1d9/h5yG2EToWNYkRZ1KZU0D5 uAFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version; bh=lGCdcxYn0fhxI/F+Acv75O+uiNWd2Mq3qhp7qlP+npM=; b=ngOXMkJaXToWVGBgLyr1+6TLlXx4wCXQ10CakTXnnLqSOpYyUTyLUbjJINPdcGGDZV JcFB1yM0FSvzrLdX+NNcZIxDa6dZqOBeboBp9OTnB/cfORONHIcyzFMTJi1n0jjWvMek hAZ2MkYkj2cdLDHsviYCDzTyP1nEIVeJbPp/JVZi+lviA6/faXGT06IhX0UOiKtsFeZi VBaEJ9MdL92u31pZQupbRI4VuPRMWVjZxSu30SockPpnKBFuv2N8KM7KyYgqk8DhkkJW 5qKYG0ZKAc3rmY1yafgNTUoStAzYTzGojEtwBhDAssrOGnRDkx/qfhERbC+7wQKB9UDm eyxw== X-Gm-Message-State: APjAAAWl0NFKvsjMJTSuYMv1tvi1Q/btpg3AFpPGzozn4qmjIA4fWdG5 FJqe12AErn008cRA9T0noLgPXQ== X-Google-Smtp-Source: APXvYqzMMHkwWVYf0svd1U4v301GL37PukLhZ41swJwynvJ3Hp2SER4PxVa6VktAX8Ez3A4qBWK+uA== X-Received: by 2002:a17:902:d698:: with SMTP id v24mr17062393ply.340.1571943699729; Thu, 24 Oct 2019 12:01:39 -0700 (PDT) Received: from [2620:15c:17:3:3a5:23a7:5e32:4598] ([2620:15c:17:3:3a5:23a7:5e32:4598]) by smtp.gmail.com with ESMTPSA id j12sm3453005pjz.12.2019.10.24.12.01.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Oct 2019 12:01:38 -0700 (PDT) Date: Thu, 24 Oct 2019 12:01:38 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Michal Hocko cc: Andrew Morton , Mel Gorman , Waiman Long , Johannes Weiner , Roman Gushchin , Vlastimil Babka , Konstantin Khlebnikov , Jann Horn , Song Liu , Greg Kroah-Hartman , Rafael Aquini , linux-mm@kvack.org, LKML , Michal Hocko Subject: Re: [RFC PATCH 1/2] mm, vmstat: hide /proc/pagetypeinfo from normal users In-Reply-To: <20191023102737.32274-2-mhocko@kernel.org> Message-ID: References: <20191023095607.GE3016@techsingularity.net> <20191023102737.32274-1-mhocko@kernel.org> <20191023102737.32274-2-mhocko@kernel.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 23 Oct 2019, Michal Hocko wrote: > From: Michal Hocko > > /proc/pagetypeinfo is a debugging tool to examine internal page > allocator state wrt to fragmentation. It is not very useful for > any other use so normal users really do not need to read this file. > > Waiman Long has noticed that reading this file can have negative side > effects because zone->lock is necessary for gathering data and that > a) interferes with the page allocator and its users and b) can lead to > hard lockups on large machines which have very long free_list. > > Reduce both issues by simply not exporting the file to regular users. > > Reported-by: Waiman Long > Cc: stable > Signed-off-by: Michal Hocko Acked-by: David Rientjes