Received: by 2002:a25:1506:0:0:0:0:0 with SMTP id 6csp4054109ybv; Mon, 10 Feb 2020 11:23:28 -0800 (PST) X-Google-Smtp-Source: APXvYqzyNU+himEsDVFvozz0NTfMvbkaBwEWNpKfahwcn1MOuwh2+ytWufcBvPbJgg5zL39qCaQz X-Received: by 2002:a05:6830:1691:: with SMTP id k17mr2305912otr.282.1581362608866; Mon, 10 Feb 2020 11:23:28 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1581362608; cv=none; d=google.com; s=arc-20160816; b=dN0QAvTylr0uKAVdY2i/3Q+SC+n5PQf9PkQoK6zKuAVOSeV+AVBUZKxvT9CEH0Ylnl RtV6xf92ylyWQURIf6o4wScqTDZdiW28NFZU+DxecpqFJtImTpjKj2803845smpeE85f RvX8k1IGTSCYJk0fAd/M4iv+9Ho/N6CSYCxl+V+2Rr1W/rxn7l1UsOFDccVzQhdtVNY+ j/00icusrzQkEGM4sGKSrJmGe5Cug6HFsnSlAKApuTHHGNE/SvGITQV8MH9BK8vkCDzC 8ZEqM4EbZcq0mBCKShHG7O04Lbt0MLwlS6Ab4aBWuBR5zccfcQY/rys9ruixgECvayWB a63A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:in-reply-to:content-disposition :mime-version:references:message-id:subject:cc:to:from:date; bh=OKgWbnAHULSkL6Z2Q9IStamggKXwVETO5QNwL/yB1c4=; b=HoaN2lwpmaJDQQO6AputhAzdQYWQQrGOEEEAu3BI+NIbLOtLrfXeZ0KywZSbKaSzwA 6Y1OpeVwsd4w67eS3BWvay22pkuc8wVNxF6qyWA3+/k8EIuEgyH97MWSCyeAePwU3aMo 92QpInnd9wPdrWShYtwI98Ph2PQBQc3Blr9muvZTB0yF3+3P8xNVCKzazlziiD7nQIXR HsgzDGgBtft9nG9aTgLPI7cD4UqKdvUCQnjNSMYSuUvVSfXpn873gLtOXFbXiodPteOs MMdc59fJsc7Af6YXG+eLAJ4OrvYuX+HLkUleL1J9PihJuVIKGzaYp/1eVFxfEafTpk3i e/vA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id b10si568884otp.124.2020.02.10.11.23.16; Mon, 10 Feb 2020 11:23:28 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727555AbgBJTXN (ORCPT + 99 others); Mon, 10 Feb 2020 14:23:13 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:35746 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727003AbgBJTXN (ORCPT ); Mon, 10 Feb 2020 14:23:13 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1Ee6-00AWd4-KS; Mon, 10 Feb 2020 19:23:02 +0000 Date: Mon, 10 Feb 2020 19:23:02 +0000 From: Al Viro To: Linus Torvalds Cc: Alexey Gladkov , LKML , Kernel Hardening , Linux API , Linux FS Devel , Linux Security Module , Akinobu Mita , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Daniel Micay , Djalal Harouni , "Dmitry V . Levin" , "Eric W . Biederman" , Greg Kroah-Hartman , Ingo Molnar , "J . Bruce Fields" , Jeff Layton , Jonathan Corbet , Kees Cook , Oleg Nesterov , Solar Designer Subject: Re: [PATCH v8 07/11] proc: flush task dcache entries from all procfs instances Message-ID: <20200210192302.GI23230@ZenIV.linux.org.uk> References: <20200210150519.538333-1-gladkov.alexey@gmail.com> <20200210150519.538333-8-gladkov.alexey@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 10, 2020 at 09:46:26AM -0800, Linus Torvalds wrote: > On Mon, Feb 10, 2020 at 7:06 AM Alexey Gladkov wrote: > > > > This allows to flush dcache entries of a task on multiple procfs mounts > > per pid namespace. > > > > The RCU lock is used because the number of reads at the task exit time > > is much larger than the number of procfs mounts. > > Ok, this looks better to me than the previous version. > > But that may be the "pee-in-the-snow" effect, and I _really_ want > others to take a good look at the whole series. > > The right people seem to be cc'd, but this is pretty core, and /proc > has a tendency to cause interesting issues because of how it's > involved in a lot of areas indirectly. > > Al, Oleg, Andy, Eric? Will check tonight (ears-deep in sorting out the old branches right now)