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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 7AD6AC433E6 for ; Tue, 1 Sep 2020 17:16:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6581920866 for ; Tue, 1 Sep 2020 17:16:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732575AbgIARQj (ORCPT ); Tue, 1 Sep 2020 13:16:39 -0400 Received: from verein.lst.de ([213.95.11.211]:53770 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728585AbgIAPOX (ORCPT ); Tue, 1 Sep 2020 11:14:23 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 0183E68B05; Tue, 1 Sep 2020 17:14:21 +0200 (CEST) Date: Tue, 1 Sep 2020 17:14:20 +0200 From: Christoph Hellwig To: Josef Bacik Cc: hch@lst.de, viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, kernel-team@fb.com Subject: Re: [PATCH 1/6] proc: use vmalloc for our kernel buffer Message-ID: <20200901151420.GA30709@lst.de> References: <20200813210411.905010-1-josef@toxicpanda.com> <20200813210411.905010-2-josef@toxicpanda.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200813210411.905010-2-josef@toxicpanda.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Aug 13, 2020 at 05:04:06PM -0400, Josef Bacik wrote: > Since > > sysctl: pass kernel pointers to ->proc_handler > > we have been pre-allocating a buffer to copy the data from the proc > handlers into, and then copying that to userspace. The problem is this > just blind kmalloc()'s the buffer size passed in from the read, which in > the case of our 'cat' binary was 64kib. Order-4 allocations are not > awesome, and since we can potentially allocate up to our maximum order, > use vmalloc for these buffers. Maybe the subject should read ".. also use vmalloc" as we still default to kmalloc for small allocations? Otherwise looks good: Reviewed-by: Christoph Hellwig