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=-0.9 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 DB530C5CFFE for ; Tue, 11 Dec 2018 18:41:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5FB420870 for ; Tue, 11 Dec 2018 18:41:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="YDRs11Tk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A5FB420870 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726868AbeLKSl7 (ORCPT ); Tue, 11 Dec 2018 13:41:59 -0500 Received: from mail-io1-f68.google.com ([209.85.166.68]:36359 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726365AbeLKSl6 (ORCPT ); Tue, 11 Dec 2018 13:41:58 -0500 Received: by mail-io1-f68.google.com with SMTP id m19so12678964ioh.3 for ; Tue, 11 Dec 2018 10:41:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:subject:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=aM0+tGaa9kX4JzS0KzV4o9AhtbYFxa2/mQ6p5j8hKME=; b=YDRs11TkjZM3iblmX8W6dUkmMmc8dgaFLRXLgy53AmR8PNo9lSSi65Ba4ijRyu2hbX AayZRhuqzrFGKtv7Yi7dmVi94x7ENHcSKGTi7vt5Cpk47RGyRXOtWglLHaQpxPGOazQm So5y38PVXi6oNdRaK6BazE21Vtj7TBOLMsLjqTpRZUWUY6Bwlhxg0TqjmAzr+q/jtysM /AuXrGf7E+acGpP8qj3KxfTGBFn5MoJhZgrUg4at1zWLCRr9/Gv+VmpVolNzTwp1DADH YBc9g7NPsy7xL7CEaKy3MV0j3vd5I0m6Jp7jbW/mx18uXYm8euPqLDHRca3ValUxNTpI FVtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=aM0+tGaa9kX4JzS0KzV4o9AhtbYFxa2/mQ6p5j8hKME=; b=X5lkMFB0AonxZ17FxJkNtFA+2TjkRo0zsR14fmJovYjU9WG2qMJZRgM394z0UrcjlK rPrBwDNzS74Te/r+KRMUv9X41ctrA0ymXd0NHxZX/C8b5Z5Ij9TSOe51KQ0WK2q9arPr FuDf2xFSlHTq0LSzct+sr1YfBQK3WuN5tDaSVCiW7g3/dZiw7cPoogh+Y8auLfUYLsz0 8jkGWhK96JEmnigyN1Ub4m16Rl6rtr6OLOMbf0uBH05UQZMCE5DLDYwTupMdN2YonPd1 5/1KE2Kpzbb34F1/0f1CU9ehkcwN37H0VLFin5ltSACGcapC3bHsK3KE5icD/yY3Re4+ uriw== X-Gm-Message-State: AA+aEWbaGL293dCv60Jva5aErInkarbwwSJyYVreIfpFSExzfUjVFP7a nfVZ+eOdyYj6m91nr9i6EDZAVg== X-Google-Smtp-Source: AFSGD/UbyPLEK3sR4CdnsOHDBxQYzDVDe3pUQQRwhbqEedkWsvVgP0psS8n2GmjhzibHSZrlZ9lQtw== X-Received: by 2002:a5d:85c5:: with SMTP id e5mr13362205ios.125.1544553717346; Tue, 11 Dec 2018 10:41:57 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id o16sm1619240ito.19.2018.12.11.10.41.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 11 Dec 2018 10:41:56 -0800 (PST) From: Jens Axboe Subject: Re: [PATCH] aio: Convert ioctx_table to XArray To: Matthew Wilcox Cc: Al Viro , Benjamin LaHaise , Andrew Morton , Kees Cook , fsdevel , linux-aio@kvack.org, linux-mm , linux-kernel , Dan Carpenter , Matthew Wilcox References: <20181128183531.5139-1-willy@infradead.org> Message-ID: <09e3d156-66fc-ca17-efac-63f080a27a1d@kernel.dk> Date: Tue, 11 Dec 2018 11:41:55 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181128183531.5139-1-willy@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 28, 2018 at 11:35 AM Matthew Wilcox wrote: > @@ -1026,24 +979,17 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id) > struct aio_ring __user *ring = (void __user *)ctx_id; > struct mm_struct *mm = current->mm; > struct kioctx *ctx, *ret = NULL; > - struct kioctx_table *table; > unsigned id; > > if (get_user(id, &ring->id)) > return NULL; > > rcu_read_lock(); > - table = rcu_dereference(mm->ioctx_table); > - > - if (!table || id >= table->nr) > - goto out; > - > - ctx = rcu_dereference(table->table[id]); > + ctx = xa_load(&mm->ioctx, id); > if (ctx && ctx->user_id == ctx_id) { > if (percpu_ref_tryget_live(&ctx->users)) > ret = ctx; > } Question on this part - do we need that RCU read lock around this now? I don't think we do. -- Jens Axboe