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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F4C3C00140 for ; Fri, 12 Aug 2022 23:00:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234827AbiHLXAV (ORCPT ); Fri, 12 Aug 2022 19:00:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39160 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229966AbiHLXAV (ORCPT ); Fri, 12 Aug 2022 19:00:21 -0400 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B67827B2A for ; Fri, 12 Aug 2022 16:00:20 -0700 (PDT) Received: by mail-pg1-x52c.google.com with SMTP id 24so1926993pgr.7 for ; Fri, 12 Aug 2022 16:00:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=pUNWkjszMYZBFHroYs6rd5N4Fu75mFK6lm079OKJfbw=; b=OBoh4QL9dNHnWIhTale1OJxVwy9QLsmWe0VqGHE6v9FfWqZ64XnP34avtT0Q54c3Mb kWOzDrPK2HIuQZmvUwG5lCNYwroiOl1TmusXrkGhRYaLXBnSBCOeoW1+aWS+18taEIov VQvorfcYsfy49x/8ClIr23LIuDAnTPF8PCdMFRkMv1YJaDyiBJCgtc9gkDkj5gmFYAzE d8FUddaGRxhJWDv+q4+1Bob+Z3fa1NgL7q56HNnKsmRHma712o/ACQtzN9UeubDfWNMN h1pIIsXMlKbS8YULKM+8L/kpyZcpyk/xpOVQsO49Rn3WC+fx+sAFUTWmorrho6nDXllU FEyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=pUNWkjszMYZBFHroYs6rd5N4Fu75mFK6lm079OKJfbw=; b=oXWNs2XOlcESJFoE/VJjt0Oidiq+wzf39fQAnW0gUqRoiyEBTO6maP2FBRQHpouzRM k2NGuQMmWIH5ZIcDBlmEFEs5PdnGlp5/mRyNiZtQrozzR29OeyvGOdi6pPcV8GhuWy+6 t09rlyzildaNLhtxDjUB6jAO86VWH+nKFVgbsHSVkZU8cOJWnvjNMHYGrVSP6gmE8KUU YD1TkTJM4CHZKRcCNReqx27nnUn1Byd5wqKRWpTddIwajB50bejPuiC72KxnRdXATyB7 E6TOJJWqsdwrqnwMbaeMGiRBK4Nd5/QBrCBv2FsL9M/flZngrnRpTX02J4bZ1Dtf8rVs mlGw== X-Gm-Message-State: ACgBeo39KkfPbAKS+Ly/BSNE0dlq7D1nZ4I5A+77BFBR4vZqYp5u/is8 wvS/3ZGBpydffOyNLRBuGfYUmg== X-Google-Smtp-Source: AA6agR7Vr48zlj57DBqPlIRW0ba5Ne9nYim2sIjAYqqFP4Rl660T7yUBFmfS/tZVcKR3Mb3DIQZp5A== X-Received: by 2002:a65:6bca:0:b0:420:712f:ab98 with SMTP id e10-20020a656bca000000b00420712fab98mr4850132pgw.350.1660345219685; Fri, 12 Aug 2022 16:00:19 -0700 (PDT) Received: from [192.168.1.100] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id q8-20020a170902788800b0016d6420691asm2268554pll.207.2022.08.12.16.00.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Aug 2022 16:00:19 -0700 (PDT) Message-ID: <8773ef66-e6a4-ed64-71ed-837cac5341f5@kernel.dk> Date: Fri, 12 Aug 2022 17:00:18 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH] fs: don't randomized kiocb fields Content-Language: en-US To: Keith Busch , io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, Keith Busch , Linus Torvalds References: <20220812225633.3287847-1-kbusch@fb.com> From: Jens Axboe In-Reply-To: <20220812225633.3287847-1-kbusch@fb.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 8/12/22 4:56 PM, Keith Busch wrote: > From: Keith Busch > > This is a size sensitive structure and randomizing can introduce extra > padding that breaks io_uring's fixed size expectations. There are few > fields here as it is, half of which need a fixed order to optimally > pack, so the randomization isn't providing much. I'll add the link to the previous discussion as well in the commit: Link: https://lore.kernel.org/io-uring/b6f508ca-b1b2-5f40-7998-e4cff1cf7212@kernel.dk/ as it's pretty useful for context. -- Jens Axboe