From patchwork Fri Aug 12 22:56:33 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Keith Busch X-Patchwork-Id: 12942601 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 DFA2FC00140 for ; Fri, 12 Aug 2022 22:57:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237585AbiHLW47 (ORCPT ); Fri, 12 Aug 2022 18:56:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229966AbiHLW46 (ORCPT ); Fri, 12 Aug 2022 18:56:58 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E28195AFF for ; Fri, 12 Aug 2022 15:56:58 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 27CF7ScT031520 for ; Fri, 12 Aug 2022 15:56:58 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=lNezAUv7WCHsX1C/AGGoqibiE8HHJGLoSMIFGTx7aGk=; b=CXQb3/aP973fFN1kHM65LugRSp+dm7ejoNFH76Tdxk4xrEmb8FSZWBJrAVzDi5r7y4AT LzEyNhdnrV0KxBGVGDhnNIHsDZxCbC60YlNPFhMnyGBh3axHGn3T71Tl3D8JEg7E5XLg jWvUE1p6OV/uikcj/5pZU0DD1wYtRRILI3o= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3hw9geqtkg-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 12 Aug 2022 15:56:58 -0700 Received: from twshared20276.35.frc1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 12 Aug 2022 15:56:53 -0700 Received: by devbig007.nao1.facebook.com (Postfix, from userid 544533) id 6138074B6525; Fri, 12 Aug 2022 15:56:41 -0700 (PDT) From: Keith Busch To: , CC: , Keith Busch , Linus Torvalds Subject: [PATCH] fs: don't randomized kiocb fields Date: Fri, 12 Aug 2022 15:56:33 -0700 Message-ID: <20220812225633.3287847-1-kbusch@fb.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: KweBFYznz-35LJy8C0u1Sty2xvq07_hx X-Proofpoint-GUID: KweBFYznz-35LJy8C0u1Sty2xvq07_hx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-12_10,2022-08-11_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 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. Suggested-by: Linus Torvalds Signed-off-by: Keith Busch --- include/linux/fs.h | 5 ----- 1 file changed, 5 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 5113f65c786f..9eced4cc286e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -340,17 +340,12 @@ enum rw_hint { struct kiocb { struct file *ki_filp; - - /* The 'ki_filp' pointer is shared in a union for aio */ - randomized_struct_fields_start - loff_t ki_pos; void (*ki_complete)(struct kiocb *iocb, long ret); void *private; int ki_flags; u16 ki_ioprio; /* See linux/ioprio.h */ struct wait_page_queue *ki_waitq; /* for async buffered IO */ - randomized_struct_fields_end }; static inline bool is_sync_kiocb(struct kiocb *kiocb)