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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 1442FC432C0 for ; Tue, 3 Dec 2019 14:19:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BBE9F206DF for ; Tue, 3 Dec 2019 14:19:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PIlxQ3fa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BBE9F206DF Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5909D6B0558; Tue, 3 Dec 2019 09:19:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 541F26B0559; Tue, 3 Dec 2019 09:19:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 430D86B055A; Tue, 3 Dec 2019 09:19:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0031.hostedemail.com [216.40.44.31]) by kanga.kvack.org (Postfix) with ESMTP id 2BEDE6B0558 for ; Tue, 3 Dec 2019 09:19:31 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 771C4818A07E for ; Tue, 3 Dec 2019 14:19:30 +0000 (UTC) X-FDA: 76224038100.02.tent75_7005bcc6ff049 X-HE-Tag: tent75_7005bcc6ff049 X-Filterd-Recvd-Size: 6848 Received: from mail-wr1-f66.google.com (mail-wr1-f66.google.com [209.85.221.66]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Dec 2019 14:19:29 +0000 (UTC) Received: by mail-wr1-f66.google.com with SMTP id j42so3819973wrj.12 for ; Tue, 03 Dec 2019 06:19:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=FOFIa6orblaZISpLEz8Lqi8PNyCSU/kSBO33EwlZhfU=; b=PIlxQ3faAP1Bpvl0X1LtHKmwzxwpOZGpWPP0PJml6N+Bwmh/1C9iry8Edy0yUPYKE9 wpvaarD/aI3ctWHzAAB+RGD3UyxQVk5N6PXspgRCjPx28RsOebaViuggHnEo2Ksj235m 31d1p+a8eErE+9hdX2Bj3+TnJZYpzmlAQ6LUsPerUGsLlSXvILiDEf/iRNDjAEMKeaUM tvO1qiL9D50qJKj5MEtpuhxC8u59pEZ5IM64FrVP5V2S8nwH21HV9eZez8gds2g97CYW veQw27SLV+3vuVTPEheBVCAhf96pz4Xvt5WpQsueP81rzJQxr6egFkvrsrOfiTHisKRJ kOTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=FOFIa6orblaZISpLEz8Lqi8PNyCSU/kSBO33EwlZhfU=; b=VRTerolQX9WU/J3rV7slhfG+dgn0jkrV5KEBCg/WuRW+u/W4mqQSmHvSMl6nklK+2J ePp64D2RlJhbEvowKierMgHueei4qguMyF5DJny9fJRIRY7Mr23ax/kwNWGaZBvRiDIr YSM0RmRF9UkEZPsBWRvAXo+bmYoE5MgMBm0jdxop+wj0uINb5ZKXjGXIMD0/Wdiaf/y6 d3ZQDnPvbvBzQA1iEE/O6amdU6eaJez2Fi0XrjTVna+mYrGqkZ640btOs+q6kT0sgzD2 DaUqUjCUx1Vn9qcA7SzcZ7K7IQHw/Cu7En4Vp3Y4aCH09xeQxBF0tF2zIMLOAjhlcoAA eH9Q== X-Gm-Message-State: APjAAAVC8wdpmlZxi4KDK4Fnw/aNuIRxwOjITpJRJnuCkKQQraR2bZbx DP2SfBdihNnUzBlJIuanFgZnjX2OVVbdIWSC3nW+Xg== X-Google-Smtp-Source: APXvYqyUR6x02dHF1bWEihv8SSz3Sz9qnIc/MuxFcJmG1U5AGKs/6pH6CC9z8kRWx5mdB0X0rz5QdS2zi4QRcuxxqh4= X-Received: by 2002:adf:806e:: with SMTP id 101mr5709362wrk.300.1575382768135; Tue, 03 Dec 2019 06:19:28 -0800 (PST) MIME-Version: 1.0 References: <20191122112621.204798-1-glider@google.com> <20191122112621.204798-26-glider@google.com> In-Reply-To: From: Alexander Potapenko Date: Tue, 3 Dec 2019 15:19:17 +0100 Message-ID: Subject: Re: [PATCH RFC v3 25/36] kmsan: unpoison |tlb| in arch_tlb_gather_mmu() To: Andrey Konovalov Cc: Vegard Nossum , Dmitry Vyukov , Linux Memory Management List , Alexander Viro , Andreas Dilger , Andrew Morton , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Christoph Hellwig , Christoph Hellwig , "Darrick J. Wong" , "David S. Miller" , Dmitry Torokhov , Eric Biggers , Eric Dumazet , Eric Van Hensbergen , Greg Kroah-Hartman , Harry Wentland , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jason Wang , Jens Axboe , Marek Szyprowski , Marco Elver , Mark Rutland , "Martin K. Petersen" , Martin Schwidefsky , Matthew Wilcox , "Michael S . Tsirkin" , Michal Simek , Petr Mladek , Qian Cai , Randy Dunlap , Robin Murphy , Sergey Senozhatsky , Steven Rostedt , Takashi Iwai , "Theodore Ts'o" , Thomas Gleixner , Vasily Gorbik , Wolfram Sang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Nov 29, 2019 at 4:09 PM Andrey Konovalov wr= ote: > > On Fri, Nov 22, 2019 at 12:27 PM wrote: > > > > This is a hack to reduce stackdepot pressure. > > I think this patch needs a better description :) Like in the comment belo= w. > > > > > Signed-off-by: Alexander Potapenko > > To: Alexander Potapenko > > Cc: Vegard Nossum > > Cc: Dmitry Vyukov > > Cc: linux-mm@kvack.org > > > > --- > > > > Change-Id: I22a201e7e4f67ed74f8129072f12e5351b26103a > > --- > > mm/mmu_gather.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > > > diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c > > index 7d70e5c78f97..8c5ea2d2e7d5 100644 > > --- a/mm/mmu_gather.c > > +++ b/mm/mmu_gather.c > > @@ -1,6 +1,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -206,6 +207,15 @@ void tlb_flush_mmu(struct mmu_gather *tlb) > > void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, > > unsigned long start, unsigned long end) > > { > > + /* > > + * TODO(glider): struct mmu_gather contains 7 1-bit fields pack= ed into a > > Remove TODO? Will do, thanks! > > + * 32-bit unsigned int value. The remaining 25 bits remain unin= itialized > > + * and are never used, but KMSAN updates the origin for them in > > + * zap_pXX_range() in mm/memory.c, thus creating very long orig= in > > + * chains. This is technically correct, but consumes too much m= emory. > > + * Unpoisoning the whole structure will prevent creating such c= hains. > > + */ > > + kmsan_unpoison_shadow(tlb, sizeof(*tlb)); > > tlb->mm =3D mm; > > > > /* Is it from 0 to ~0? */ > > -- > > 2.24.0.432.g9d3f5f5b63-goog > > --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg