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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E990FC433B4 for ; Thu, 29 Apr 2021 18:38:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B937461408 for ; Thu, 29 Apr 2021 18:38:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241080AbhD2Sjb (ORCPT ); Thu, 29 Apr 2021 14:39:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46360 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241002AbhD2Sj3 (ORCPT ); Thu, 29 Apr 2021 14:39:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619721522; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1FDmqgWkaEalBf06QFmezW699riW5RcrkfNE1Srusv0=; b=WeoRH7J16PszCdMGYY/74rRZfOMOBMZp4eTZ5Gr9nQPPNYOECD2NDFUGZJYF2y/vdXXtaZ DgHP80uLEWaJ5oDVpnFB8Z+tLCSCC5K27bN+Oa+SVhFm0norwAAQGchVLRdnVgx45eqBKg imYuC4quPvFNSsa5Sw+izVWPZ9yH8TM= Received: from mail-qt1-f200.google.com (mail-qt1-f200.google.com [209.85.160.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-587-KULflg3ZMYuTjPiqnuX6dQ-1; Thu, 29 Apr 2021 14:38:37 -0400 X-MC-Unique: KULflg3ZMYuTjPiqnuX6dQ-1 Received: by mail-qt1-f200.google.com with SMTP id w10-20020ac86b0a0000b02901ba74ac38c9so15939185qts.22 for ; Thu, 29 Apr 2021 11:38:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=1FDmqgWkaEalBf06QFmezW699riW5RcrkfNE1Srusv0=; b=QSexk+suR32JnKYf7AzGTGnbljWcexrFTN+xE2s3lO9BMsQqXIWfPfzf3mnWgYKg0C F6l9CNo3h2Q4JoGpF+LynMXkXORzgY7uoczjVuRNWpwSPYAKA8x6+ofgHIYhyJi2Wf1i uEbkj9Mf/L70nGBMsuT/YWQDjOJDa6gweiMrk2+k9DZ+IUS3jBmsFUHqamEsIY4MKYzh S9f1siRDnGWo5rWTqlTw8meLkh5O+JA4AMVt0XKDVWNFTf9U2JGxMn1QFexSMH3pJbR9 djuM75JFR8yDLG0bFdljPR58GAuq1GMyyhERN3fRyOzn08EO7NQcWki96O+tSd/9gy7+ Bulg== X-Gm-Message-State: AOAM533Ej/pqsJWnzSNXg1RmME88sOIT7yOPElqcJO9lgWW+f90I8Npc vkSe2uRVIu7QyDzZch8FixU/p1ULS2y9umdDYRPAVsOq0C/oWJzVb/OiRBlarZDQSqu6p4+I/Uc edrRlRc4x/Utaq31CEOhl4+of X-Received: by 2002:a37:8703:: with SMTP id j3mr1126456qkd.308.1619721517488; Thu, 29 Apr 2021 11:38:37 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz+QbuHIrkUNjZjHOfaVvF6309qJU1ww9koDsWD1bCSocJXPnBrvZ/keB1z4Aghlq84eZOD3w== X-Received: by 2002:a37:8703:: with SMTP id j3mr1126442qkd.308.1619721517267; Thu, 29 Apr 2021 11:38:37 -0700 (PDT) Received: from xz-x1 (bras-base-toroon474qw-grc-77-184-145-104-227.dsl.bell.ca. [184.145.104.227]) by smtp.gmail.com with ESMTPSA id v6sm1869037qkg.94.2021.04.29.11.38.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Apr 2021 11:38:36 -0700 (PDT) Date: Thu, 29 Apr 2021 14:38:36 -0400 From: Peter Xu To: "Kirill A. Shutemov" Cc: Linus Torvalds , Matthew Wilcox , Dan Williams , Simon Ser , "Kirill A. Shutemov" , Will Deacon , Linux Kernel Mailing List , David Herrmann , "linux-mm@kvack.org" , Greg Kroah-Hartman , "tytso@mit.edu" Subject: Re: Sealed memfd & no-fault mmap Message-ID: <20210429183836.GF8339@xz-x1> References: <20210429154807.hptls4vnmq2svuea@box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210429154807.hptls4vnmq2svuea@box> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 29, 2021 at 06:48:07PM +0300, Kirill A. Shutemov wrote: > > Side note: this will only ever work for non-shared mappings. > > I think it's show-stopper for the use-case, no? IIUC, the mappings is used > for communication between a compositor and a client and has to be shared. Yes I had the same doubt.. Besides, we probably don't want to convert all VM_FAULT_SIGBUS to fallback to anonymous pages, as I see that vmf_error() converts mostly everything besides -ENOMEM to VM_FAULT_SIGBUS. Thanks, -- Peter Xu