Received: by 2002:a05:6a10:206:0:0:0:0 with SMTP id 6csp522845pxj; Thu, 3 Jun 2021 12:28:40 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyVMdEIe/aZyku1sKkCIW6bHi7Y/Mz/1p/ZJfd1PtiuuxdcGKBDUSn6fceaF3ZhPO6dL+F0 X-Received: by 2002:aa7:dd4f:: with SMTP id o15mr1037772edw.174.1622748520324; Thu, 03 Jun 2021 12:28:40 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1622748520; cv=none; d=google.com; s=arc-20160816; b=wxc8pXd86UB9JWY7rg0J+ZlW65F+8kYFLfuqCYv+YwtfsNA5+aHYN1I1nkOnNRsaOH R+XIWqOhoQdtzKkk8KCvmU1VdwJXbWbTBw9sgael7VgYotkBPpdOwiIAdsyg/w2ca5ck /De6gmwC2kz6ev59aIEfI2jRXsry8ZYQS5w7K/ppx6bucSXKRCixGEc7ETi74pnS7B5b rbf9OprctmvH6Vf+XWl15jjNbrFe6ULafxK7Kj/vXxMfhl7D513OE4DSB6RQkN13j9De e9wdgdeSTHGWr7q0VfkqDLqSeeKJCXt51OTBZktUoYg3NKdmXQEi0oe/aqrSvJpzvgMJ 8fcA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:to:in-reply-to:cc:references:message-id:date :subject:mime-version:from:content-transfer-encoding:dkim-signature; bh=VKOvv1TfivesDpA9bfyoNG/IGgKCAjb7/e1zzaiAOEk=; b=TJxE6/X5pNggZIcPJO6ktqI0idb4D2k1MuCeLyns8Pr+lnasKyvKeAOE4iEvcYTC4+ KVBFfB7OtNNQhtAF1vyBXpT5UREydi9opXcEP/kphkl9Yq+Y+yQ8cvPUyVaiTXuaagRY YS6cDK3hV6y+FgBkSYgFRoQ9EXb42nySRn5tuGYe47LqvMFoKER40aZX57NzRQP8d3H6 AOYiEEgDfi3nTHMlVHFmyAz1ixYR2cf2f7jUZSWhGjHm4QotlPoIyyLZ85E+qstwFO1c VvronZznmslrd1+u/n1Cjtix5mruwwR+SdEr22N4fVVfp4GSfhGiUggNwaKCbgBjt92d O1sw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@amacapital-net.20150623.gappssmtp.com header.s=20150623 header.b=YHJtOqmP; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id o7si2864669edq.367.2021.06.03.12.28.16; Thu, 03 Jun 2021 12:28:40 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@amacapital-net.20150623.gappssmtp.com header.s=20150623 header.b=YHJtOqmP; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229736AbhFCT0o (ORCPT + 99 others); Thu, 3 Jun 2021 15:26:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229617AbhFCT0o (ORCPT ); Thu, 3 Jun 2021 15:26:44 -0400 Received: from mail-pf1-x430.google.com (mail-pf1-x430.google.com [IPv6:2607:f8b0:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8CC0C06174A for ; Thu, 3 Jun 2021 12:24:59 -0700 (PDT) Received: by mail-pf1-x430.google.com with SMTP id d16so5631149pfn.12 for ; Thu, 03 Jun 2021 12:24:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=VKOvv1TfivesDpA9bfyoNG/IGgKCAjb7/e1zzaiAOEk=; b=YHJtOqmPmvkFRQD2wSYjf5pEKJlBfTPGaQOnmvD/5Z9Y4F5422uvqf19ecqh+AZHI8 yAVvX4M8R1gI6PVHLKRqdskhOY3wedR4+hxBr18GaFfPA/pR52s6ev3ZvjQj8A45N1Fx U389vkuek419vpSY0Lgx/aC0pjQ6UHGKHXs0wAy1tUHt/hVdhxBn1Xmt3Q0vDEEbk2gt rSmuBEXFguqfGN2nqGbExMh2omMlRV9s8qDzIsBBpxkKAdz9Jrdi5vmtaaZtw//SVwNO gaQTYGHkxnc/EpICvm1ylvW4QsOvmk05/ZVNMKMo3HBcx3RqJv3RtxBueIbs2U8JMwGH PRNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=VKOvv1TfivesDpA9bfyoNG/IGgKCAjb7/e1zzaiAOEk=; b=ITVhI2kYfu6vdXe585Q13LlasvL1IhmVqliKRgx3TQFc48mz9fniyFgIJDX5N9Nr8l 0YwiYVNo9JdzW4J6pXQ4+zW8wsp7N2ETKh6cfegXWeL5o2mZcVUFbl6aXMdrbgQ6QTvD pUbxfnQCOctIsUKQTO50xfNz5Vq5HvliMbF8qJ2BwMGxvnP55meT34sY/+jsl3XLrovi h8dCRid0FIzLuaG6RGiVUZG1zqJVd+VSUQov/qw1H0aEEC5Rs0tTszKvdaRnwBhEpE3U nCAvXLtNfbm+sDtVZbGHDobluJMuXPu/cxae1HG0htStaVRouqIT1ODF1oXA/E0SOM76 DjJQ== X-Gm-Message-State: AOAM533Q4gwFiaZdYiXSMQM8V3TaQQutCOKdxzSKrGXuu4qYY5zuLt8m 61wkRH9JxE8bMcd5P45ia+QakQaXTPlATQ== X-Received: by 2002:a62:2e04:0:b029:2db:4c99:614f with SMTP id u4-20020a622e040000b02902db4c99614fmr575083pfu.47.1622748299253; Thu, 03 Jun 2021 12:24:59 -0700 (PDT) Received: from smtpclient.apple ([2600:1010:b04a:17e9:b873:a3cc:f7b1:9d6d]) by smtp.gmail.com with ESMTPSA id n23sm3300321pgv.76.2021.06.03.12.24.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 03 Jun 2021 12:24:58 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [PATCH 2/2] mm: adds NOSIGBUS extension for out-of-band shmem read Date: Thu, 3 Jun 2021 12:24:56 -0700 Message-Id: <1FD047D2-F5F3-4AC6-A4E4-DB8FB1568821@amacapital.net> References: Cc: Hugh Dickins , Ming Lin , Simon Ser , Linux-MM , Linux Kernel Mailing List , linux-fsdevel , Linux API In-Reply-To: To: Linus Torvalds X-Mailer: iPhone Mail (18E212) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jun 3, 2021, at 12:14 PM, Linus Torvalds wrote: >=20 > =EF=BB=BFOn Thu, Jun 3, 2021 at 12:07 PM Hugh Dickins w= rote: >>=20 >> But the point that we've arrived at, that I'm actually now fairly >> happy with, is do *not* permit MAP_NOSIGBUS on MAP_SHARED mappings. >=20 > Yeah, if that's sufficient, then that original patch should just work as-i= s. >=20 > But there was some reason why people didn't like that patch > originally, and I think it was literally about how it only worked on > private mappings (the "we don't have a flag for it in the vm_flags" > part was just a small detail. >=20 > I guess that objection ended up changing over time. >=20 >=20 I don=E2=80=99t understand the use case well enough to comment on whether MA= P_PRIVATE is sufficient, but I=E2=80=99m with Hugh: if this feature is imple= mented for MAP_SHARED, it should be fully coherent.=