Received: by 2002:a05:6a10:5bc5:0:0:0:0 with SMTP id os5csp1765543pxb;
        Thu, 4 Nov 2021 08:05:20 -0700 (PDT)
X-Google-Smtp-Source: ABdhPJzvSlguaI+qnGu5c+qslYNmW17iG9XM1uWPlRevAyHT0PY7RYorOVhOmZH5ivEpK4nPeA7d
X-Received: by 2002:a05:6e02:178d:: with SMTP id y13mr36238729ilu.0.1636038319985;
        Thu, 04 Nov 2021 08:05:19 -0700 (PDT)
ARC-Seal: i=1; a=rsa-sha256; t=1636038319; cv=none;
        d=google.com; s=arc-20160816;
        b=0QvmLPaRZygEmow1r/mm1+Xgzy5xm7SAtghGhePg3DrOoWfCFlEwhSt5VrzoFI8YCu
         Wblt9yzEMm3Puuij0RdYa8ysJQduEz8RhtZx/SCCSOMVEDuB7B8VB3n2MkqY+7x4COXP
         zmQ+u2+9bQ3Hg3Kne0CByrmP2vDfHWxT9aS8k89arJTskfFMYeCch5iXvatxIYMYWXXB
         4laVBIfqxm1jNGHL97PQ8sfNjd5hnkp7hMI+zwljDo1MH/uEsfg+Z2UP7m3Cozsz1J4r
         WNt6oj0DeEC6PF9Jep4UciiniEWWztBDTAW1s1M63gbpdgHqZEOqJGkX0bL7HRjBuPtO
         YA0A==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;
        h=list-id:precedence:content-disposition:mime-version:message-id
         :subject:cc:to:from:date:dkim-signature;
        bh=ZTxXopUmkY1B4mLUzgPVJBNJwKWxxnzj2Sovw24wOoc=;
        b=o98yMgO30VdaIwy7XLJ4C4zefyQVpGlVJ+10pw370cnmFv7G1rF7PQSaFC+ht2Jpye
         EaRNv0WZI4EJG9vTSfE6K96AY9vbcTqERBBtNaLyEgW+EtYlvKttOymVPF2KJBQ1v9Tq
         kzuoJJOJjtbwSdqDMJx0oFkW87rD2JpzLVyqI/XALAlgdlM8y0uCFJZPdGps+kGsNGF7
         nugP1NPYDc3jYFCvGikl9FpxyaiDi4XiMdLpXrm6gMwE8ikJeaHwRrngiD/I9OODPBXm
         dtrracMPIUpvzS2PdjOoMjtD2Vfs1pOoQyFfWYe35Kee3DLo8stnE2w5Rt0gYaoaVDeA
         SIkg==
ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass header.i=@infradead.org header.s=casper.20170209 header.b=kNcXKRBS;
       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: <linux-kernel-owner@vger.kernel.org>
Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18])
        by mx.google.com with ESMTP id a13si4292506ilv.53.2021.11.04.08.04.56;
        Thu, 04 Nov 2021 08:05:19 -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=@infradead.org header.s=casper.20170209 header.b=kNcXKRBS;
       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 S231311AbhKDPGP (ORCPT <rfc822;ly15351151@gmail.com> + 99 others);
        Thu, 4 Nov 2021 11:06:15 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51606 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S229920AbhKDPGN (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 4 Nov 2021 11:06:13 -0400
Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC8EFC061714;
        Thu,  4 Nov 2021 08:03:35 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;
        d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:Message-ID:
        Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID:
        Content-Description:In-Reply-To:References;
        bh=ZTxXopUmkY1B4mLUzgPVJBNJwKWxxnzj2Sovw24wOoc=; b=kNcXKRBS3xPEMduGlZBk7OiC4l
        UlIRsZ/HYitqc0YSiAfQiNxmg89EqIttpiT4eJHxAwffCnNTDbdaFkJGrikp/c3XYgyP6QljYld9i
        ug6w9H7556vzkvMcfygGkzj7e/bu+NrZp3lAfE1+uYuu0Mvi9ufMbsIQinP27Eku2KLVso0p6iEyH
        ePyJ/CBi62bJq+w0JafU4jyLi1dzE4Kq7meWAr/gJfozu9XcRfmP3N3Dxe1Jh3HtKbiTDz52XX/Ws
        I5vinVxtKVg8mj/F7GpI9NncAd11fTK2HS3pF65G5TgeQBoAqwdmCJ5cpi1CIinZWC6n82yRSRz/M
        SD0hvNyQ==;
Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux))
        id 1mieEG-005wYd-CL; Thu, 04 Nov 2021 15:01:40 +0000
Date:   Thu, 4 Nov 2021 15:00:36 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>
Cc:     linux-arch@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>
Subject: flush_dcache_page vs kunmap_local
Message-ID: <YYP1lAq46NWzhOf0@casper.infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

In https://lore.kernel.org/lkml/CAHk-=wijdojzo56FzYqE5TOYw2Vws7ik3LEMGj9SPQaJJ+Z73Q@mail.gmail.com/
Linus offers the opinion that kunmap calls should imply a
flush_dcache_page().  Christoph added calls to flush_dcache_page()
in commit 8dad53a11f8d.  Was this "voodoo programming", or was there
a real problem being addressed?