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[209.85.208.54]) by smtp.gmail.com with ESMTPSA id nc29sm1058736ejc.10.2021.07.12.12.24.38 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 12 Jul 2021 12:24:38 -0700 (PDT) Received: by mail-ed1-f54.google.com with SMTP id w14so17969335edc.8 for ; Mon, 12 Jul 2021 12:24:38 -0700 (PDT) X-Received: by 2002:a2e:9241:: with SMTP id v1mr639513ljg.48.1626117867421; Mon, 12 Jul 2021 12:24:27 -0700 (PDT) MIME-Version: 1.0 References: <20210712060928.4161649-1-hch@lst.de> In-Reply-To: <20210712060928.4161649-1-hch@lst.de> From: Linus Torvalds Date: Mon, 12 Jul 2021 12:24:11 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: flush_kernel_dcache_page fixes and removal To: Christoph Hellwig Cc: Andrew Morton , "James E.J. Bottomley" , Russell King , Guo Ren , Thomas Bogendoerfer , Nick Hu , Greentime Hu , Vincent Chen , Helge Deller , Yoshinori Sato , Rich Felker , Geoff Levand , Paul Cercueil , Ulf Hansson , Alex Shi , Linux Kernel Mailing List , Linux ARM , linux-csky@vger.kernel.org, "open list:BROADCOM NVRAM DRIVER" , linux-parisc@vger.kernel.org, Linux-sh list , linux-mmc@vger.kernel.org, linux-scsi , Linux-MM , "open list:DOCUMENTATION" Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C44AC700170D X-Stat-Signature: q4bag78jixmbbmn9wur1e7h7qs5htyjd Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b="MJrdQt/x"; dmarc=none; spf=pass (imf02.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.208.50 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-HE-Tag: 1626117879-438489 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 Sun, Jul 11, 2021 at 11:09 PM Christoph Hellwig wrote: > > I think we should just remove it and eat the very minor overhead in > exec rather than confusing poor driver writers. Ack. I think architectures that have virtual caches might want to think about this patch a bit more, but on the whole I can't argue against the "it's badly documented and misused". No sane architecture will care, since dcache will be coherent (there are more issues on the I$ side, but that's a different issue) Linus