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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEC4AC433F5 for ; Sun, 6 Mar 2022 03:52:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 212FD6B0071; Sat, 5 Mar 2022 22:52:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C2476B0072; Sat, 5 Mar 2022 22:52:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0B2BC6B0073; Sat, 5 Mar 2022 22:52:27 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id EFB4D6B0071 for ; Sat, 5 Mar 2022 22:52:26 -0500 (EST) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id BBB38942 for ; Sun, 6 Mar 2022 03:52:26 +0000 (UTC) X-FDA: 79212589092.07.A65A3B3 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf02.hostedemail.com (Postfix) with ESMTP id 0BED580003 for ; Sun, 6 Mar 2022 03:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=9sW6PT9UhN7TdCknrB4vEZzr80Evyo9BiN2TBCQrpu8=; b=mexz5CF+uqowjqVXolKHAmICBZ /gBgallofA7ozgz6jmmxeLDOiLP+ug6bK856a/z+a9w7TUyxkvWlRyWXibD8YaVX9xEhWkvXfvJ0c T9CsFtuhgdywtjyO5X9YgUt7T7PWomuTwyfHCOGFUDiGUHpzGsSie9GdiLq7+5D36BobFZ/yP2NUj qr1wqTzCzqTn0g1ebz0/mAsEBexkspvGujBr22b3rqg8CDfMkfi2+IvRyah//kltQsrveMxB400WD J0XLKsOaVBufmV3UVpDkBZF539qZ0MxKfcyCwprq0N/9p+ZQ6jqDwbiBbdFzFrSEzsOcI1kPbIRAL xGmlkpYw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nQhwK-00E56f-PJ; Sun, 06 Mar 2022 03:52:12 +0000 Date: Sun, 6 Mar 2022 03:52:12 +0000 From: Matthew Wilcox To: Jarkko Sakkinen Cc: Andrew Morton , Dave Hansen , Nathaniel McCallum , Reinette Chatre , linux-sgx@vger.kernel.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, codalist@coda.cs.cmu.edu, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH RFC] mm: Add f_ops->populate() Message-ID: References: <20220306021534.83553-1-jarkko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 0BED580003 X-Stat-Signature: 3zqhsg8iwu64zysjoiqrgapka8zcy8w9 Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=mexz5CF+; spf=none (imf02.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-HE-Tag: 1646538745-181848 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Mar 06, 2022 at 05:21:11AM +0200, Jarkko Sakkinen wrote: > On Sun, Mar 06, 2022 at 02:57:55AM +0000, Matthew Wilcox wrote: > > On Sun, Mar 06, 2022 at 04:15:33AM +0200, Jarkko Sakkinen wrote: > > > Sometimes you might want to use MAP_POPULATE to ask a device driver to > > > initialize the device memory in some specific manner. SGX driver can use > > > this to request more memory by issuing ENCLS[EAUG] x86 opcode for each > > > page in the address range. > > > > > > Add f_ops->populate() with the same parameters as f_ops->mmap() and make > > > it conditionally called inside call_mmap(). Update call sites > > > accodingly. > > > > Your device driver has a ->mmap operation. Why does it need another > > one? More explanation required here. > > f_ops->mmap() would require an additional parameter, which results > heavy refactoring. > > struct file_operations has 1125 references in the kernel tree, so I > decided to check this way around first. Are you saying that your device driver behaves differently if MAP_POPULATE is set versus if it isn't? That seems hideously broken.