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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 51C27C4363A for ; Mon, 12 Oct 2020 16:20:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1EAAF20870 for ; Mon, 12 Oct 2020 16:20:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602519602; bh=FXrMfe87r7In01hy1fZxNUDLVXbtP/5TJ3+XTzWq1o4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=wOCc6ghvKBfSDec0zPRUvNi7cuGaGMEEeqjCcUFFRfHqPoSB/vmLoYlS+ctQlFke7 TBOHvOKlYCVIv6rXTeClTjz1Vp7g99iK8yaJsjrid8m4PeVy43bpnn9zuS5rchnY1l 0so4atFH60jDBew8fx9vfJNRPwtVPlVl4mKtANKU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390316AbgJLQTu (ORCPT ); Mon, 12 Oct 2020 12:19:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:59212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390043AbgJLQTu (ORCPT ); Mon, 12 Oct 2020 12:19:50 -0400 Received: from sol.localdomain (172-10-235-113.lightspeed.sntcca.sbcglobal.net [172.10.235.113]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 22B302080A; Mon, 12 Oct 2020 16:19:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602519589; bh=FXrMfe87r7In01hy1fZxNUDLVXbtP/5TJ3+XTzWq1o4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=V7DSrccLr5b4UIwMLihtwG0wHPpEpEeCdL4DEsryZDNbDbBe/031RRLLs/mkasjte GkozOXCGlriE75ewyNE/y/+1/YN0mvEXF3Fx+zkSk5bqABC19TCsH57zxXZt4yoDfc Gd/Q7Kn6Oc4wJMc886CZx9bFLur2svNEjPDcQyvk= Date: Mon, 12 Oct 2020 09:19:46 -0700 From: Eric Biggers To: Ira Weiny Cc: Matthew Wilcox , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , Peter Zijlstra , linux-aio@kvack.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-mmc@vger.kernel.org, Dave Hansen , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, target-devel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-kselftest@vger.kernel.org, samba-technical@lists.samba.org, ceph-devel@vger.kernel.org, drbd-dev@lists.linbit.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, x86@kernel.org, amd-gfx@lists.freedesktop.org, linux-afs@lists.infradead.org, cluster-devel@redhat.com, linux-cachefs@redhat.com, intel-wired-lan@lists.osuosl.org, xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org, Fenghua Yu , ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, intel-gfx@lists.freedesktop.org, linux-erofs@lists.ozlabs.org, reiserfs-devel@vger.kernel.org, linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, Jaegeuk Kim , Dan Williams , io-uring@vger.kernel.org, linux-nfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, netdev@vger.kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-btrfs@vger.kernel.org Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread() Message-ID: <20201012161946.GA858@sol.localdomain> References: <20201009195033.3208459-1-ira.weiny@intel.com> <20201009195033.3208459-23-ira.weiny@intel.com> <20201009213434.GA839@sol.localdomain> <20201010003954.GW20115@casper.infradead.org> <20201010013036.GD1122@sol.localdomain> <20201012065635.GB2046448@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201012065635.GB2046448@iweiny-DESK2.sc.intel.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Sun, Oct 11, 2020 at 11:56:35PM -0700, Ira Weiny wrote: > > > > And I still don't really understand. After this patchset, there is still code > > nearly identical to the above (doing a temporary mapping just for a memcpy) that > > would still be using kmap_atomic(). > > I don't understand. You mean there would be other call sites calling: > > kmap_atomic() > memcpy() > kunmap_atomic() Yes, there are tons of places that do this. Try 'git grep -A6 kmap_atomic' and look for memcpy(). Hence why I'm asking what will be the "recommended" way to do this... kunmap_thread() or kmap_atomic()? > And since I don't know the call site details if there are kmap_thread() calls > which are better off as kmap_atomic() calls I think it is worth converting > them. But I made the assumption that kmap users would already be calling > kmap_atomic() if they could (because it is more efficient). Not necessarily. In cases where either one is correct, people might not have put much thought into which of kmap() and kmap_atomic() they are using. - Eric