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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201012161946.GA858@sol.localdomain> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201012_172843_757400_E1242A73 X-CRM114-Status: GOOD ( 14.81 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio@kvack.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, Peter Zijlstra , 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, amd-gfx@lists.freedesktop.org, linux-kselftest@vger.kernel.org, Thomas Gleixner , 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, Matthew Wilcox , linux-afs@lists.infradead.org, cluster-devel@redhat.com, Ingo Molnar , intel-wired-lan@lists.osuosl.org, kexec@lists.infradead.org, xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org, bpf@vger.kernel.org, Dan Williams , Fenghua Yu , intel-gfx@lists.freedesktop.org, ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, Borislav Petkov , Andy Lutomirski , Jaegeuk Kim , ceph-devel@vger.kernel.org, io-uring@vger.kernel.org, linux-cachefs@redhat.com, linux-nfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Andrew Morton , linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On 10/12/20 9:19 AM, Eric Biggers wrote: > 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()? kmap_atomic() is always preferred over kmap()/kmap_thread(). kmap_atomic() is _much_ more lightweight since its TLB invalidation is always CPU-local and never broadcast. So, basically, unless you *must* sleep while the mapping is in place, kmap_atomic() is preferred. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/