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Open Source and information security mailing list archives
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Date: Mon, 12 Oct 2020 09:19:46 -0700 From: Eric Biggers <ebiggers@...nel.org> To: Ira Weiny <ira.weiny@...el.com> Cc: Matthew Wilcox <willy@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, linux-aio@...ck.org, linux-efi@...r.kernel.org, kvm@...r.kernel.org, linux-doc@...r.kernel.org, linux-mmc@...r.kernel.org, Dave Hansen <dave.hansen@...ux.intel.com>, dri-devel@...ts.freedesktop.org, linux-mm@...ck.org, target-devel@...r.kernel.org, linux-mtd@...ts.infradead.org, linux-kselftest@...r.kernel.org, samba-technical@...ts.samba.org, ceph-devel@...r.kernel.org, drbd-dev@...ts.linbit.com, devel@...verdev.osuosl.org, linux-cifs@...r.kernel.org, linux-nilfs@...r.kernel.org, linux-scsi@...r.kernel.org, linux-nvdimm@...ts.01.org, linux-rdma@...r.kernel.org, x86@...nel.org, amd-gfx@...ts.freedesktop.org, linux-afs@...ts.infradead.org, cluster-devel@...hat.com, linux-cachefs@...hat.com, intel-wired-lan@...ts.osuosl.org, xen-devel@...ts.xenproject.org, linux-ext4@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>, ecryptfs@...r.kernel.org, linux-um@...ts.infradead.org, intel-gfx@...ts.freedesktop.org, linux-erofs@...ts.ozlabs.org, reiserfs-devel@...r.kernel.org, linux-block@...r.kernel.org, linux-bcache@...r.kernel.org, Jaegeuk Kim <jaegeuk@...nel.org>, Dan Williams <dan.j.williams@...el.com>, io-uring@...r.kernel.org, linux-nfs@...r.kernel.org, linux-ntfs-dev@...ts.sourceforge.net, netdev@...r.kernel.org, kexec@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net, linux-fsdevel@...r.kernel.org, bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-btrfs@...r.kernel.org Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread() 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
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