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Re: [PATCH RFC PKS/PMEM 24/58] fs/freevxfs: Utilize new kmap_thread()
 
- To: ira.weiny@xxxxxxxxx
 
- From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
 
- Date: Tue, 13 Oct 2020 12:25:44 +0100
 
- Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>,	Thomas Gleixner <tglx@xxxxxxxxxxxxx>,	Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>,	Andy Lutomirski <luto@xxxxxxxxxx>,	Peter Zijlstra <peterz@xxxxxxxxxxxxx>,	Christoph Hellwig <hch@xxxxxxxxxxxxx>, x86@xxxxxxxxxx,	Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>,	Dan Williams <dan.j.williams@xxxxxxxxx>,	Fenghua Yu <fenghua.yu@xxxxxxxxx>, linux-doc@xxxxxxxxxxxxxxx,	linux-kernel@xxxxxxxxxxxxxxx, linux-nvdimm@xxxxxxxxxxxx,	linux-fsdevel@xxxxxxxxxxxxxxx, linux-mm@xxxxxxxxx,	linux-kselftest@xxxxxxxxxxxxxxx, linuxppc-dev@xxxxxxxxxxxxxxxx,	kvm@xxxxxxxxxxxxxxx, netdev@xxxxxxxxxxxxxxx, bpf@xxxxxxxxxxxxxxx,	kexec@xxxxxxxxxxxxxxxxxxx, linux-bcache@xxxxxxxxxxxxxxx,	linux-mtd@xxxxxxxxxxxxxxxxxxx, devel@xxxxxxxxxxxxxxxxxxxx,	linux-efi@xxxxxxxxxxxxxxx, linux-mmc@xxxxxxxxxxxxxxx,	linux-scsi@xxxxxxxxxxxxxxx, target-devel@xxxxxxxxxxxxxxx,	linux-nfs@xxxxxxxxxxxxxxx, ceph-devel@xxxxxxxxxxxxxxx,	linux-ext4@xxxxxxxxxxxxxxx, linux-aio@xxxxxxxxx,	io-uring@xxxxxxxxxxxxxxx, linux-erofs@xxxxxxxxxxxxxxxx,	linux-um@xxxxxxxxxxxxxxxxxxx, linux-ntfs-dev@xxxxxxxxxxxxxxxxxxxxx,	reiserfs-devel@xxxxxxxxxxxxxxx,	linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx, linux-nilfs@xxxxxxxxxxxxxxx,	cluster-devel@xxxxxxxxxx, ecryptfs@xxxxxxxxxxxxxxx,	linux-cifs@xxxxxxxxxxxxxxx, linux-btrfs@xxxxxxxxxxxxxxx,	linux-afs@xxxxxxxxxxxxxxxxxxx, linux-rdma@xxxxxxxxxxxxxxx,	amd-gfx@xxxxxxxxxxxxxxxxxxxxx, dri-devel@xxxxxxxxxxxxxxxxxxxxx,	intel-gfx@xxxxxxxxxxxxxxxxxxxxx, drbd-dev@xxxxxxxxxxxxxxxx,	linux-block@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx,	linux-cachefs@xxxxxxxxxx, samba-technical@xxxxxxxxxxxxxxx,	intel-wired-lan@xxxxxxxxxxxxxxxx
 
- Delivery-date: Tue, 13 Oct 2020 11:26:45 +0000
 
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
 
 
 
> -     kaddr = kmap(pp);
> +     kaddr = kmap_thread(pp);
>       memcpy(kaddr, vip->vii_immed.vi_immed + offset, PAGE_SIZE);
> -     kunmap(pp);
> +     kunmap_thread(pp);
You only Cced me on this particular patch, which means I have absolutely
no idea what kmap_thread and kunmap_thread actually do, and thus can't
provide an informed review.
That being said I think your life would be a lot easier if you add
helpers for the above code sequence and its counterpart that copies
to a potential hughmem page first, as that hides the implementation
details from most users.
 
 
    
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