mm/zram: route block swap I/O through swap_ops

[blktests-ci]

Pull request for series with
subject: mm/zram: route block swap I/O through swap_ops
version: 1
url: https://patchwork.kernel.org/project/linux-block/list/?series=1111308

[blktests-ci]

Upstream branch: 1d1de89
series: https://patchwork.kernel.org/project/linux-block/list/?series=1111308
version: 1

Pull request is NOT updated. Failed to apply https://patchwork.kernel.org/project/linux-block/list/?series=1111308
error message:

Cmd('git') failed due to: exit code(128)
  cmdline: git am --3way
  stdout: 'Applying: mm/page_io: let block drivers register custom swap I/O ops
Patch failed at 0001 mm/page_io: let block drivers register custom swap I/O ops
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".'
  stderr: 'error: sha1 information is lacking or useless (include/linux/swap.h).
error: could not build fake ancestor
hint: Use 'git am --show-current-patch=diff' to see the failed patch'

conflict: