[v2,0/2] vhost, docs: convert to pin_user_pages(), new "case 5"

Message

John Hubbard June 1, 2020, 5:26 a.m. UTC

This is based on Linux 5.7, plus one prerequisite patch:
   "mm/gup: update pin_user_pages.rst for "case 3" (mmu notifiers)" [1]

Changes since v1: removed references to set_page_dirty*(), in response to
Souptick Joarder's review (thanks!).

Cover letter for v1, edited/updated slightly:

It recently became clear to me that there are some get_user_pages*()
callers that don't fit neatly into any of the four cases that are so
far listed in pin_user_pages.rst. vhost.c is one of those.

Add a Case 5 to the documentation, and refer to that when converting
vhost.c.

Thanks to Jan Kara for helping me (again) in understanding the
interaction between get_user_pages() and page writeback [2].

Note that I have only compile-tested the vhost.c patch, although that
does also include cross-compiling for a few other arches. Any run-time
testing would be greatly appreciated.

[1] https://lore.kernel.org/r/[e-mail]
[2] https://lore.kernel.org/r/[e-mail]

John Hubbard (2):
  docs: mm/gup: pin_user_pages.rst: add a "case 5"
  vhost: convert get_user_pages() --> pin_user_pages()

 Documentation/core-api/pin_user_pages.rst | 18 ++++++++++++++++++
 drivers/vhost/vhost.c                     |  5 ++---
 2 files changed, 20 insertions(+), 3 deletions(-)


base-commit: 3d77e6a8804abcc0504c904bd6e5cdf3a5cf8162