[PATCH 00/15] hmm: fixes and documentations v4

[jglisse@redhat.com]

From: JA(C)rA'me Glisse <jglisse@redhat.com>

Fixes and improvement to HMM only impact HMM user. Changes since the
last posting:

Allow release callback to wait on any device driver workqueue which
is processing fault without having to worry for deadlock. Some driver
do call migrate_vma() from their page fault workqueue which itself
will trigger calls to mmu_notifier callback. If we take and keep the
HMM semaphore in write mode while calling device driver release call
back then those can not wait on their page fault workqueue as the
workqueue might end up deadlocking (waiting to be able to take the
HMM semaphore in read mode). Avoid this by dropping HMM semaphore
while calling the device driver release callback.

Other changes from previous post are solely typos fixes (in comment
not in code), s/pfns/pfn for one function argument, and usual patch
formatting fixes (also added review tag for review receive so far).

Below are previous cover letter (everything in them are still true):

----------------------------------------------------------------------
cover letter for v3:

Added a patch to fix zombie mm_struct (missing call to mmu notifier
unregister) this was lost in translation at some point. Included all
typos and comments received so far (and even more typos fixes). Added
more comments. Updated individual patch version to reflect changes.

----------------------------------------------------------------------
cover letter for v2:

Removed pointless VM_BUG_ON() cced stable when appropriate and splited
the last patch into _many_ smaller patches to make it easier to review.
The end result is same modulo comments i received so far and the extra
documentation i added while splitting thing up. Below is previous cover
letter (everything in it is still true):
----------------------------------------------------------------------
cover letter for v1:

All patches only impact HMM user, there is no implication outside HMM.

First patch improve documentation to better reflect what HMM is. Second
patch fix #if/#else placement in hmm.h. The third patch add a call on
mm release which helps device driver who use HMM to clean up early when
a process quit. Finaly last patch modify the CPU snapshot and page fault
helper to simplify device driver. The nouveau patchset i posted last
week already depends on all of those patches.

You can find them in a hmm-for-4.17 branch:

git://people.freedesktop.org/~glisse/linux
https://cgit.freedesktop.org/~glisse/linux/log/?h=hmm-for-4.17

JA(C)rA'me Glisse (13):
  mm/hmm: fix header file if/else/endif maze v2
  mm/hmm: unregister mmu_notifier when last HMM client quit v3
  mm/hmm: hmm_pfns_bad() was accessing wrong struct
  mm/hmm: use struct for hmm_vma_fault(), hmm_vma_get_pfns() parameters
    v2
  mm/hmm: remove HMM_PFN_READ flag and ignore peculiar architecture v2
  mm/hmm: use uint64_t for HMM pfn instead of defining hmm_pfn_t to
    ulong v2
  mm/hmm: cleanup special vma handling (VM_SPECIAL)
  mm/hmm: do not differentiate between empty entry or missing directory
    v3
  mm/hmm: rename HMM_PFN_DEVICE_UNADDRESSABLE to HMM_PFN_DEVICE_PRIVATE
  mm/hmm: move hmm_pfns_clear() closer to where it is use
  mm/hmm: factor out pte and pmd handling to simplify hmm_vma_walk_pmd()
    v2
  mm/hmm: change hmm_vma_fault() to allow write fault on page basis
  mm/hmm: use device driver encoding for HMM pfn v2

Ralph Campbell (2):
  mm/hmm: documentation editorial update to HMM documentation
  mm/hmm: HMM should have a callback before MM is destroyed v3

 Documentation/vm/hmm.txt | 360 +++++++++++++++---------------
 MAINTAINERS              |   1 +
 include/linux/hmm.h      | 201 ++++++++++-------
 mm/hmm.c                 | 556 +++++++++++++++++++++++++++++++----------------
 4 files changed, 675 insertions(+), 443 deletions(-)

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2.14.3