Merge branch 'hmm-devmem-cleanup.4' into rdma.git hmm

Christoph Hellwig says:

====================
Below is a series that cleans up the dev_pagemap interface so that it is
more easily usable, which removes the need to wrap it in hmm and thus
allowing to kill a lot of code

Changes since v3:
 - pull in "mm/swap: Fix release_pages() when releasing devmap pages" and
   rebase the other patches on top of that
 - fold the hmm_devmem_add_resource into the DEVICE_PUBLIC memory removal
   patch
 - remove _vm_normal_page as it isn't needed without DEVICE_PUBLIC memory
 - pick up various ACKs

Changes since v2:
 - fix nvdimm kunit build
 - add a new memory type for device dax
 - fix a few issues in intermediate patches that didn't show up in the end
   result
 - incorporate feedback from Michal Hocko, including killing of
   the DEVICE_PUBLIC memory type entirely

Changes since v1:
 - rebase
 - also switch p2pdma to the internal refcount
 - add type checking for pgmap->type
 - rename the migrate method to migrate_to_ram
 - cleanup the altmap_valid flag
 - various tidbits from the reviews
====================

Conflicts resolved by:
 - Keeping Ira's version of the code in swap.c
 - Using the delete for the section in hmm.rst
 - Using the delete for the devmap code in hmm.c and .h

* branch 'hmm-devmem-cleanup.4': (24 commits)
  mm: don't select MIGRATE_VMA_HELPER from HMM_MIRROR
  mm: remove the HMM config option
  mm: sort out the DEVICE_PRIVATE Kconfig mess
  mm: simplify ZONE_DEVICE page private data
  mm: remove hmm_devmem_add
  mm: remove hmm_vma_alloc_locked_page
  nouveau: use devm_memremap_pages directly
  nouveau: use alloc_page_vma directly
  PCI/P2PDMA: use the dev_pagemap internal refcount
  device-dax: use the dev_pagemap internal refcount
  memremap: provide an optional internal refcount in struct dev_pagemap
  memremap: replace the altmap_valid field with a PGMAP_ALTMAP_VALID flag
  memremap: remove the data field in struct dev_pagemap
  memremap: add a migrate_to_ram method to struct dev_pagemap_ops
  memremap: lift the devmap_enable manipulation into devm_memremap_pages
  memremap: pass a struct dev_pagemap to ->kill and ->cleanup
  memremap: move dev_pagemap callbacks into a separate structure
  memremap: validate the pagemap type passed to devm_memremap_pages
  mm: factor out a devm_request_free_mem_region helper
  mm: export alloc_pages_vma
  ...

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

diff --cc Documentation/vm/hmm.rst
index 7b6eeda,50e1380..7d90964
--- 1/Documentation/vm/hmm.rst
--- 2/Documentation/vm/hmm.rst
+++ b/Documentation/vm/hmm.rst
@@@ -336,33 -329,7 +336,6 @@@ directly using struct page for device m
  unaware of the difference. We only need to make sure that no one ever tries to
  map those pages from the CPU side.
  
- HMM provides a set of helpers to register and hotplug device memory as a new
- region needing a struct page. This is offered through a very simple API::
- 
-  struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
-                                    struct device *device,
-                                    unsigned long size);
-  void hmm_devmem_remove(struct hmm_devmem *devmem);
- 
- The hmm_devmem_ops is where most of the important things are::
- 
-  struct hmm_devmem_ops {
-      void (*free)(struct hmm_devmem *devmem, struct page *page);
-      vm_fault_t (*fault)(struct hmm_devmem *devmem,
-                   struct vm_area_struct *vma,
-                   unsigned long addr,
-                   struct page *page,
-                   unsigned flags,
-                   pmd_t *pmdp);
-  };
- 
- The first callback (free()) happens when the last reference on a device page is
- dropped. This means the device page is now free and no longer used by anyone.
- The second callback happens whenever the CPU tries to access a device page
- which it cannot do. This second callback must trigger a migration back to
- system memory.
- 
--
  Migration to and from device memory
  ===================================
  

diff --cc include/linux/hmm.h
Simple merge

diff --cc mm/hmm.c
index c1bdcef,d62ce64..d48b928
--- 1/mm/hmm.c
--- 2/mm/hmm.c
+++ b/mm/hmm.c
@@@ -26,11 -25,18 +26,8 @@@
  #include <linux/mmu_notifier.h>
  #include <linux/memory_hotplug.h>
  
- #define PA_SECTION_SIZE (1UL << PA_SECTION_SHIFT)
- 
- #if IS_ENABLED(CONFIG_HMM_MIRROR)
  static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
  
 -static inline struct hmm *mm_get_hmm(struct mm_struct *mm)
 -{
 -      struct hmm *hmm = READ_ONCE(mm->hmm);
 -
 -      if (hmm && kref_get_unless_zero(&hmm->kref))
 -              return hmm;
 -
 -      return NULL;
 -}
 -
  /**
   * hmm_get_or_create - register HMM against an mm (HMM internal)
   *