mm: add mmap_action_map_kernel_pages[_full]()

A user can invoke mmap_action_map_kernel_pages() to specify that the
mapping should map kernel pages starting from desc->start of a specified
number of pages specified in an array.

In order to implement this, adjust mmap_action_prepare() to be able to
return an error code, as it makes sense to assert that the specified
parameters are valid as quickly as possible as well as updating the VMA
flags to include VMA_MIXEDMAP_BIT as necessary.

This provides an mmap_prepare equivalent of vm_insert_pages().  We
additionally update the existing vm_insert_pages() code to use
range_in_vma() and add a new range_in_vma_desc() helper function for the
mmap_prepare case, sharing the code between the two in range_is_subset().

We add both mmap_action_map_kernel_pages() and
mmap_action_map_kernel_pages_full() to allow for both partial and full VMA
mappings.

We update the documentation to reflect the new features.

Finally, we update the VMA tests accordingly to reflect the changes.

Link: https://lkml.kernel.org/r/926ac961690d856e67ec847bee2370ab3c6b9046.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/filesystems/mmap_prepare.rst b/Documentation/filesystems/mmap_prepare.rst
index 14bb057be564..82c99c95ad85 100644
--- a/Documentation/filesystems/mmap_prepare.rst
+++ b/Documentation/filesystems/mmap_prepare.rst
@@ -156,5 +156,13 @@ pointer. These are:
 * mmap_action_simple_ioremap() - Sets up an I/O remap from a specified
   physical address and over a specified length.
 
+* mmap_action_map_kernel_pages() - Maps a specified array of `struct page`
+  pointers in the VMA from a specific offset.
+
+* mmap_action_map_kernel_pages_full() - Maps a specified array of `struct
+  page` pointers over the entire VMA. The caller must ensure there are
+  sufficient entries in the page array to cover the entire range of the
+  described VMA.
+
 **NOTE:** The ``action`` field should never normally be manipulated directly,
 rather you ought to use one of these helpers.