Commit 420c2091 authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds
Browse files

mm/gup: introduce pin_user_pages_locked() 

Patch series "mm/gup: introduce pin_user_pages_locked(), use it in frame_vector.c", v2.

This adds yet one more pin_user_pages*() variant, and uses that to
convert mm/frame_vector.c.

With this, along with maybe 20 or 30 other recent patches in various
trees, we are close to having the relevant gup call sites
converted--with the notable exception of the bio/block layer.

This patch (of 2):

Introduce pin_user_pages_locked(), which is nearly identical to
get_user_pages_locked() except that it sets FOLL_PIN and rejects
FOLL_GET.

As with other pairs of get_user_pages*() and pin_user_pages() API calls,
it's prudent to assert that FOLL_PIN is *not* set in the
get_user_pages*() call, so add that as part of this.

[jhubbard@nvidia.com: v2]
  Link: http://lkml.kernel.org/r/20200531234131.770697-2-jhubbard@nvidia.com



Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Acked-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Link: http://lkml.kernel.org/r/20200531234131.770697-1-jhubbard@nvidia.com
Link: http://lkml.kernel.org/r/20200527223243.884385-1-jhubbard@nvidia.com
Link: http://lkml.kernel.org/r/20200527223243.884385-2-jhubbard@nvidia.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a8f80f53

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -1706,6 +1706,8 @@ long pin_user_pages(unsigned long start, unsigned long nr_pages, 
		    struct vm_area_struct **vmas);

long get_user_pages_locked(unsigned long start, unsigned long nr_pages,

		    unsigned int gup_flags, struct page **pages, int *locked);

long pin_user_pages_locked(unsigned long start, unsigned long nr_pages,

		    unsigned int gup_flags, struct page **pages, int *locked);

long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,

		    struct page **pages, unsigned int gup_flags);

long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,

mm/gup.c

+35 −0
Original line number Diff line number Diff line
@@ -2035,6 +2035,12 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages, 
	 */

	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))

		return -EINVAL;

	/*

	 * FOLL_PIN must only be set internally by the pin_user_pages*() APIs,

	 * never directly by the caller, so enforce that:

	 */

	if (WARN_ON_ONCE(gup_flags & FOLL_PIN))

		return -EINVAL;



	return __get_user_pages_locked(current, current->mm, start, nr_pages,

				       pages, NULL, locked,
@@ -3058,3 +3064,32 @@ long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages, 
	return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);

}

EXPORT_SYMBOL(pin_user_pages_unlocked);



/*

 * pin_user_pages_locked() is the FOLL_PIN variant of get_user_pages_locked().

 * Behavior is the same, except that this one sets FOLL_PIN and rejects

 * FOLL_GET.

 */

long pin_user_pages_locked(unsigned long start, unsigned long nr_pages,

			   unsigned int gup_flags, struct page **pages,

			   int *locked)

{

	/*

	 * FIXME: Current FOLL_LONGTERM behavior is incompatible with

	 * FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on

	 * vmas.  As there are no users of this flag in this call we simply

	 * disallow this option for now.

	 */

	if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))

		return -EINVAL;



	/* FOLL_GET and FOLL_PIN are mutually exclusive. */

	if (WARN_ON_ONCE(gup_flags & FOLL_GET))

		return -EINVAL;



	gup_flags |= FOLL_PIN;

	return __get_user_pages_locked(current, current->mm, start, nr_pages,

				       pages, NULL, locked,

				       gup_flags | FOLL_TOUCH);

}

EXPORT_SYMBOL(pin_user_pages_locked);