From: John Hubbard <jhubbard@xxxxxxxxxx> Subject: 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@xxxxxxxxxx: v2] Link: http://lkml.kernel.org/r/20200531234131.770697-2-jhubbard@xxxxxxxxxx Link: http://lkml.kernel.org/r/20200531234131.770697-1-jhubbard@xxxxxxxxxx Link: http://lkml.kernel.org/r/20200527223243.884385-1-jhubbard@xxxxxxxxxx Link: http://lkml.kernel.org/r/20200527223243.884385-2-jhubbard@xxxxxxxxxx Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx> Acked-by: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx> Cc: Daniel Vetter <daniel@xxxxxxxx> Cc: Jérôme Glisse <jglisse@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 2 ++ mm/gup.c | 36 ++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) --- a/include/linux/mm.h~mm-gup-introduce-pin_user_pages_locked +++ a/include/linux/mm.h @@ -1706,6 +1706,8 @@ long pin_user_pages(unsigned long start, 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, --- a/mm/gup.c~mm-gup-introduce-pin_user_pages_locked +++ a/mm/gup.c @@ -2035,6 +2035,12 @@ long get_user_pages_locked(unsigned long */ 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 +3064,33 @@ long pin_user_pages_unlocked(unsigned lo 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); + _
