| Message ID | 20200201034029.4063170-7-jhubbard@nvidia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/gup: track FOLL_PIN pages | expand |
On Fri, Jan 31, 2020 at 07:40:23PM -0800, John Hubbard wrote: > Internal to mm/gup.c, require that get_user_pages_fast() > and __get_user_pages_fast() identify themselves, by setting > FOLL_GET. This is required in order to be able to make decisions > based on "FOLL_PIN, or FOLL_GET, or both or neither are set", in > upcoming patches. > > Signed-off-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
On Fri 31-01-20 19:40:23, John Hubbard wrote: > Internal to mm/gup.c, require that get_user_pages_fast() > and __get_user_pages_fast() identify themselves, by setting > FOLL_GET. This is required in order to be able to make decisions > based on "FOLL_PIN, or FOLL_GET, or both or neither are set", in > upcoming patches. > > Signed-off-by: John Hubbard <jhubbard@nvidia.com> Looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > mm/gup.c | 19 +++++++++++++++++-- > 1 file changed, 17 insertions(+), 2 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 83473c2165f4..e899d2e6398c 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -2390,6 +2390,14 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > unsigned long len, end; > unsigned long flags; > int nr = 0; > + /* > + * Internally (within mm/gup.c), gup fast variants must set FOLL_GET, > + * because gup fast is always a "pin with a +1 page refcount" request. > + */ > + unsigned int gup_flags = FOLL_GET; > + > + if (write) > + gup_flags |= FOLL_WRITE; > > start = untagged_addr(start) & PAGE_MASK; > len = (unsigned long) nr_pages << PAGE_SHIFT; > @@ -2415,7 +2423,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, > if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && > gup_fast_permitted(start, end)) { > local_irq_save(flags); > - gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr); > + gup_pgd_range(start, end, gup_flags, pages, &nr); > local_irq_restore(flags); > } > > @@ -2454,7 +2462,7 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages, > int nr = 0, ret = 0; > > if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | > - FOLL_FORCE | FOLL_PIN))) > + FOLL_FORCE | FOLL_PIN | FOLL_GET))) > return -EINVAL; > > start = untagged_addr(start) & PAGE_MASK; > @@ -2521,6 +2529,13 @@ int get_user_pages_fast(unsigned long start, int nr_pages, > if (WARN_ON_ONCE(gup_flags & FOLL_PIN)) > return -EINVAL; > > + /* > + * The caller may or may not have explicitly set FOLL_GET; either way is > + * OK. However, internally (within mm/gup.c), gup fast variants must set > + * FOLL_GET, because gup fast is always a "pin with a +1 page refcount" > + * request. > + */ > + gup_flags |= FOLL_GET; > return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); > } > EXPORT_SYMBOL_GPL(get_user_pages_fast); > -- > 2.25.0 >
diff --git a/mm/gup.c b/mm/gup.c index 83473c2165f4..e899d2e6398c 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2390,6 +2390,14 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, unsigned long len, end; unsigned long flags; int nr = 0; + /* + * Internally (within mm/gup.c), gup fast variants must set FOLL_GET, + * because gup fast is always a "pin with a +1 page refcount" request. + */ + unsigned int gup_flags = FOLL_GET; + + if (write) + gup_flags |= FOLL_WRITE; start = untagged_addr(start) & PAGE_MASK; len = (unsigned long) nr_pages << PAGE_SHIFT; @@ -2415,7 +2423,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write, if (IS_ENABLED(CONFIG_HAVE_FAST_GUP) && gup_fast_permitted(start, end)) { local_irq_save(flags); - gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr); + gup_pgd_range(start, end, gup_flags, pages, &nr); local_irq_restore(flags); } @@ -2454,7 +2462,7 @@ static int internal_get_user_pages_fast(unsigned long start, int nr_pages, int nr = 0, ret = 0; if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | - FOLL_FORCE | FOLL_PIN))) + FOLL_FORCE | FOLL_PIN | FOLL_GET))) return -EINVAL; start = untagged_addr(start) & PAGE_MASK; @@ -2521,6 +2529,13 @@ int get_user_pages_fast(unsigned long start, int nr_pages, if (WARN_ON_ONCE(gup_flags & FOLL_PIN)) return -EINVAL; + /* + * The caller may or may not have explicitly set FOLL_GET; either way is + * OK. However, internally (within mm/gup.c), gup fast variants must set + * FOLL_GET, because gup fast is always a "pin with a +1 page refcount" + * request. + */ + gup_flags |= FOLL_GET; return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages); } EXPORT_SYMBOL_GPL(get_user_pages_fast);
Internal to mm/gup.c, require that get_user_pages_fast() and __get_user_pages_fast() identify themselves, by setting FOLL_GET. This is required in order to be able to make decisions based on "FOLL_PIN, or FOLL_GET, or both or neither are set", in upcoming patches. Signed-off-by: John Hubbard <jhubbard@nvidia.com> --- mm/gup.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-)