diff options
| author | Lorenzo Stoakes <lstoakes@gmail.com> | 2023-10-03 00:14:53 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-10-18 14:34:15 -0700 |
| commit | 9c4b21422507035f3e0a507a680c9b03c0bcc730 (patch) | |
| tree | 586a876d05bf8fe1306dccf437f5fec149aa95de /mm/gup.c | |
| parent | 0f20bba1688bdf3b32df0162511a67d4eda15790 (diff) | |
mm/gup: make failure to pin an error if FOLL_NOWAIT not specified
There really should be no circumstances under which a non-FOLL_NOWAIT GUP
operation fails to return any pages, so make this an error and warn on it.
To catch the trivial case, simply exit early if nr_pages == 0.
This brings __get_user_pages_locked() in line with the behaviour of its
nommu variant.
Link: https://lkml.kernel.org/r/2a42d96dd1e37163f90a0019a541163dafb7e4c3.1696288092.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 11 |
1 files changed, 11 insertions, 0 deletions
@@ -1471,6 +1471,9 @@ static __always_inline long __get_user_pages_locked(struct mm_struct *mm, long ret, pages_done; bool must_unlock = false; + if (!nr_pages) + return 0; + /* * The internal caller expects GUP to manage the lock internally and the * lock must be released when this returns. @@ -1595,6 +1598,14 @@ retry: mmap_read_unlock(mm); *locked = 0; } + + /* + * Failing to pin anything implies something has gone wrong (except when + * FOLL_NOWAIT is specified). + */ + if (WARN_ON_ONCE(pages_done == 0 && !(flags & FOLL_NOWAIT))) + return -EFAULT; + return pages_done; } |