diff options
| author | Jann Horn <[email protected]> | 2020-10-17 16:14:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2020-10-18 09:27:09 -0700 |
| commit | f3964599c22f70c37544c06b6b232c42746b940b (patch) | |
| tree | f8e72270129ffb4247cddf38f58d0eba81435a46 | |
| parent | fb8090b699c3e147e5bef8e0008edc3bddc33fad (diff) | |
mm/gup_benchmark: take the mmap lock around GUP
To be safe against concurrent changes to the VMA tree, we must take the
mmap lock around GUP operations (excluding the GUP-fast family of
operations, which will take the mmap lock by themselves if necessary).
This code is only for testing, and it's only reachable by root through
debugfs, so this doesn't really have any impact; however, if we want to
add lockdep asserts into the GUP path, we need to have clean locking here.
Signed-off-by: Jann Horn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Acked-by: Michel Lespinasse <[email protected]>
Cc: "Eric W . Biederman" <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Sakari Ailus <[email protected]>
Link: https://lkml.kernel.org/r/CAG48ez3SG6ngZLtasxJ6LABpOnqCz5-QHqb0B4k44TQ8F9n6+w@mail.gmail.com
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/gup_benchmark.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c index 464cae1fa3ea..8b3e5b5cd8fa 100644 --- a/mm/gup_benchmark.c +++ b/mm/gup_benchmark.c @@ -72,6 +72,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd, int nr; struct page **pages; int ret = 0; + bool needs_mmap_lock = + cmd != GUP_FAST_BENCHMARK && cmd != PIN_FAST_BENCHMARK; if (gup->size > ULONG_MAX) return -EINVAL; @@ -81,6 +83,11 @@ static int __gup_benchmark_ioctl(unsigned int cmd, if (!pages) return -ENOMEM; + if (needs_mmap_lock && mmap_read_lock_killable(current->mm)) { + ret = -EINTR; + goto free_pages; + } + i = 0; nr = gup->nr_pages_per_call; start_time = ktime_get(); @@ -120,9 +127,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd, pages + i, NULL); break; default: - kvfree(pages); ret = -EINVAL; - goto out; + goto unlock; } if (nr <= 0) @@ -150,8 +156,11 @@ static int __gup_benchmark_ioctl(unsigned int cmd, end_time = ktime_get(); gup->put_delta_usec = ktime_us_delta(end_time, start_time); +unlock: + if (needs_mmap_lock) + mmap_read_unlock(current->mm); +free_pages: kvfree(pages); -out: return ret; } |