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authorJann Horn <jannh@google.com>2020-10-18 02:14:12 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-18 19:27:09 +0300
commitf3964599c22f70c37544c06b6b232c42746b940b (patch)
treef8e72270129ffb4247cddf38f58d0eba81435a46
parentfb8090b699c3e147e5bef8e0008edc3bddc33fad (diff)
downloadlinux-f3964599c22f70c37544c06b6b232c42746b940b.tar.xz
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 <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Acked-by: Michel Lespinasse <walken@google.com> Cc: "Eric W . Biederman" <ebiederm@xmission.com> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Sakari Ailus <sakari.ailus@linux.intel.com> Link: https://lkml.kernel.org/r/CAG48ez3SG6ngZLtasxJ6LABpOnqCz5-QHqb0B4k44TQ8F9n6+w@mail.gmail.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/gup_benchmark.c15
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;
}