1 files changed, 17 insertions, 1 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 79b5da2acbe1..35e7d08fe629 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -649,7 +649,23 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
         if (!of)
                 goto err_out;
 
-        mutex_init(&of->mutex);
+        /*
+         * The following is done to give a different lockdep key to
+         * @of->mutex for files which implement mmap.  This is a rather
+         * crude way to avoid false positive lockdep warning around
+         * mm->mmap_sem - mmap nests @of->mutex under mm->mmap_sem and
+         * reading /sys/block/sda/trace/act_mask grabs sr_mutex, under
+         * which mm->mmap_sem nests, while holding @of->mutex.  As each
+         * open file has a separate mutex, it's okay as long as those don't
+         * happen on the same file.  At this point, we can't easily give
+         * each file a separate locking class.  Let's differentiate on
+         * whether the file is bin or not for now.
+         */
+        if (sysfs_is_bin(attr_sd))
+                mutex_init(&of->mutex);
+        else
+                mutex_init(&of->mutex);
+
         of->sd = attr_sd;
         of->file = file;