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-rw-r--r--fs/sysfs/file.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 79b5da2acbe..35e7d08fe62 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;