seq_open() stores its struct seq_file in file->private_data, thus it must
not be modified by user of seq_file.

Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@opteya.comSigned-off-by: NYann Droneaud <ydroneaud@opteya.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>