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damon dbgfs_mk_context() does not handle error from debugfs_create_dir() correctly. For example, if one tries to create a context with existing name, debugfs_create_dir() fails with -EEXIST, but dbgfs_mk_context() assumes the call is successful and adds another entry - which will cause failures when try to enable the monitor. Test case: echo "off" > /sys/kernel/debug/damon/monitor_on echo "abc" > /sys/kernel/debug/damon/mk_context echo "abc" > /sys/kernel/debug/damon/mk_context echo <pid> > /sys/kernel/debug/damon/target_ids echo "on" > /sys/kernel/debug/damon/monitor_on <<< fails to enable monitor Signed-off-by: Badari Pulavarty
badari.pulavarty@xxxxxxxxx --- --- orig/mm/damon/dbgfs.c 2022-08-05 13:35:54.416831666 -0400 +++ new/mm/damon/dbgfs.c 2022-08-05 13:44:25.121849930 -0400 @@ -721,6 +721,9 @@ static int dbgfs_mk_context(char *name) return -ENOENT; new_dir = debugfs_create_dir(name, root); + if (IS_ERR(new_dir)) { + return PTR_ERR(new_dir); + } dbgfs_dirs[dbgfs_nr_ctxs] = new_dir; new_ctx = dbgfs_new_ctx(); |
