diff --git a/tools/regression/fstest/tests/chown/00.t b/tools/regression/fstest/tests/chown/00.t
index 103ff597c4a6..eb1301093112 100644
--- a/tools/regression/fstest/tests/chown/00.t
+++ b/tools/regression/fstest/tests/chown/00.t
@@ -238,6 +238,7 @@ ctime1=`${fstest} stat ${n0} ctime`
 sleep 1
 expect 0 -- chown ${n0} -1 -1
 ctime2=`${fstest} stat ${n0} ctime`
+todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 test_check $ctime1 -eq $ctime2
 expect 0 unlink ${n0}
 # 158
@@ -246,6 +247,7 @@ ctime1=`${fstest} stat ${n0} ctime`
 sleep 1
 expect 0 -- chown ${n0} -1 -1
 ctime2=`${fstest} stat ${n0} ctime`
+todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 test_check $ctime1 -eq $ctime2
 expect 0 rmdir ${n0}
 # 162
@@ -254,6 +256,7 @@ ctime1=`${fstest} stat ${n0} ctime`
 sleep 1
 expect 0 -- chown ${n0} -1 -1
 ctime2=`${fstest} stat ${n0} ctime`
+todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 test_check $ctime1 -eq $ctime2
 expect 0 unlink ${n0}
 # 166
@@ -262,6 +265,7 @@ ctime1=`${fstest} lstat ${n0} ctime`
 sleep 1
 expect 0 -- lchown ${n0} -1 -1
 ctime2=`${fstest} lstat ${n0} ctime`
+todo Linux "According to POSIX: If both owner and group are -1, the times need not be updated."
 test_check $ctime1 -eq $ctime2
 expect 0 unlink ${n0}
 
diff --git a/tools/regression/fstest/tests/rename/21.t b/tools/regression/fstest/tests/rename/21.t
index a9445c786cbf..7fa2f9c9e36b 100644
--- a/tools/regression/fstest/tests/rename/21.t
+++ b/tools/regression/fstest/tests/rename/21.t
@@ -37,9 +37,12 @@ expect ENOENT rmdir ${n3}/${n1}
 # Check that write permission on containing directory (${n2}) is enough
 # to move file (${n0}) from that directory.
 expect 0 create ${n2}/${n0} 0755
+todo Linux "According to POSIX, write access to ${n2}/${n0} and (if exists) ${n3}/${n1} may be required if ${n0} and (if exists) ${n1} are directories, not regular files."
 expect 0 -u 65534 -g 65534 rename ${n2}/${n0} ${n3}/${n1}
 
+todo Linux "According to POSIX, write access to ${n2}/${n0} and (if exists) ${n3}/${n1} may be required if ${n0} and (if exists) ${n1} are directories, not regular files."
 expect 0 unlink ${n3}/${n1}
+todo Linux "According to POSIX, write access to ${n2}/${n0} and (if exists) ${n3}/${n1} may be required if ${n0} and (if exists) ${n1} are directories, not regular files."
 expect ENOENT unlink ${n2}/${n0}
 
 expect 0 rmdir ${n3}
diff --git a/tools/regression/fstest/tests/unlink/08.t b/tools/regression/fstest/tests/unlink/08.t
index e872a1977314..ac81bd66876e 100644
--- a/tools/regression/fstest/tests/unlink/08.t
+++ b/tools/regression/fstest/tests/unlink/08.t
@@ -11,5 +11,6 @@ echo "1..3"
 n0=`namegen`
 
 expect 0 mkdir ${n0} 0755
+todo Linux "According to POSIX: EPERM - The file named by path is a directory, and either the calling process does not have appropriate privileges, or the implementation prohibits using unlink() on directories."
 expect "0|EPERM" unlink ${n0}
 expect "0|ENOENT" rmdir ${n0}