2 files changed, 19 insertions, 0 deletions

diff --git a/share/man/man9/malloc.9 b/share/man/man9/malloc.9
index ff07220e1bcc..601389731719 100644
--- a/share/man/man9/malloc.9
+++ b/share/man/man9/malloc.9
@@ -159,6 +159,17 @@ is defined to be 0, meaning that blocking operation is the default.
 Also note that
 .Dv M_NOWAIT
 is required when running in an interrupt context.
+.Pp
+Programmers should be careful not to confuse
+.Dv M_NOWAIT ,
+the
+.Fn malloc
+flag, with
+.Dv M_DONTWAIT ,
+an
+.Xr mbuf 9
+allocation flag, which is not a valid argument to
+.Fn malloc .
 .It Dv M_WAITOK
 Indicates that it is Ok to wait for resources.  It is unconveniently
 defined as 0 so care should be taken never to compare against this value
diff --git a/share/man/man9/mbuf.9 b/share/man/man9/mbuf.9
index 647228907fbd..b10e6ea73a7c 100644
--- a/share/man/man9/mbuf.9
+++ b/share/man/man9/mbuf.9
@@ -295,6 +295,14 @@ number of ticks.
 A number of other mbuf-related
 functions and macros have the same argument because they may
 at some point need to allocate new mbufs.
+.Pp
+Programmers should be careful not to confuse the mbuf allocation flag
+.Dv M_DONTWAIT
+with the
+.Xr malloc 9
+allocation flag,
+.Dv M_NOWAIT .
+They are not the same.
 .It Fn MGETHDR mbuf how type
 Allocate an mbuf and initialize it to contain a packet header
 and internal data.