From ad7b26ecdc386b7d660aac53744aeedf2b4ef2b5 Mon Sep 17 00:00:00 2001
From: Edward Tomasz Napierala <trasz@FreeBSD.org>
Date: Thu, 29 Oct 2020 15:44:44 +0000
Subject: [PATCH] Make linprocfs(4) print a warning when there's not enough
 room to fill /proc/self/maps.

Submitted by:	dchagin (earlier version)
Reviewed by:	emaste (earlier version)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20576
---
 sys/compat/linprocfs/linprocfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index b346fe84f7c..515253cfdd9 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -1252,6 +1252,10 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 		    *name ? "     " : " ",
 		    name
 		    );
+		if (error == -1) {
+			linux_msg(td, "cannot fill /proc/self/maps; "
+			    "consider bumping PFS_MAXBUFSIZ");
+		}
 		if (freename)
 			free(freename, M_TEMP);
 		vm_map_lock_read(map);