commit 572b7aa2460ff0561ec3be09b850e5ded2164353
Author: Michael Matz <matz@suse.de>
Date:   Mon Apr 27 14:36:14 2026 +0200

    Give hint when ptrace is prevented by yama
    
    like for SElinux yama can be configured to prevent attaching
    to processes by PID, so give a hint about that as well.

diff --git a/sysdeps/linux-gnu/trace.c b/sysdeps/linux-gnu/trace.c
index 12c8747..3d87605 100644
--- a/sysdeps/linux-gnu/trace.c
+++ b/sysdeps/linux-gnu/trace.c
@@ -60,12 +60,13 @@
 void
 trace_fail_warning(pid_t pid)
 {
-	/* This was adapted from GDB.  */
-#ifdef HAVE_LIBSELINUX
 	static int checked = 0;
+	FILE *fp;
 	if (checked)
 		return;
 	checked = 1;
+	/* This was adapted from GDB.  */
+#ifdef HAVE_LIBSELINUX
 
 	/* -1 is returned for errors, 0 if it has no effect, 1 if
 	 * PTRACE_ATTACH is forbidden.  */
@@ -75,6 +76,15 @@ trace_fail_warning(pid_t pid)
 "tracing other processes.  You can disable this process attach protection by\n"
 "issuing 'setsebool deny_ptrace=0' in the superuser context.\n");
 #endif /* HAVE_LIBSELINUX */
+	fp = fopen("/proc/sys/kernel/yama/ptrace_scope", "r");
+	if (fp) {
+		int yamaval = 0;
+		if(fscanf(fp, "%d", &yamaval) == 1 && yamaval > 0)
+			fprintf(stderr,
+"The sysctl(8) setting kernel.yama.ptrace_scope is '%d', which prevents\n"
+"attaching to already running processes by pid.\n", yamaval);
+		fclose(fp);
+	}
 }
 
 void