diff --git a/mdb.c b/mdb.c
index a07306c8..0c7397c2 100644
--- a/mdb.c
+++ b/mdb.c
@@ -4184,8 +4184,8 @@ mdb_env_map(MDB_env *env, void *addr)
 		if (ftruncate(env->me_fd, env->me_mapsize) < 0)
 			return errno;
 	}
-	env->me_map = mmap(addr, env->me_mapsize, prot, MAP_SHARED,
-		env->me_fd, 0);
+
+	env->me_map = mmap(addr, env->me_mapsize, prot, MAP_SHARED, env->me_fd, 0);
 	if (env->me_map == MAP_FAILED) {
 		env->me_map = NULL;
 		return errno;
@@ -4195,11 +4195,9 @@ mdb_env_map(MDB_env *env, void *addr)
 		/* Turn off readahead. It's harmful when the DB is larger than RAM. */
 #ifdef MADV_RANDOM
 		madvise(env->me_map, env->me_mapsize, MADV_RANDOM);
-#else
-#ifdef POSIX_MADV_RANDOM
+#elif defined(POSIX_MADV_RANDOM)
 		posix_madvise(env->me_map, env->me_mapsize, POSIX_MADV_RANDOM);
-#endif /* POSIX_MADV_RANDOM */
-#endif /* MADV_RANDOM */
+#endif /* MADV_RANDOM & POSIX_MADV_RANDOM */
 	}
 
 	/* Can happen because the address argument to mmap() is just a
@@ -4207,8 +4205,10 @@ mdb_env_map(MDB_env *env, void *addr)
 	 * The MAP_FIXED flag would prevent that, but then mmap could
 	 * instead unmap existing pages to make room for the new map.
 	 */
-	if (addr && env->me_map != addr)
+	if (addr && env->me_map != addr) {
+		errno = 0;	/* LY: clean errno as a hit for this case */
 		return EBUSY;	/* TODO: Make a new MDB_* error code? */
+	}
 
 	/* Lock meta pages to avoid unexpected write,
 	 *  before the data pages would be synchronized. */
diff --git a/mtest0.c b/mtest0.c
index 4fe9a15a..0fdd0898 100644
--- a/mtest0.c
+++ b/mtest0.c
@@ -14,6 +14,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -21,6 +24,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -34,6 +41,8 @@ int main(int argc,char * argv[])
 	int count;
 	int *values;
 	char sval[32] = "";
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -47,7 +56,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_create(&env));
 	E(mdb_env_set_maxreaders(env, 1));
 	E(mdb_env_set_mapsize(env, 10485760));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP /*|MDB_NOSYNC*/, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	E(mdb_dbi_open(txn, NULL, 0, &dbi));
diff --git a/mtest1.c b/mtest1.c
index eb26ffd2..e531cacb 100644
--- a/mtest1.c
+++ b/mtest1.c
@@ -23,6 +23,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -30,6 +33,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -42,6 +49,8 @@ int main(int argc,char * argv[])
 	int count;
 	int *values;
 	char sval[32] = "";
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -53,11 +62,25 @@ int main(int argc,char * argv[])
 	}
 
 	E(mdb_env_create(&env));
-
 	E(mdb_env_set_maxreaders(env, 1));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	/* LY: especially here we always needs MDB_NOSYNC
+	 * for testing mdb_env_close_ex() and "redo-to-steady" on open. */
+	env_oflags |= MDB_NOSYNC;
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id1", MDB_CREATE, &dbi) == MDB_SUCCESS)
@@ -144,7 +167,7 @@ int main(int argc,char * argv[])
 	mdb_env_close_ex(env, 1);
 	E(mdb_env_create(&env));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	printf("check-preset-c.cursor-next\n");
 	E(mdb_env_stat(env, &mst));
diff --git a/mtest2.c b/mtest2.c
index e1ab1ca8..5650af3f 100644
--- a/mtest2.c
+++ b/mtest2.c
@@ -17,6 +17,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -36,6 +43,8 @@ int main(int argc,char * argv[])
 	int count;
 	int *values;
 	char sval[32] = "";
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -50,7 +59,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_set_maxreaders(env, 1));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id2", MDB_CREATE, &dbi) == MDB_SUCCESS)
diff --git a/mtest3.c b/mtest3.c
index 6e3b9e02..bbb0906e 100644
--- a/mtest3.c
+++ b/mtest3.c
@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -37,6 +44,8 @@ int main(int argc,char * argv[])
 	int *values;
 	char sval[32];
 	char kval[sizeof(int)];
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -52,7 +61,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id3", MDB_CREATE, &dbi) == MDB_SUCCESS)
diff --git a/mtest4.c b/mtest4.c
index 22f4af85..c24a7034 100644
--- a/mtest4.c
+++ b/mtest4.c
@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -37,6 +44,8 @@ int main(int argc,char * argv[])
 	int *values;
 	char sval[8];
 	char kval[sizeof(int)];
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	memset(sval, 0, sizeof(sval));
 
@@ -50,7 +59,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id4", MDB_CREATE, &dbi) == MDB_SUCCESS)
diff --git a/mtest5.c b/mtest5.c
index 11913da8..877911ed 100644
--- a/mtest5.c
+++ b/mtest5.c
@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 int main(int argc,char * argv[])
 {
 	int i = 0, j = 0, rc;
@@ -37,6 +44,8 @@ int main(int argc,char * argv[])
 	int *values;
 	char sval[32];
 	char kval[sizeof(int)];
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
@@ -52,7 +61,19 @@ int main(int argc,char * argv[])
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id5", MDB_CREATE, &dbi) == MDB_SUCCESS)
diff --git a/mtest6.c b/mtest6.c
index a1255bca..51ac39e3 100644
--- a/mtest6.c
+++ b/mtest6.c
@@ -17,6 +17,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/stat.h>
 #include "lmdb.h"
 
 #define E(expr) CHECK((rc = (expr)) == MDB_SUCCESS, #expr)
@@ -24,6 +27,10 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
+
 char dkbuf[1024];
 
 int main(int argc,char * argv[])
@@ -37,13 +44,27 @@ int main(int argc,char * argv[])
 	MDB_cursor *cursor;
 	long kval;
 	char *sval;
+	int env_oflags;
+	struct stat db_stat, exe_stat;
 
 	srand(time(NULL));
 
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, 10485760));
 	E(mdb_env_set_maxdbs(env, 4));
-	E(mdb_env_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664));
+
+	E(stat("/proc/self/exe", &exe_stat)?errno:0);
+	E(stat(DBPATH "/.", &db_stat)?errno:0);
+	env_oflags = MDB_FIXEDMAP | MDB_NOSYNC;
+	if (major(db_stat.st_dev) != major(exe_stat.st_dev)) {
+		/* LY: Assume running inside a CI-environment:
+		 *  1) don't use FIXEDMAP to avoid EBUSY in case collision,
+		 *     which could be inspired by address space randomisation feature.
+		 *  2) drop MDB_NOSYNC expecting that DBPATH is at a tmpfs or some dedicated storage.
+		 */
+		env_oflags = 0;
+	}
+	E(mdb_env_open(env, DBPATH, env_oflags, 0664));
 
 	E(mdb_txn_begin(env, NULL, 0, &txn));
 	if (mdb_dbi_open(txn, "id6", MDB_CREATE, &dbi) == MDB_SUCCESS)
diff --git a/wbench.c b/wbench.c
index 50a7aca3..1b5f3794 100644
--- a/wbench.c
+++ b/wbench.c
@@ -25,6 +25,7 @@
 #include <sys/types.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <errno.h>
 
 #include "lmdb.h"
 
@@ -33,7 +34,9 @@
 #define CHECK(test, msg) ((test) ? (void)0 : ((void)fprintf(stderr, \
 	"%s:%d: %s: %s\n", __FILE__, __LINE__, msg, mdb_strerror(rc)), abort()))
 
-#define DBPATH "./testdb"
+#ifndef DBPATH
+#	define DBPATH "./testdb"
+#endif
 
 struct t0 {
 	struct rusage ru;
@@ -124,7 +127,7 @@ static void wbench(int flags, int mb, int count, int salt)
 
 	E(mdb_env_create(&env));
 	E(mdb_env_set_mapsize(env, (1ull << 20) * mb));
-	E(mdb_env_open(env, "./testdb", flags, 0664));
+	E(mdb_env_open(env, DBPATH, flags, 0664));
 
 	key.mv_size = sizeof(key_value);
 	key.mv_data = &key_value;