fix maxmemory config warning

the warning condition was if usage > limit (saying it'll cause eviction
or oom), but in fact the eviction and oom depends on used minus slave
buffers.

other than fixing the condition, i add info about the current usage and
limit, which may be useful when looking at the log.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/config.c b/src/config.c
index b19e78f74..173a90909 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1995,8 +1995,9 @@ static int updateMaxmemory(long long val, long long prev, char **err) {
     UNUSED(prev);
     UNUSED(err);
     if (val) {
-        if ((unsigned long long)val < zmalloc_used_memory()) {
-            serverLog(LL_WARNING,"WARNING: the new maxmemory value set via CONFIG SET is smaller than the current memory usage. This will result in key eviction and/or the inability to accept new write commands depending on the maxmemory-policy.");
+        size_t used = zmalloc_used_memory()-freeMemoryGetNotCountedMemory();
+        if ((unsigned long long)val < used) {
+            serverLog(LL_WARNING,"WARNING: the new maxmemory value set via CONFIG SET (%llu) is smaller than the current memory usage (%zu). This will result in key eviction and/or the inability to accept new write commands depending on the maxmemory-policy.", server.maxmemory, used);
         }
         freeMemoryIfNeededAndSafe();
     }