From: Ondřej Surý <ondrej@isc.org>
Date: Wed, 15 Jan 2025 09:36:33 +0000 (+0100)
Subject: Remove memory limit on ADB finds and fetches
X-Git-Tag: v9.21.5~42^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05faff6d5306de1e57b56f9ea44469bfb111e2e3;p=thirdparty%2Fbind9.git

Remove memory limit on ADB finds and fetches

Address Database (ADB) shares the memory for the short lived ADB
objects (finds, fetches, addrinfo) and the long lived ADB
objects (names, entries, namehooks).  This could lead to a situation
where the resolver-heavy load would force evict ADB objects from the
database to point where ADB is completely empty, leading to even more
resolver-heavy load.

Make the short lived ADB objects use the other memory context that we
already created for the hashmaps.  This makes the ADB overmem condition
to not be triggered by the ongoing resolver fetches.
---

diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index 23017a759ad..56b2edf52c7 100644
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@@ -1112,7 +1112,7 @@ static dns_adbfind_t *
 new_adbfind(dns_adb_t *adb, in_port_t port) {
 	dns_adbfind_t *find = NULL;
 
-	find = isc_mem_get(adb->mctx, sizeof(*find));
+	find = isc_mem_get(adb->hmctx, sizeof(*find));
 	*find = (dns_adbfind_t){
 		.port = port,
 		.result_v4 = ISC_R_UNEXPECTED,
@@ -1151,7 +1151,7 @@ free_adbfind(dns_adbfind_t **findp) {
 
 	isc_mutex_destroy(&find->lock);
 
-	isc_mem_put(adb->mctx, find, sizeof(*find));
+	isc_mem_put(adb->hmctx, find, sizeof(*find));
 	dns_adb_detach(&adb);
 }
 
@@ -1159,7 +1159,7 @@ static dns_adbfetch_t *
 new_adbfetch(dns_adb_t *adb) {
 	dns_adbfetch_t *fetch = NULL;
 
-	fetch = isc_mem_get(adb->mctx, sizeof(*fetch));
+	fetch = isc_mem_get(adb->hmctx, sizeof(*fetch));
 	*fetch = (dns_adbfetch_t){ 0 };
 	dns_rdataset_init(&fetch->rdataset);
 
@@ -1183,7 +1183,7 @@ free_adbfetch(dns_adb_t *adb, dns_adbfetch_t **fetchp) {
 		dns_rdataset_disassociate(&fetch->rdataset);
 	}
 
-	isc_mem_put(adb->mctx, fetch, sizeof(*fetch));
+	isc_mem_put(adb->hmctx, fetch, sizeof(*fetch));
 }
 
 /*
@@ -1194,7 +1194,7 @@ static dns_adbaddrinfo_t *
 new_adbaddrinfo(dns_adb_t *adb, dns_adbentry_t *entry, in_port_t port) {
 	dns_adbaddrinfo_t *ai = NULL;
 
-	ai = isc_mem_get(adb->mctx, sizeof(*ai));
+	ai = isc_mem_get(adb->hmctx, sizeof(*ai));
 	*ai = (dns_adbaddrinfo_t){
 		.srtt = atomic_load(&entry->srtt),
 		.flags = atomic_load(&entry->flags),
@@ -1227,7 +1227,7 @@ free_adbaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **ainfo) {
 	}
 	dns_adbentry_detach(&ai->entry);
 
-	isc_mem_put(adb->mctx, ai, sizeof(*ai));
+	isc_mem_put(adb->hmctx, ai, sizeof(*ai));
 }
 
 static bool
@@ -1863,7 +1863,7 @@ dns_adb_create(isc_mem_t *mem, dns_view_t *view, dns_adb_t **newadb) {
 	isc_mem_attach(mem, &adb->mctx);
 
 	isc_mem_create(&adb->hmctx);
-	isc_mem_setname(adb->hmctx, "ADB_hashmaps");
+	isc_mem_setname(adb->hmctx, "ADB_dynamic");
 
 	isc_hashmap_create(adb->hmctx, ADB_HASH_BITS, &adb->names);
 	isc_rwlock_init(&adb->names_lock);