From 239f4104dace964120d6d48868c9d6350154b61a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Wed, 15 Jan 2025 10:36:33 +0100
Subject: [PATCH] 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.

(cherry picked from commit 05faff6d5306de1e57b56f9ea44469bfb111e2e3)
---
 lib/dns/adb.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/dns/adb.c b/lib/dns/adb.c
index 8b6e153566..fb79d47ab1 100644
--- a/lib/dns/adb.c
+++ b/lib/dns/adb.c
@@ -718,21 +718,21 @@ grow_entries(isc_task_t *task, isc_event_t *ev) {
 
 cleanup:
 	if (newentries != NULL) {
-		isc_mem_put(adb->mctx, newentries, sizeof(*newentries) * n);
+		isc_mem_put(adb->hmctx, newentries, sizeof(*newentries) * n);
 	}
 	if (newdeadentries != NULL) {
-		isc_mem_put(adb->mctx, newdeadentries,
+		isc_mem_put(adb->hmctx, newdeadentries,
 			    sizeof(*newdeadentries) * n);
 	}
 	if (newentrylocks != NULL) {
-		isc_mem_put(adb->mctx, newentrylocks,
+		isc_mem_put(adb->hmctx, newentrylocks,
 			    sizeof(*newentrylocks) * n);
 	}
 	if (newentry_sd != NULL) {
-		isc_mem_put(adb->mctx, newentry_sd, sizeof(*newentry_sd) * n);
+		isc_mem_put(adb->hmctx, newentry_sd, sizeof(*newentry_sd) * n);
 	}
 	if (newentry_refcnt != NULL) {
-		isc_mem_put(adb->mctx, newentry_refcnt,
+		isc_mem_put(adb->hmctx, newentry_refcnt,
 			    sizeof(*newentry_refcnt) * n);
 	}
 done:
@@ -1929,7 +1929,7 @@ static dns_adbfind_t *
 new_adbfind(dns_adb_t *adb) {
 	dns_adbfind_t *h;
 
-	h = isc_mem_get(adb->mctx, sizeof(*h));
+	h = isc_mem_get(adb->hmctx, sizeof(*h));
 	isc_refcount_increment0(&adb->ahrefcnt);
 
 	/*
@@ -1965,7 +1965,7 @@ static dns_adbfetch_t *
 new_adbfetch(dns_adb_t *adb) {
 	dns_adbfetch_t *f;
 
-	f = isc_mem_get(adb->mctx, sizeof(*f));
+	f = isc_mem_get(adb->hmctx, sizeof(*f));
 
 	f->magic = 0;
 	f->fetch = NULL;
@@ -1991,7 +1991,7 @@ free_adbfetch(dns_adb_t *adb, dns_adbfetch_t **fetch) {
 		dns_rdataset_disassociate(&f->rdataset);
 	}
 
-	isc_mem_put(adb->mctx, f, sizeof(*f));
+	isc_mem_put(adb->hmctx, f, sizeof(*f));
 }
 
 static bool
@@ -2013,7 +2013,7 @@ free_adbfind(dns_adb_t *adb, dns_adbfind_t **findp) {
 	isc_mutex_destroy(&find->lock);
 
 	isc_refcount_decrement(&adb->ahrefcnt);
-	isc_mem_put(adb->mctx, find, sizeof(*find));
+	isc_mem_put(adb->hmctx, find, sizeof(*find));
 	return dec_adb_irefcnt(adb);
 }
 
@@ -2026,7 +2026,7 @@ static dns_adbaddrinfo_t *
 new_adbaddrinfo(dns_adb_t *adb, dns_adbentry_t *entry, in_port_t port) {
 	dns_adbaddrinfo_t *ai;
 
-	ai = isc_mem_get(adb->mctx, sizeof(*ai));
+	ai = isc_mem_get(adb->hmctx, sizeof(*ai));
 
 	ai->magic = DNS_ADBADDRINFO_MAGIC;
 	ai->sockaddr = entry->sockaddr;
@@ -2052,7 +2052,7 @@ free_adbaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **ainfo) {
 
 	ai->magic = 0;
 
-	isc_mem_put(adb->mctx, ai, sizeof(*ai));
+	isc_mem_put(adb->hmctx, ai, sizeof(*ai));
 }
 
 /*
@@ -2635,7 +2635,7 @@ dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *timermgr,
 	isc_mutex_init(&adb->namescntlock);
 
 	isc_mem_create(&adb->hmctx);
-	isc_mem_setname(adb->hmctx, "ADB_hashmaps");
+	isc_mem_setname(adb->hmctx, "ADB_dynamic");
 
 #define ALLOCENTRY(adb, el)                                                    \
 	do {                                                                   \