diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index d29737018f04..b38b3a1c0307 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1909,6 +1909,16 @@ gen_sessionid(struct nfsd4_session *ses)
  */
 #define NFSD_MIN_HDR_SEQ_SZ  (24 + 12 + 44)
 
+static struct shrinker *nfsd_slot_shrinker;
+static DEFINE_SPINLOCK(nfsd_session_list_lock);
+static LIST_HEAD(nfsd_session_list);
+/* The sum of "target_slots-1" on every session.  The shrinker can push this
+ * down, though it can take a little while for the memory to actually
+ * be freed.  The "-1" is because we can never free slot 0 while the
+ * session is active.
+ */
+static atomic_t nfsd_total_target_slots = ATOMIC_INIT(0);
+
 static void
 free_session_slots(struct nfsd4_session *ses, int from)
 {
@@ -1930,8 +1940,11 @@ free_session_slots(struct nfsd4_session *ses, int from)
 		kfree(slot);
 	}
 	ses->se_fchannel.maxreqs = from;
-	if (ses->se_target_maxslots > from)
-		ses->se_target_maxslots = from;
+	if (ses->se_target_maxslots > from) {
+		int new_target = from ?: 1;
+		atomic_sub(ses->se_target_maxslots - new_target, &nfsd_total_target_slots);
+		ses->se_target_maxslots = new_target;
+	}
 }
 
 /**
@@ -1949,7 +1962,7 @@ free_session_slots(struct nfsd4_session *ses, int from)
  * Return value:
  *   The number of slots that the target was reduced by.
  */
-static int __maybe_unused
+static int
 reduce_session_slots(struct nfsd4_session *ses, int dec)
 {
 	struct nfsd_net *nn = net_generic(ses->se_client->net,
@@ -1962,6 +1975,7 @@ reduce_session_slots(struct nfsd4_session *ses, int dec)
 		return ret;
 	ret = min(dec, ses->se_target_maxslots-1);
 	ses->se_target_maxslots -= ret;
+	atomic_sub(ret, &nfsd_total_target_slots);
 	ses->se_slot_gen += 1;
 	if (ses->se_slot_gen == 0) {
 		int i;
@@ -2021,6 +2035,7 @@ static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs,
 	fattrs->maxreqs = i;
 	memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs));
 	new->se_target_maxslots = i;
+	atomic_add(i - 1, &nfsd_total_target_slots);
 	new->se_cb_slot_avail = ~0U;
 	new->se_cb_highest_slot = min(battrs->maxreqs - 1,
 				      NFSD_BC_SLOT_TABLE_SIZE - 1);
@@ -2145,6 +2160,36 @@ static void free_session(struct nfsd4_session *ses)
 	__free_session(ses);
 }
 
+static unsigned long
+nfsd_slot_count(struct shrinker *s, struct shrink_control *sc)
+{
+	unsigned long cnt = atomic_read(&nfsd_total_target_slots);
+
+	return cnt ? cnt : SHRINK_EMPTY;
+}
+
+static unsigned long
+nfsd_slot_scan(struct shrinker *s, struct shrink_control *sc)
+{
+	struct nfsd4_session *ses;
+	unsigned long scanned = 0;
+	unsigned long freed = 0;
+
+	spin_lock(&nfsd_session_list_lock);
+	list_for_each_entry(ses, &nfsd_session_list, se_all_sessions) {
+		freed += reduce_session_slots(ses, 1);
+		scanned += 1;
+		if (scanned >= sc->nr_to_scan) {
+			/* Move starting point for next scan */
+			list_move(&nfsd_session_list, &ses->se_all_sessions);
+			break;
+		}
+	}
+	spin_unlock(&nfsd_session_list_lock);
+	sc->nr_scanned = scanned;
+	return freed;
+}
+
 static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses)
 {
 	int idx;
@@ -2169,6 +2214,10 @@ static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, stru
 	list_add(&new->se_perclnt, &clp->cl_sessions);
 	spin_unlock(&clp->cl_lock);
 
+	spin_lock(&nfsd_session_list_lock);
+	list_add_tail(&new->se_all_sessions, &nfsd_session_list);
+	spin_unlock(&nfsd_session_list_lock);
+
 	{
 		struct sockaddr *sa = svc_addr(rqstp);
 		/*
@@ -2238,6 +2287,9 @@ unhash_session(struct nfsd4_session *ses)
 	spin_lock(&ses->se_client->cl_lock);
 	list_del(&ses->se_perclnt);
 	spin_unlock(&ses->se_client->cl_lock);
+	spin_lock(&nfsd_session_list_lock);
+	list_del(&ses->se_all_sessions);
+	spin_unlock(&nfsd_session_list_lock);
 }
 
 /* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */
@@ -2373,8 +2425,12 @@ unhash_client_locked(struct nfs4_client *clp)
 	}
 	list_del_init(&clp->cl_lru);
 	spin_lock(&clp->cl_lock);
-	list_for_each_entry(ses, &clp->cl_sessions, se_perclnt)
+	spin_lock(&nfsd_session_list_lock);
+	list_for_each_entry(ses, &clp->cl_sessions, se_perclnt) {
 		list_del_init(&ses->se_hash);
+		list_del_init(&ses->se_all_sessions);
+	}
+	spin_unlock(&nfsd_session_list_lock);
 	spin_unlock(&clp->cl_lock);
 }
 
@@ -4380,6 +4436,8 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 						GFP_NOWAIT))) {
 				s += 1;
 				session->se_fchannel.maxreqs = s;
+				atomic_add(s - session->se_target_maxslots,
+					   &nfsd_total_target_slots);
 				session->se_target_maxslots = s;
 			} else {
 				kfree(slot);
@@ -8770,7 +8828,6 @@ nfs4_state_start_net(struct net *net)
 }
 
 /* initialization to perform when the nfsd service is started: */
-
 int
 nfs4_state_start(void)
 {
@@ -8780,6 +8837,15 @@ nfs4_state_start(void)
 	if (ret)
 		return ret;
 
+	nfsd_slot_shrinker = shrinker_alloc(0, "nfsd-DRC-slot");
+	if (!nfsd_slot_shrinker) {
+		rhltable_destroy(&nfs4_file_rhltable);
+		return -ENOMEM;
+	}
+	nfsd_slot_shrinker->count_objects = nfsd_slot_count;
+	nfsd_slot_shrinker->scan_objects = nfsd_slot_scan;
+	shrinker_register(nfsd_slot_shrinker);
+
 	set_max_delegations();
 	return 0;
 }
@@ -8821,6 +8887,7 @@ void
 nfs4_state_shutdown(void)
 {
 	rhltable_destroy(&nfs4_file_rhltable);
+	shrinker_free(nfsd_slot_shrinker);
 }
 
 static void
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 2b0e6148a87a..b31a8523c8e5 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -325,6 +325,7 @@ struct nfsd4_session {
 	u32			se_cb_prog;
 	struct list_head	se_hash;	/* hash by sessionid */
 	struct list_head	se_perclnt;
+	struct list_head	se_all_sessions;/* global list of sessions */
 	struct nfs4_client	*se_client;
 	struct nfs4_sessionid	se_sessionid;
 	struct nfsd4_channel_attrs se_fchannel;