This is a note to let you know that I've just added the patch titled
NFSD: add shrinker to reap courtesy clients on low memory condition
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nfsd-add-shrinker-to-reap-courtesy-clients-on-low-me.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b5e7c8b3931467061a7e9b035b4a1ba0a5029e80
Author: Dai Ngo <dai.ngo@xxxxxxxxxx>
Date: Wed Sep 14 08:54:26 2022 -0700
NFSD: add shrinker to reap courtesy clients on low memory condition
[ Upstream commit 7746b32f467b3813fb61faaab3258de35806a7ac ]
Add courtesy_client_reaper to react to low memory condition triggered
by the system memory shrinker.
The delayed_work for the courtesy_client_reaper is scheduled on
the shrinker's count callback using the laundry_wq.
The shrinker's scan callback is not used for expiring the courtesy
clients due to potential deadlocks.
Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
[ cel: adjusted to apply without e33c267ab70d ]
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 55c7006d6109a..8c854ba3285bb 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -194,6 +194,8 @@ struct nfsd_net {
int nfs4_max_clients;
atomic_t nfsd_courtesy_clients;
+ struct shrinker nfsd_client_shrinker;
+ struct delayed_work nfsd_shrinker_work;
};
/* Simple check to find out if a given net was properly initialized */
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9930c5f9440c7..d2468a408328d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4366,7 +4366,27 @@ nfsd4_init_slabs(void)
return -ENOMEM;
}
-void nfsd4_init_leases_net(struct nfsd_net *nn)
+static unsigned long
+nfsd_courtesy_client_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+ int cnt;
+ struct nfsd_net *nn = container_of(shrink,
+ struct nfsd_net, nfsd_client_shrinker);
+
+ cnt = atomic_read(&nn->nfsd_courtesy_clients);
+ if (cnt > 0)
+ mod_delayed_work(laundry_wq, &nn->nfsd_shrinker_work, 0);
+ return (unsigned long)cnt;
+}
+
+static unsigned long
+nfsd_courtesy_client_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+ return SHRINK_STOP;
+}
+
+int
+nfsd4_init_leases_net(struct nfsd_net *nn)
{
struct sysinfo si;
u64 max_clients;
@@ -4387,6 +4407,16 @@ void nfsd4_init_leases_net(struct nfsd_net *nn)
nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);
atomic_set(&nn->nfsd_courtesy_clients, 0);
+ nn->nfsd_client_shrinker.scan_objects = nfsd_courtesy_client_scan;
+ nn->nfsd_client_shrinker.count_objects = nfsd_courtesy_client_count;
+ nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;
+ return register_shrinker(&nn->nfsd_client_shrinker);
+}
+
+void
+nfsd4_leases_net_shutdown(struct nfsd_net *nn)
+{
+ unregister_shrinker(&nn->nfsd_client_shrinker);
}
static void init_nfs4_replay(struct nfs4_replay *rp)
@@ -5959,10 +5989,49 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
spin_unlock(&nn->client_lock);
}
+static void
+nfs4_get_courtesy_client_reaplist(struct nfsd_net *nn,
+ struct list_head *reaplist)
+{
+ unsigned int maxreap = 0, reapcnt = 0;
+ struct list_head *pos, *next;
+ struct nfs4_client *clp;
+
+ maxreap = NFSD_CLIENT_MAX_TRIM_PER_RUN;
+ INIT_LIST_HEAD(reaplist);
+
+ spin_lock(&nn->client_lock);
+ list_for_each_safe(pos, next, &nn->client_lru) {
+ clp = list_entry(pos, struct nfs4_client, cl_lru);
+ if (clp->cl_state == NFSD4_ACTIVE)
+ break;
+ if (reapcnt >= maxreap)
+ break;
+ if (!mark_client_expired_locked(clp)) {
+ list_add(&clp->cl_lru, reaplist);
+ reapcnt++;
+ }
+ }
+ spin_unlock(&nn->client_lock);
+}
+
+static void
+nfs4_process_client_reaplist(struct list_head *reaplist)
+{
+ struct list_head *pos, *next;
+ struct nfs4_client *clp;
+
+ list_for_each_safe(pos, next, reaplist) {
+ clp = list_entry(pos, struct nfs4_client, cl_lru);
+ trace_nfsd_clid_purged(&clp->cl_clientid);
+ list_del_init(&clp->cl_lru);
+ expire_client(clp);
+ }
+}
+
static time64_t
nfs4_laundromat(struct nfsd_net *nn)
{
- struct nfs4_client *clp;
struct nfs4_openowner *oo;
struct nfs4_delegation *dp;
struct nfs4_ol_stateid *stp;
@@ -5991,12 +6060,8 @@ nfs4_laundromat(struct nfsd_net *nn)
}
spin_unlock(&nn->s2s_cp_lock);
nfs4_get_client_reaplist(nn, &reaplist, <);
- list_for_each_safe(pos, next, &reaplist) {
- clp = list_entry(pos, struct nfs4_client, cl_lru);
- trace_nfsd_clid_purged(&clp->cl_clientid);
- list_del_init(&clp->cl_lru);
- expire_client(clp);
- }
+ nfs4_process_client_reaplist(&reaplist);
+
spin_lock(&state_lock);
list_for_each_safe(pos, next, &nn->del_recall_lru) {
dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
@@ -6079,6 +6144,18 @@ laundromat_main(struct work_struct *laundry)
queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);
}
+static void
+courtesy_client_reaper(struct work_struct *reaper)
+{
+ struct list_head reaplist;
+ struct delayed_work *dwork = to_delayed_work(reaper);
+ struct nfsd_net *nn = container_of(dwork, struct nfsd_net,
+ nfsd_shrinker_work);
+
+ nfs4_get_courtesy_client_reaplist(nn, &reaplist);
+ nfs4_process_client_reaplist(&reaplist);
+}
+
static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_stid *stp)
{
if (!fh_match(&fhp->fh_handle, &stp->sc_file->fi_fhandle))
@@ -7911,6 +7988,7 @@ static int nfs4_state_create_net(struct net *net)
INIT_LIST_HEAD(&nn->blocked_locks_lru);
INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main);
+ INIT_DELAYED_WORK(&nn->nfsd_shrinker_work, courtesy_client_reaper);
get_net(net);
return 0;
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 917fa1892fd2d..597a26ad4183f 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1481,11 +1481,12 @@ static __net_init int nfsd_init_net(struct net *net)
goto out_idmap_error;
nn->nfsd_versions = NULL;
nn->nfsd4_minorversions = NULL;
+ retval = nfsd4_init_leases_net(nn);
+ if (retval)
+ goto out_drc_error;
retval = nfsd_reply_cache_init(nn);
if (retval)
goto out_drc_error;
- nfsd4_init_leases_net(nn);
-
get_random_bytes(&nn->siphash_key, sizeof(nn->siphash_key));
seqlock_init(&nn->writeverf_lock);
@@ -1507,6 +1508,7 @@ static __net_exit void nfsd_exit_net(struct net *net)
nfsd_idmap_shutdown(net);
nfsd_export_shutdown(net);
nfsd_netns_free_versions(net_generic(net, nfsd_net_id));
+ nfsd4_leases_net_shutdown(nn);
}
static struct pernet_operations nfsd_net_ops = {
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 6ab4ad41ae84e..09726c5b9a317 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -505,7 +505,8 @@ extern void unregister_cld_notifier(void);
extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);
#endif
-extern void nfsd4_init_leases_net(struct nfsd_net *nn);
+extern int nfsd4_init_leases_net(struct nfsd_net *nn);
+extern void nfsd4_leases_net_shutdown(struct nfsd_net *nn);
#else /* CONFIG_NFSD_V4 */
static inline int nfsd4_is_junction(struct dentry *dentry)
@@ -513,7 +514,8 @@ static inline int nfsd4_is_junction(struct dentry *dentry)
return 0;
}
-static inline void nfsd4_init_leases_net(struct nfsd_net *nn) {};
+static inline int nfsd4_init_leases_net(struct nfsd_net *nn) { return 0; };
+static inline void nfsd4_leases_net_shutdown(struct nfsd_net *nn) {};
#define register_cld_notifier() 0
#define unregister_cld_notifier() do { } while(0)
