FAILED: patch "[PATCH] nfsd: dedup nfs4_client_to_reclaim inserts" failed to apply to 6.12-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 3 – Sep 5

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2026-09-03 13:39 UTC #0 lore raw

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 9b57793863f69c608691c98e57c2f9be2db9dfed
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090325-triage-suitor-da06@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9b57793863f69c608691c98e57c2f9be2db9dfed Mon Sep 17 00:00:00 2001
From: Jeff Layton <[email protected]>
Date: Sat, 30 May 2026 09:19:20 -0400
Subject: [PATCH] nfsd: dedup nfs4_client_to_reclaim inserts

nfs4_client_to_reclaim() unconditionally allocates a new nfs4_client_reclaim, prepends it to reclaim_str_hashtbl[], and bumps reclaim_str_hashtbl_size with no check for an existing entry for the same client name. After a reboot with a populated recovery directory that inflates the counter by one for every client that reclaims:

    boot:    load_recdir()
               nfs4_client_to_reclaim(name)   /* entry #1, size++ */

    grace:   RECLAIM_COMPLETE
               __nfsd4_create_reclaim_record_grace()
                 nfs4_client_to_reclaim(name) /* entry #2, size++ */

inc_reclaim_complete() ends the grace period early only when

    atomic_inc_return(&nn->nr_reclaim_complete) ==
        nn->reclaim_str_hashtbl_size

With reclaim_str_hashtbl_size at 2N and nr_reclaim_complete capped at N, the equality never holds and the fast end-of-grace path is dead. The grace period always runs out the full 90-second laundromat timer, and the shadow entry left in the hash table carries a dangling cr_clp for any reader that walks it.

Fix nfs4_client_to_reclaim() to look the name up with nfsd4_find_reclaim_client() first and, on a hit, fold the new princhash into the existing record (if it lacks one) and return that record without allocating or touching reclaim_str_hashtbl_size. On kmemdup() failure during the fold-in, return NULL so __cld_pipe_inprogress_downcall() surfaces -EFAULT to nfsdcld, matching the miss-path contract.

Add an rw_semaphore (reclaim_str_hashtbl_lock) to struct nfsd_net that serialises all access to reclaim_str_hashtbl[] and reclaim_str_hashtbl_size. Writers (nfs4_client_to_reclaim, nfs4_remove_reclaim_record callers) hold the write side; readers (nfsd4_cld_check*, inc_reclaim_complete, clients_still_reclaiming, nfs4_has_reclaimed_state, nfsd4_check_legacy_client) hold the read side. All call sites are in sleepable context, and none is a hot path, so the rwsem cost is negligible.

Reported-by Chris Mason <[email protected]>

Fixes 362063a595be ("nfsd: keep a tally of RECLAIM_COMPLETE operations when using nfsdcld")

Cc [email protected]

Assisted-by kres:claude-opus-4-7

Signed-off-by Jeff Layton <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Chuck Lever <[email protected]>

fs/nfsd/netns.h +5 -1

index 37dfecb9d49d..f6b8b340bf8e 100644
@@ -93,6 +93,7 @@ struct nfsd_net {
 	 */
 	struct list_head *reclaim_str_hashtbl;
 	int reclaim_str_hashtbl_size;
+	struct rw_semaphore reclaim_str_hashtbl_lock;
 	struct list_head *conf_id_hashtbl;
 	struct rb_root conf_name_tree;
 	struct list_head *unconf_id_hashtbl;

@@ -105,7 +106,10 @@ struct nfsd_net {
 	 * close_lru holds (open) stateowner queue ordered by nfs4_stateowner.so_time
 	 * for last close replay.
 	 *
-	 * All of the above fields are protected by the client_mutex.
+	 * reclaim_str_hashtbl[], reclaim_str_hashtbl_size are protected by
+	 * reclaim_str_hashtbl_lock.
+	 *
+	 * All of the remaining fields are protected by the client_lock.
 	 */
 	struct list_head client_lru;
 	struct list_head close_lru;

fs/nfsd/nfs4recover.c +29 -7

index c841da585142..d513971fb119 100644
@@ -285,10 +285,12 @@ __nfsd4_remove_reclaim_record_grace(const char *dname, int len,
 		return;
 	}
 	name.len = len;
+	down_write(&nn->reclaim_str_hashtbl_lock);
 	crp = nfsd4_find_reclaim_client(name, nn);
-	kfree(name.data);
 	if (crp)
 		nfs4_remove_reclaim_record(crp, nn);
+	up_write(&nn->reclaim_str_hashtbl_lock);
+	kfree(name.data);
 }
 
 static void

@@ -484,6 +486,7 @@ nfs4_legacy_state_init(struct net *net)
 	for (i = 0; i < CLIENT_HASH_SIZE; i++)
 		INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]);
 	nn->reclaim_str_hashtbl_size = 0;
+	init_rwsem(&nn->reclaim_str_hashtbl_lock);
 
 	return 0;
 }

@@ -598,13 +601,16 @@ nfsd4_check_legacy_client(struct nfs4_client *clp)
 		goto out_enoent;
 	}
 	name.len = HEXDIR_LEN;
+	down_read(&nn->reclaim_str_hashtbl_lock);
 	crp = nfsd4_find_reclaim_client(name, nn);
-	kfree(name.data);
 	if (crp) {
 		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
 		crp->cr_clp = clp;
-		return 0;
 	}
+	up_read(&nn->reclaim_str_hashtbl_lock);
+	kfree(name.data);
+	if (crp)
+		return 0;
 
 out_enoent:
 	return -ENOENT;

@@ -1176,6 +1182,7 @@ nfsd4_cld_check(struct nfs4_client *clp)
 		return 0;
 
 	/* look for it in the reclaim hashtable otherwise */
+	down_read(&nn->reclaim_str_hashtbl_lock);
 	crp = nfsd4_find_reclaim_client(clp->cl_name, nn);
 	if (crp)
 		goto found;

@@ -1191,6 +1198,7 @@ nfsd4_cld_check(struct nfs4_client *clp)
 		if (!name.data) {
 			dprintk("%s: failed to allocate memory for name.data!\n",
 				__func__);
+			up_read(&nn->reclaim_str_hashtbl_lock);
 			return -ENOENT;
 		}
 		name.len = HEXDIR_LEN;

@@ -1201,9 +1209,11 @@ nfsd4_cld_check(struct nfs4_client *clp)
 
 	}
 #endif
+	up_read(&nn->reclaim_str_hashtbl_lock);
 	return -ENOENT;
 found:
 	crp->cr_clp = clp;
+	up_read(&nn->reclaim_str_hashtbl_lock);
 	return 0;
 }

@@ -1215,6 +1225,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp)
 	struct cld_net *cn = nn->cld_net;
 #endif
 	struct nfs4_client_reclaim *crp;
+	unsigned int princhashlen;
 	char *principal = NULL;
 
 	/* did we already find that this client is stable? */

@@ -1222,6 +1233,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp)
 		return 0;
 
 	/* look for it in the reclaim hashtable otherwise */
+	down_read(&nn->reclaim_str_hashtbl_lock);
 	crp = nfsd4_find_reclaim_client(clp->cl_name, nn);
 	if (crp)
 		goto found;

@@ -1237,6 +1249,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp)
 		if (!name.data) {
 			dprintk("%s: failed to allocate memory for name.data\n",
 					__func__);
+			up_read(&nn->reclaim_str_hashtbl_lock);
 			return -ENOENT;
 		}
 		name.len = HEXDIR_LEN;

@@ -1247,23 +1260,31 @@ nfsd4_cld_check_v2(struct nfs4_client *clp)
 
 	}
 #endif
+	up_read(&nn->reclaim_str_hashtbl_lock);
 	return -ENOENT;
 found:
-	if (crp->cr_princhash.len) {
+	princhashlen = crp->cr_princhash.len;
+	if (princhashlen) {
 		u8 digest[SHA256_DIGEST_SIZE];
+		u8 *pdata;
 
 		if (clp->cl_cred.cr_raw_principal)
 			principal = clp->cl_cred.cr_raw_principal;
 		else if (clp->cl_cred.cr_principal)
 			principal = clp->cl_cred.cr_principal;
-		if (principal == NULL)
+		if (principal == NULL) {
+			up_read(&nn->reclaim_str_hashtbl_lock);
 			return -ENOENT;
+		}
 		sha256(principal, strlen(principal), digest);
-		if (memcmp(crp->cr_princhash.data, digest,
-				crp->cr_princhash.len))
+		pdata = crp->cr_princhash.data;
+		if (memcmp(pdata, digest, princhashlen)) {
+			up_read(&nn->reclaim_str_hashtbl_lock);
 			return -ENOENT;
+		}
 	}
 	crp->cr_clp = clp;
+	up_read(&nn->reclaim_str_hashtbl_lock);
 	return 0;
 }

@@ -1362,6 +1383,7 @@ nfs4_cld_state_init(struct net *net)
 	for (i = 0; i < CLIENT_HASH_SIZE; i++)
 		INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]);
 	nn->reclaim_str_hashtbl_size = 0;
+	init_rwsem(&nn->reclaim_str_hashtbl_lock);
 	set_bit(NFSD_NET_TRACK_RECLAIM_COMPLETES, &nn->flags);
 	atomic_set(&nn->nr_reclaim_complete, 0);

fs/nfsd/nfs4state.c +55 -6

122 lines not on this page · raw message

Sasha Levin

maintainer

2026-09-05 11:03 UTC #1 lore raw

PATCH 1/1 nfsd: dedup nfs4_client_to_reclaim inserts

From: Jeff Layton <[email protected]>

[ Upstream commit 9b57793863f69c608691c98e57c2f9be2db9dfed ]

    boot:    load_recdir()
               nfs4_client_to_reclaim(name)   /* entry #1, size++ */

    grace:   RECLAIM_COMPLETE
               __nfsd4_create_reclaim_record_grace()
                 nfs4_client_to_reclaim(name) /* entry #2, size++ */