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From:   trondmy@kernel.org
To:     Anna Schumaker <Anna.Schumaker@netapp.com>
Cc:     linux-nfs@vger.kernel.org, Neil Brown <neilb@suse.de>
Subject: [PATCH 1/2] NFSv4: Fix a nfs4_state_manager() race
Date:   Sun, 17 Sep 2023 19:05:50 -0400
Message-ID: <20230917230551.30483-1-trondmy@kernel.org>
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From: Trond Myklebust <trond.myklebust@hammerspace.com>

If the NFS4CLNT_RUN_MANAGER flag got set just before we cleared
NFS4CLNT_MANAGER_RUNNING, then we might have won the race against
nfs4_schedule_state_manager(), and are responsible for handling the
recovery situation.

Fixes: aeabb3c96186 ("NFSv4: Fix a NFSv4 state manager deadlock")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 fs/nfs/nfs4state.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index e079987af4a3..0bc160fbabec 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2703,6 +2703,13 @@ static void nfs4_state_manager(struct nfs_client *clp)
 		nfs4_end_drain_session(clp);
 		nfs4_clear_state_manager_bit(clp);
 
+		if (test_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state) &&
+		    !test_and_set_bit(NFS4CLNT_MANAGER_RUNNING,
+				      &clp->cl_state)) {
+			memflags = memalloc_nofs_save();
+			continue;
+		}
+
 		if (!test_and_set_bit(NFS4CLNT_RECALL_RUNNING, &clp->cl_state)) {
 			if (test_and_clear_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state)) {
 				nfs_client_return_marked_delegations(clp);
-- 
2.41.0