linux-kernel - [PATCH 5.18 650/879] nfsd: destroy percpu stats counters after reply cache shutdown

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Date:   Tue,  7 Jun 2022 19:02:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Julian Schroeder <jumaco@...zon.com>,
        Chuck Lever <chuck.lever@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 650/879] nfsd: destroy percpu stats counters after reply cache shutdown

From: Julian Schroeder <jumaco@...zon.com>

[ Upstream commit fd5e363eac77ef81542db77ddad0559fa0f9204e ]

Upon nfsd shutdown any pending DRC cache is freed. DRC cache use is
tracked via a percpu counter. In the current code the percpu counter
is destroyed before. If any pending cache is still present,
percpu_counter_add is called with a percpu counter==NULL. This causes
a kernel crash.
The solution is to destroy the percpu counter after the cache is freed.

Fixes: e567b98ce9a4b (“nfsd: protect concurrent access to nfsd stats counters”)
Signed-off-by: Julian Schroeder <jumaco@...zon.com>
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/nfsd/nfscache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 0b3f12aa37ff..7da88bdc0d6c 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -206,7 +206,6 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
 	struct svc_cacherep	*rp;
 	unsigned int i;
 
-	nfsd_reply_cache_stats_destroy(nn);
 	unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
 
 	for (i = 0; i < nn->drc_hashsize; i++) {
@@ -217,6 +216,7 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
 									rp, nn);
 		}
 	}
+	nfsd_reply_cache_stats_destroy(nn);
 
 	kvfree(nn->drc_hashtbl);
 	nn->drc_hashtbl = NULL;
-- 
2.35.1