This is a note to let you know that I've just added the patch titled
NFSv4: nfs4_state_manager() vs. nfs_server_remove_lists()
to the 3.16-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:
nfsv4-nfs4_state_manager-vs.-nfs_server_remove_lists.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 080af20cc945d110f9912d01cf6b66f94a375b8d Mon Sep 17 00:00:00 2001
From: Steve Dickson <steved@xxxxxxxxxx>
Date: Thu, 18 Sep 2014 09:13:17 -0400
Subject: NFSv4: nfs4_state_manager() vs. nfs_server_remove_lists()
From: Steve Dickson <steved@xxxxxxxxxx>
commit 080af20cc945d110f9912d01cf6b66f94a375b8d upstream.
There is a race between nfs4_state_manager() and
nfs_server_remove_lists() that happens during a nfsv3 mount.
The v3 mount notices there is already a supper block so
nfs_server_remove_lists() called which uses the nfs_client_lock
spin lock to synchronize access to the client list.
At the same time nfs4_state_manager() is running through
the client list looking for work to do, using the same
lock. When nfs4_state_manager() wins the race to the
list, a v3 client pointer is found and not ignored
properly which causes the panic.
Moving some protocol checks before the state checking
avoids the panic.
Signed-off-by: Steve Dickson <steved@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/nfs4client.c | 38 ++++++++++++++++++++------------------
1 file changed, 20 insertions(+), 18 deletions(-)
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -482,6 +482,16 @@ int nfs40_walk_client_list(struct nfs_cl
spin_lock(&nn->nfs_client_lock);
list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+ if (pos->rpc_ops != new->rpc_ops)
+ continue;
+
+ if (pos->cl_proto != new->cl_proto)
+ continue;
+
+ if (pos->cl_minorversion != new->cl_minorversion)
+ continue;
+
/* If "pos" isn't marked ready, we can't trust the
* remaining fields in "pos" */
if (pos->cl_cons_state > NFS_CS_READY) {
@@ -501,15 +511,6 @@ int nfs40_walk_client_list(struct nfs_cl
if (pos->cl_cons_state != NFS_CS_READY)
continue;
- if (pos->rpc_ops != new->rpc_ops)
- continue;
-
- if (pos->cl_proto != new->cl_proto)
- continue;
-
- if (pos->cl_minorversion != new->cl_minorversion)
- continue;
-
if (pos->cl_clientid != new->cl_clientid)
continue;
@@ -622,6 +623,16 @@ int nfs41_walk_client_list(struct nfs_cl
spin_lock(&nn->nfs_client_lock);
list_for_each_entry(pos, &nn->nfs_client_list, cl_share_link) {
+
+ if (pos->rpc_ops != new->rpc_ops)
+ continue;
+
+ if (pos->cl_proto != new->cl_proto)
+ continue;
+
+ if (pos->cl_minorversion != new->cl_minorversion)
+ continue;
+
/* If "pos" isn't marked ready, we can't trust the
* remaining fields in "pos", especially the client
* ID and serverowner fields. Wait for CREATE_SESSION
@@ -647,15 +658,6 @@ int nfs41_walk_client_list(struct nfs_cl
if (pos->cl_cons_state != NFS_CS_READY)
continue;
- if (pos->rpc_ops != new->rpc_ops)
- continue;
-
- if (pos->cl_proto != new->cl_proto)
- continue;
-
- if (pos->cl_minorversion != new->cl_minorversion)
- continue;
-
if (!nfs4_match_clientids(pos, new))
continue;
Patches currently in stable-queue which might be from steved@xxxxxxxxxx are
queue-3.16/nfsv4-nfs4_state_manager-vs.-nfs_server_remove_lists.patch
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