nfs41_init_clientid does not signal a failure condition from nfs4_proc_exchange_id and nfs4_proc_create_session to a client which may lead to mount syscall indefinitely blocked in the following stack trace: nfs_wait_client_init_complete nfs41_discover_server_trunking nfs4_discover_server_trunking nfs4_init_client nfs4_set_client nfs4_create_server nfs4_try_get_tree vfs_get_tree do_new_mount __se_sys_mount and the client stuck in uninitialized state. In addition to this all subsequent mount calls would also get blocked in nfs_match_client waiting for the uninitialized client to finish initialization: nfs_wait_client_init_complete nfs_match_client nfs_get_client nfs4_set_client nfs4_create_server nfs4_try_get_tree vfs_get_tree do_new_mount __se_sys_mount To avoid this situation propagate error condition to the mount thread and let mount syscall fail properly. To: Trond Myklebust <trondmy@xxxxxxxxxx> To: Anna Schumaker <anna@xxxxxxxxxx> Cc: linux-nfs@xxxxxxxxxxxxxxx Cc: jbongio@xxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/stable/20240906-nfs-mount-deadlock-fix-v1-1-ea1aef533f9c%40google.com Signed-off-by: Oleksandr Tymoshenko <ovt@xxxxxxxxxx> --- Changes in v2: - Added correct To/Cc entries to the commit message - Link to v1: https://lore.kernel.org/r/20240906-nfs-mount-deadlock-fix-v1-1-ea1aef533f9c@xxxxxxxxxx --- fs/nfs/nfs4state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c index 877f682b45f2..54ad3440ad2b 100644 --- a/fs/nfs/nfs4state.c +++ b/fs/nfs/nfs4state.c @@ -335,8 +335,8 @@ int nfs41_init_clientid(struct nfs_client *clp, const struct cred *cred) if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R)) nfs4_state_start_reclaim_reboot(clp); nfs41_finish_session_reset(clp); - nfs_mark_client_ready(clp, NFS_CS_READY); out: + nfs_mark_client_ready(clp, status == 0 ? NFS_CS_READY : status); return status; } --- base-commit: ad618736883b8970f66af799e34007475fe33a68 change-id: 20240906-nfs-mount-deadlock-fix-55c14b38e088 Best regards, -- Oleksandr Tymoshenko <ovt@xxxxxxxxxx>
