[PATCH v2] NFSv4: fix a mount deadlock in NFS v4.1 client

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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>





[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux