This is a note to let you know that I've just added the patch titled NFSD: Fix possible sleep during nfsd4_release_lockowner() to the 5.18-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: nfsd-fix-possible-sleep-during-nfsd4_release_lockowner.patch and it can be found in the queue-5.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From ce3c4ad7f4ce5db7b4f08a1e237d8dd94b39180b Mon Sep 17 00:00:00 2001 From: Chuck Lever <chuck.lever@xxxxxxxxxx> Date: Sat, 21 May 2022 19:06:13 -0400 Subject: NFSD: Fix possible sleep during nfsd4_release_lockowner() From: Chuck Lever <chuck.lever@xxxxxxxxxx> commit ce3c4ad7f4ce5db7b4f08a1e237d8dd94b39180b upstream. nfsd4_release_lockowner() holds clp->cl_lock when it calls check_for_locks(). However, check_for_locks() calls nfsd_file_get() / nfsd_file_put() to access the backing inode's flc_posix list, and nfsd_file_put() can sleep if the inode was recently removed. Let's instead rely on the stateowner's reference count to gate whether the release is permitted. This should be a reliable indication of locks-in-use since file lock operations and ->lm_get_owner take appropriate references, which are released appropriately when file locks are removed. Reported-by: Dai Ngo <dai.ngo@xxxxxxxxxx> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nfsd/nfs4state.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -7330,16 +7330,12 @@ nfsd4_release_lockowner(struct svc_rqst if (sop->so_is_open_owner || !same_owner_str(sop, owner)) continue; - /* see if there are still any locks associated with it */ - lo = lockowner(sop); - list_for_each_entry(stp, &sop->so_stateids, st_perstateowner) { - if (check_for_locks(stp->st_stid.sc_file, lo)) { - status = nfserr_locks_held; - spin_unlock(&clp->cl_lock); - return status; - } + if (atomic_read(&sop->so_count) != 1) { + spin_unlock(&clp->cl_lock); + return nfserr_locks_held; } + lo = lockowner(sop); nfs4_get_stateowner(sop); break; } Patches currently in stable-queue which might be from chuck.lever@xxxxxxxxxx are queue-5.18/nfsd-fix-possible-sleep-during-nfsd4_release_lockowner.patch