Re: [PATCH 2/2] NFS: Don't allow waiting for exiting tasks

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2025-03-28 at 13:40 -0400, trondmy@kernel.org wrote:
> From: Trond Myklebust <trond.myklebust@hammerspace.com>
> 
> Once a task calls exit_signals() it can no longer be signalled. So do
> not allow it to do killable waits.
> 
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> ---
>  fs/nfs/inode.c    | 2 ++
>  fs/nfs/internal.h | 5 +++++
>  fs/nfs/nfs3proc.c | 2 +-
>  fs/nfs/nfs4proc.c | 9 +++++++--
>  4 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 1aa67fca69b2..119e447758b9 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -74,6 +74,8 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
>  
>  int nfs_wait_bit_killable(struct wait_bit_key *key, int mode)
>  {
> +	if (unlikely(nfs_current_task_exiting()))
> +		return -EINTR;
>  	schedule();
>  	if (signal_pending_state(mode, current))
>  		return -ERESTARTSYS;
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index fae2c7ae4acc..2133b3c20bad 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -912,6 +912,11 @@ static inline u32 nfs_stateid_hash(nfs4_stateid *stateid)
>  }
>  #endif
>  
> +static inline bool nfs_current_task_exiting(void)
> +{
> +	return (current->flags & PF_EXITING) != 0;
> +}
> +
>  static inline bool nfs_error_is_fatal(int err)
>  {
>  	switch (err) {
> diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
> index 0c3bc98cd999..c1736dbb92b6 100644
> --- a/fs/nfs/nfs3proc.c
> +++ b/fs/nfs/nfs3proc.c
> @@ -39,7 +39,7 @@ nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
>  		__set_current_state(TASK_KILLABLE|TASK_FREEZABLE_UNSAFE);
>  		schedule_timeout(NFS_JUKEBOX_RETRY_TIME);
>  		res = -ERESTARTSYS;
> -	} while (!fatal_signal_pending(current));
> +	} while (!fatal_signal_pending(current) && !nfs_current_task_exiting());
>  	return res;
>  }
>  
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 50be54e0f578..da97f87ecaa9 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -446,6 +446,8 @@ static int nfs4_delay_killable(long *timeout)
>  {
>  	might_sleep();
>  
> +	if (unlikely(nfs_current_task_exiting()))
> +		return -EINTR;
>  	__set_current_state(TASK_KILLABLE|TASK_FREEZABLE_UNSAFE);
>  	schedule_timeout(nfs4_update_delay(timeout));
>  	if (!__fatal_signal_pending(current))
> @@ -457,6 +459,8 @@ static int nfs4_delay_interruptible(long *timeout)
>  {
>  	might_sleep();
>  
> +	if (unlikely(nfs_current_task_exiting()))
> +		return -EINTR;
>  	__set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE_UNSAFE);
>  	schedule_timeout(nfs4_update_delay(timeout));
>  	if (!signal_pending(current))
> @@ -1777,7 +1781,8 @@ static void nfs_set_open_stateid_locked(struct nfs4_state *state,
>  		rcu_read_unlock();
>  		trace_nfs4_open_stateid_update_wait(state->inode, stateid, 0);
>  
> -		if (!fatal_signal_pending(current)) {
> +		if (!fatal_signal_pending(current) &&
> +		    !nfs_current_task_exiting()) {
>  			if (schedule_timeout(5*HZ) == 0)
>  				status = -EAGAIN;
>  			else
> @@ -3581,7 +3586,7 @@ static bool nfs4_refresh_open_old_stateid(nfs4_stateid *dst,
>  		write_sequnlock(&state->seqlock);
>  		trace_nfs4_close_stateid_update_wait(state->inode, dst, 0);
>  
> -		if (fatal_signal_pending(current))
> +		if (fatal_signal_pending(current) || nfs_current_task_exiting())
>  			status = -EINTR;
>  		else
>  			if (schedule_timeout(5*HZ) != 0)

Reviewed-by: Jeff Layton <jlayton@kernel.org>