linux-kernel - Re: [PATCH v2] NFSv4.1: handle memory allocation failure in nfs4_schedule_state

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Date:   Wed, 16 Nov 2022 18:54:31 +0800
From:   ChenXiaoSong <chenxiaosong2@...wei.com>
To:     <trond.myklebust@...merspace.com>
CC:     <linux-nfs@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yi.zhang@...wei.com>, <zhangxiaoxu5@...wei.com>,
        <yanaijie@...wei.com>, <anna@...nel.org>
Subject: Re: [PATCH v2] NFSv4.1: handle memory allocation failure in
 nfs4_schedule_state_manager()

Hi Trond:

Do you have any suggestions for this patch ?

在 2022/11/12 15:30, ChenXiaoSong 写道:
> If memory allocation fail in nfs4_schedule_state_manager() when mount
> NFSv4.1/NFSv4.2, nfs4_run_state_manager() will not be called, and current
> construction state will never be marked as ready or failed,
> nfs_wait_client_init_complete() will wait forever, as shown below:
> 
>    syscall(mount)
>    ...
>      nfs4_init_client
>        nfs4_discover_server_trunking
>          nfs41_discover_server_trunking
>            nfs4_schedule_state_manager
>              kthread_run /* nfs4_run_state_manager() will not be called */
>                kthread_create
>                  kthread_create_on_node
>                    __kthread_create_on_node
>                      create = kmalloc() = NULL
>                      return ERR_PTR(-ENOMEM)
>            nfs_wait_client_init_complete /* wait forever */
> 
> Fix this by checking return value of nfs4_schedule_state_manager() which
> can indicate whether kernel thread is created successful.
> 
> Signed-off-by: ChenXiaoSong <chenxiaosong2@...wei.com>
> ---
>   fs/nfs/nfs4_fs.h   |  2 +-
>   fs/nfs/nfs4state.c | 17 +++++++++++------
>   2 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
> index cfef738d765e..74c6d1504010 100644
> --- a/fs/nfs/nfs4_fs.h
> +++ b/fs/nfs/nfs4_fs.h
> @@ -502,7 +502,7 @@ extern int nfs4_state_mark_reclaim_nograce(struct nfs_client *, struct nfs4_stat
>   extern void nfs4_schedule_lease_recovery(struct nfs_client *);
>   extern int nfs4_wait_clnt_recover(struct nfs_client *clp);
>   extern int nfs4_client_recover_expired_lease(struct nfs_client *clp);
> -extern void nfs4_schedule_state_manager(struct nfs_client *);
> +extern int nfs4_schedule_state_manager(struct nfs_client *);
>   extern void nfs4_schedule_path_down_recovery(struct nfs_client *clp);
>   extern int nfs4_schedule_stateid_recovery(const struct nfs_server *, struct nfs4_state *);
>   extern int nfs4_schedule_migration_recovery(const struct nfs_server *);
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index a2d2d5d1b088..e32739fb9151 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -376,8 +376,9 @@ int nfs41_discover_server_trunking(struct nfs_client *clp,
>   		else
>   			set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
>   	}
> -	nfs4_schedule_state_manager(clp);
> -	status = nfs_wait_client_init_complete(clp);
> +	status = nfs4_schedule_state_manager(clp);
> +	if (!status)
> +		status = nfs_wait_client_init_complete(clp);
>   	if (status < 0)
>   		nfs_put_client(clp);
>   	return status;
> @@ -1201,11 +1202,12 @@ static void nfs4_clear_state_manager_bit(struct nfs_client *clp)
>   /*
>    * Schedule the nfs_client asynchronous state management routine
>    */
> -void nfs4_schedule_state_manager(struct nfs_client *clp)
> +int nfs4_schedule_state_manager(struct nfs_client *clp)
>   {
>   	struct task_struct *task;
>   	char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
>   	struct rpc_clnt *cl = clp->cl_rpcclient;
> +	int ret = 0;
>   
>   	while (cl != cl->cl_parent)
>   		cl = cl->cl_parent;
> @@ -1213,7 +1215,8 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
>   	set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
>   	if (test_and_set_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state) != 0) {
>   		wake_up_var(&clp->cl_state);
> -		return;
> +		ret = -EIO;
> +		goto out;
>   	}
>   	set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
>   	__module_get(THIS_MODULE);
> @@ -1228,13 +1231,15 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
>   	rcu_read_unlock();
>   	task = kthread_run(nfs4_run_state_manager, clp, "%s", buf);
>   	if (IS_ERR(task)) {
> -		printk(KERN_ERR "%s: kthread_run: %ld\n",
> -			__func__, PTR_ERR(task));
> +		ret = PTR_ERR(task);
> +		printk(KERN_ERR "%s: kthread_run: %d\n", __func__, ret);
>   		nfs4_clear_state_manager_bit(clp);
>   		clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
>   		nfs_put_client(clp);
>   		module_put(THIS_MODULE);
>   	}
> +out:
> +	return ret;
>   }
>   
>   /*
>