Re: kernel stable 4.9 - NFSv4 callback processes fills process table

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Sep 18, 2017 at 05:27:00PM +0200, Jan Hudoba wrote:
> hello,
> when using nfs with automount (umount every N secs), every mount creates
> "NFSv4 callback" process. after while these fills process table.
> 
> https://lists.debian.org/debian-kernel/2017/05/msg00193.html
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1427493
> 
> i have same problems. listed commits solved them.
> thanks for including patches.
> 
> "Aurelien Jarno:"
> 
> It seems the issues is fixed since 4.12-rc1 by the following set of
> commts:
> 
> 
> 
> |  commit ed6473ddc704a2005b9900ca08e236ebb2d8540a
> |  Author: Trond Myklebust <trond.myklebust@primarydata.com>
> |  Date:   Wed Apr 26 11:55:27 2017 -0400
> |
> |      NFSv4: Fix callback server shutdown
> |
> |      We want to use kthread_stop() in order to ensure the threads are
> |      shut down before we tear down the nfs_callback_info in
> nfs_callback_down.
> |
> |      Tested-and-reviewed-by: Kinglong Mee <kinglongmee@gmail.com>
> |      Reported-by: Kinglong Mee <kinglongmee@gmail.com>
> |      Fixes: bb6aeba736ba9 ("NFSv4.x: Switch to using
> svc_set_num_threads()...")
> |      Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> |      Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> |
> |  commit 9e0d87680d689f1758185851c3da6eafb16e71e1
> |  Author: Trond Myklebust <trond.myklebust@primarydata.com>
> |  Date:   Wed Apr 26 11:55:26 2017 -0400
> |
> |      SUNRPC: Refactor svc_set_num_threads()
> |
> |      Refactor to separate out the functions of starting and stopping
> threads
> |      so that they can be used in other helpers.
> |
> |      Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
> |      Tested-and-reviewed-by: Kinglong Mee <kinglongmee@gmail.com>
> |      Signed-off-by: J. Bruce Fields <bfields@redhat.com>
> |
> |  commit df807fffaabde625fa9adb82e3e5b88cdaa5709a
> |  Author: Kinglong Mee <kinglongmee@gmail.com>
> |  Date:   Thu Apr 27 11:13:38 2017 +0800
> |
> |      NFSv4.x/callback: Create the callback service through
> svc_create_pooled
> |
> |      As the comments for svc_set_num_threads() said,
> |      " Destroying threads relies on the service threads filling in
> |      rqstp->rq_task, which only the nfs ones do.  Assumes the serv
> |      has been created using svc_create_pooled()."
> |
> |      If creating service through svc_create(), the svc_pool_map_put()
> |      will be called in svc_destroy(), but the pool map isn't used.
> |      So that, the reference of pool map will be drop, the next using
> |      of pool map will get a zero npools.


Care to cc: the authors/maintainers of these patches to see if they
agree it should be backported?

thanks,

greg k-h