linux-nvdimm.lists.01.org archive mirror
 help / color / mirror / Atom feed
From: Liu Bo <bo.liu@linux.alibaba.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, virtio-fs@redhat.com,
	miklos@szeredi.hu, stefanha@redhat.com, dgilbert@redhat.com,
	mst@redhat.com
Subject: Re: [PATCH 20/20] fuse,virtiofs: Add logic to free up a memory range
Date: Thu, 12 Mar 2020 01:24:30 +0800	[thread overview]
Message-ID: <20200311172429.wmiflrlube3k2rkw@rsjd01523.et2sqa> (raw)
In-Reply-To: <20200311125923.GA83257@redhat.com>

On Wed, Mar 11, 2020 at 08:59:23AM -0400, Vivek Goyal wrote:
> On Wed, Mar 11, 2020 at 01:16:42PM +0800, Liu Bo wrote:
> 
> [..]
> > > @@ -719,6 +723,7 @@ void fuse_conn_put(struct fuse_conn *fc)
> > >  	if (refcount_dec_and_test(&fc->count)) {
> > >  		struct fuse_iqueue *fiq = &fc->iq;
> > >  
> > > +		flush_delayed_work(&fc->dax_free_work);
> > 
> > Today while debugging another case, I realized that flushing work here
> > at the very last fuse_conn_put() is a bit too late, here's my analysis,
> > 
> >          umount                                                   kthread
> > 
> > deactivate_locked_super
> >   ->virtio_kill_sb                                            try_to_free_dmap_chunks
> >     ->generic_shutdown_super                                    ->igrab()
> >                                                                 ...
> >      ->evict_inodes()  -> check all inodes' count
> >      ->fuse_conn_put                                            ->iput
> >  ->virtio_fs_free_devs
> >    ->fuse_dev_free
> >      ->fuse_conn_put // vq1
> >    ->fuse_dev_free
> >      ->fuse_conn_put // vq2
> >        ->flush_delayed_work
> > 
> > The above can end up with a warning message reported by evict_inodes()
> > about stable inodes.
> 
> Hi Liu Bo,
> 
> Which warning is that? Can you point me to it in code.
>

Hmm, it was actually in generic_shutdow_super,
---
              printk("VFS: Busy inodes after unmount of %s. "
                           "Self-destruct in 5 seconds.  Have a nice day...\n",
---

> > So I think it's necessary to put either
> > cancel_delayed_work_sync() or flush_delayed_work() before going to
> > generic_shutdown_super().
> 
> In general I agree that shutting down memory range freeing worker
> earling in unmount/shutdown sequence makes sense. It does not seem
> to help to let it run while filesystem is going away. How about following
> patch.
> 
> ---
>  fs/fuse/inode.c     |    1 -
>  fs/fuse/virtio_fs.c |    5 +++++
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> Index: redhat-linux/fs/fuse/virtio_fs.c
> ===================================================================
> --- redhat-linux.orig/fs/fuse/virtio_fs.c	2020-03-10 14:11:10.970284651 -0400
> +++ redhat-linux/fs/fuse/virtio_fs.c	2020-03-11 08:27:08.103330039 -0400
> @@ -1295,6 +1295,11 @@ static void virtio_kill_sb(struct super_
>  	vfs = fc->iq.priv;
>  	fsvq = &vfs->vqs[VQ_HIPRIO];
>  
> +	/* Stop dax worker. Soon evict_inodes() will be called which will
> +	 * free all memory ranges belonging to all inodes.
> +	 */
> +	flush_delayed_work(&fc->dax_free_work);
> +
>  	/* Stop forget queue. Soon destroy will be sent */
>  	spin_lock(&fsvq->lock);
>  	fsvq->connected = false;
> Index: redhat-linux/fs/fuse/inode.c
> ===================================================================
> --- redhat-linux.orig/fs/fuse/inode.c	2020-03-10 09:13:35.132565666 -0400
> +++ redhat-linux/fs/fuse/inode.c	2020-03-11 08:22:02.685330039 -0400
> @@ -723,7 +723,6 @@ void fuse_conn_put(struct fuse_conn *fc)
>  	if (refcount_dec_and_test(&fc->count)) {
>  		struct fuse_iqueue *fiq = &fc->iq;
>  
> -		flush_delayed_work(&fc->dax_free_work);
>  		if (fc->dax_dev)
>  			fuse_free_dax_mem_ranges(&fc->free_ranges);
>  		if (fiq->ops->release)

Looks good, it should be safe now, but I feel like
cancel_delayed_work_sync() would be a good alternative for "stop dax
worker".

Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com>

Fine with either folding directly or a new patch, thanks for fixing it.

thanks,
-liubo
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org

  reply	other threads:[~2020-03-11 17:24 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-04 16:58 [PATCH 00/20] virtiofs: Add DAX support Vivek Goyal
2020-03-04 16:58 ` [PATCH 01/20] dax: Modify bdev_dax_pgoff() to handle NULL bdev Vivek Goyal
2020-03-04 16:58 ` [PATCH 02/20] dax: Create a range version of dax_layout_busy_page() Vivek Goyal
2020-03-10 15:19   ` Ira Weiny
2020-03-10 20:29     ` Vivek Goyal
2020-03-04 16:58 ` [PATCH 03/20] virtio: Add get_shm_region method Vivek Goyal
2020-03-10 10:53   ` Stefan Hajnoczi
2020-03-04 16:58 ` [PATCH 04/20] virtio: Implement get_shm_region for PCI transport Vivek Goyal
2020-03-10 11:04   ` Stefan Hajnoczi
2020-03-10 18:19     ` Vivek Goyal
2020-03-11 17:34       ` Stefan Hajnoczi
2020-03-11 19:29         ` Vivek Goyal
2020-03-10 11:12   ` Michael S. Tsirkin
2020-03-10 18:47     ` Vivek Goyal
2020-03-10 21:27       ` Michael S. Tsirkin
2020-03-04 16:58 ` [PATCH 05/20] virtio: Implement get_shm_region for MMIO transport Vivek Goyal
2020-03-10 11:06   ` Stefan Hajnoczi
2020-03-04 16:58 ` [PATCH 06/20] virtiofs: Provide a helper function for virtqueue initialization Vivek Goyal
2020-03-10 14:10   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 07/20] fuse: Get rid of no_mount_options Vivek Goyal
2020-03-10 14:12   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 08/20] fuse,virtiofs: Add a mount option to enable dax Vivek Goyal
2020-03-10 14:16   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 09/20] virtio_fs, dax: Set up virtio_fs dax_device Vivek Goyal
2020-03-04 16:58 ` [PATCH 10/20] fuse,virtiofs: Keep a list of free dax memory ranges Vivek Goyal
2020-03-10 19:29   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 11/20] fuse: implement FUSE_INIT map_alignment field Vivek Goyal
2020-03-10 19:31   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 12/20] fuse: Introduce setupmapping/removemapping commands Vivek Goyal
2020-03-10 19:49   ` Miklos Szeredi
2020-03-10 20:33     ` Vivek Goyal
2020-03-11  7:03       ` Amir Goldstein
2020-03-11 14:19         ` Miklos Szeredi
2020-03-11 14:41           ` Vivek Goyal
2020-03-11 15:12             ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 13/20] fuse, dax: Implement dax read/write operations Vivek Goyal
2020-03-12  9:43   ` Miklos Szeredi
2020-03-12 16:02     ` Vivek Goyal
2020-03-13 10:18       ` Miklos Szeredi
2020-03-13 13:41         ` Vivek Goyal
2020-04-04  0:25   ` Liu Bo
2020-04-14 12:54     ` Vivek Goyal
2020-03-04 16:58 ` [PATCH 14/20] fuse,dax: add DAX mmap support Vivek Goyal
2020-03-04 16:58 ` [PATCH 15/20] fuse, dax: Take ->i_mmap_sem lock during dax page fault Vivek Goyal
2020-03-04 16:58 ` [PATCH 16/20] fuse,virtiofs: Define dax address space operations Vivek Goyal
2020-03-04 16:58 ` [PATCH 17/20] fuse,virtiofs: Maintain a list of busy elements Vivek Goyal
2020-03-04 16:58 ` [PATCH 18/20] fuse: Release file in process context Vivek Goyal
2020-03-04 16:58 ` [PATCH 19/20] fuse: Take inode lock for dax inode truncation Vivek Goyal
2020-03-04 16:58 ` [PATCH 20/20] fuse,virtiofs: Add logic to free up a memory range Vivek Goyal
2020-03-11  5:16   ` Liu Bo
2020-03-11 12:59     ` Vivek Goyal
2020-03-11 17:24       ` Liu Bo [this message]
2020-03-26  0:09   ` Liu Bo
2020-03-27 14:01     ` Vivek Goyal
2020-03-27 22:06       ` Liu Bo
2020-04-14 19:30         ` Vivek Goyal
2020-04-15 17:22           ` Liu Bo
2020-04-16 19:05             ` Vivek Goyal
2020-04-17 18:05               ` Liu Bo
2020-03-11  5:22 ` [PATCH 00/20] virtiofs: Add DAX support Amir Goldstein
2020-03-11 13:09   ` Vivek Goyal
2020-03-11 18:48   ` Vivek Goyal
2020-03-11 19:32     ` Amir Goldstein
2020-03-11 19:39       ` Vivek Goyal
2020-03-11 13:38 ` Patrick Ohly
2020-03-16 13:02   ` Vivek Goyal
2020-03-17  8:28     ` Patrick Ohly

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200311172429.wmiflrlube3k2rkw@rsjd01523.et2sqa \
    --to=bo.liu@linux.alibaba.com \
    --cc=dgilbert@redhat.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nvdimm@lists.01.org \
    --cc=miklos@szeredi.hu \
    --cc=mst@redhat.com \
    --cc=stefanha@redhat.com \
    --cc=vgoyal@redhat.com \
    --cc=virtio-fs@redhat.com \
    --subject='Re: [PATCH 20/20] fuse,virtiofs: Add logic to free up a memory range' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).