From: Wenbin Zeng <wenbin.zeng@gmail.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: davem@davemloft.net, bfields@fieldses.org, jlayton@kernel.org,
trond.myklebust@hammerspace.com, anna.schumaker@netapp.com,
wenbinzeng@tencent.com, dsahern@gmail.com,
nicolas.dichtel@6wind.com, willy@infradead.org,
edumazet@google.com, jakub.kicinski@netronome.com,
tyhicks@canonical.com, chuck.lever@oracle.com, neilb@suse.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: Re: [PATCH 1/3] nsfs: add evict callback into struct proc_ns_operations
Date: Sun, 5 May 2019 00:08:17 +0800 [thread overview]
Message-ID: <20190504160817.GA15804@bridge> (raw)
In-Reply-To: <20190502030406.GT23075@ZenIV.linux.org.uk>
On Thu, May 02, 2019 at 04:04:06AM +0100, Al Viro wrote:
> On Wed, May 01, 2019 at 02:42:23PM +0800, Wenbin Zeng wrote:
> > The newly added evict callback shall be called by nsfs_evict(). Currently
> > only put() callback is called in nsfs_evict(), it is not able to release
> > all netns refcount, for example, a rpc client holds two netns refcounts,
> > these refcounts are supposed to be released when the rpc client is freed,
> > but the code to free rpc client is normally triggered by put() callback
> > only when netns refcount gets to 0, specifically:
> > refcount=0 -> cleanup_net() -> ops_exit_list -> free rpc client
> > But netns refcount will never get to 0 before rpc client gets freed, to
> > break the deadlock, the code to free rpc client can be put into the newly
> > added evict callback.
> >
> > Signed-off-by: Wenbin Zeng <wenbinzeng@tencent.com>
> > ---
> > fs/nsfs.c | 2 ++
> > include/linux/proc_ns.h | 1 +
> > 2 files changed, 3 insertions(+)
> >
> > diff --git a/fs/nsfs.c b/fs/nsfs.c
> > index 60702d6..5939b12 100644
> > --- a/fs/nsfs.c
> > +++ b/fs/nsfs.c
> > @@ -49,6 +49,8 @@ static void nsfs_evict(struct inode *inode)
> > struct ns_common *ns = inode->i_private;
> > clear_inode(inode);
> > ns->ops->put(ns);
> > + if (ns->ops->evict)
> > + ns->ops->evict(ns);
>
> What's to guarantee that ns will not be freed by ->put()?
> Confused...
Hi Al, thank you very much. You are absolutely right.
->evict() should be called before ->put(), i.e.:
@@ -49,6 +49,8 @@ static void nsfs_evict(struct inode *inode)
struct ns_common *ns = inode->i_private;
clear_inode(inode);
+ if (ns->ops->evict)
+ ns->ops->evict(ns);
ns->ops->put(ns);
}
Does this look good?
next prev parent reply other threads:[~2019-05-04 16:08 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-01 6:42 [PATCH 0/3] auth_gss: netns refcount leaks when use-gss-proxy==1 Wenbin Zeng
2019-05-01 6:42 ` [PATCH 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-05-02 3:04 ` Al Viro
2019-05-04 16:08 ` Wenbin Zeng [this message]
2019-05-01 6:42 ` [PATCH 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-05-04 4:10 ` David Miller
2019-05-01 6:42 ` [PATCH 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-05-09 20:52 ` [PATCH 0/3] auth_gss: netns refcount leaks " J. Bruce Fields
2019-05-10 5:09 ` Wenbin Zeng
2019-05-10 6:36 ` [PATCH v2 " Wenbin Zeng
2019-05-10 6:36 ` [PATCH v2 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-05-10 6:36 ` [PATCH v2 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-05-10 22:13 ` David Miller
2019-05-10 6:36 ` [PATCH v2 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-05-15 1:03 ` [PATCH v2 0/3] auth_gss: netns refcount leaks " J. Bruce Fields
2019-06-12 8:37 ` Wenbin Zeng
2019-06-12 15:52 ` J. Bruce Fields
2021-09-07 14:48 ` wanghai (M)
2021-09-08 20:51 ` J. Bruce Fields
2021-09-09 2:52 ` wanghai (M)
2021-09-09 19:52 ` J. Bruce Fields
2019-06-12 12:09 ` [PATCH v3 " Wenbin Zeng
2019-06-12 12:09 ` [PATCH v3 1/3] nsfs: add evict callback into struct proc_ns_operations Wenbin Zeng
2019-06-12 12:09 ` [PATCH v3 2/3] netns: add netns_evict into netns_operations Wenbin Zeng
2019-06-12 12:09 ` [PATCH v3 3/3] auth_gss: fix deadlock that blocks rpcsec_gss_exit_net when use-gss-proxy==1 Wenbin Zeng
2019-08-01 19:53 ` [PATCH v3 0/3] auth_gss: netns refcount leaks " J. Bruce Fields
2021-08-28 11:26 ` wanghai (M)
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