From: Stefano Garzarella <sgarzare@redhat.com>
To: Dexuan Cui <decui@microsoft.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
"sashal@kernel.org" <sashal@kernel.org>,
"stefanha@redhat.com" <stefanha@redhat.com>,
"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
"arnd@arndb.de" <arnd@arndb.de>,
"deepa.kernel@gmail.com" <deepa.kernel@gmail.com>,
"ytht.net@gmail.com" <ytht.net@gmail.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
Michael Kelley <mikelley@microsoft.com>,
"jhansen@vmware.com" <jhansen@vmware.com>
Subject: Re: [PATCH net v2] vsock: Fix a lockdep warning in __vsock_release()
Date: Thu, 26 Sep 2019 09:47:49 +0200 [thread overview]
Message-ID: <20190926074749.sltehhkcgfduu7n2@steredhat.homenet.telecomitalia.it> (raw)
In-Reply-To: <1569460241-57800-1-git-send-email-decui@microsoft.com>
Hi Dexuan,
On Thu, Sep 26, 2019 at 01:11:27AM +0000, Dexuan Cui wrote:
> Lockdep is unhappy if two locks from the same class are held.
>
> Fix the below warning for hyperv and virtio sockets (vmci socket code
> doesn't have the issue) by using lock_sock_nested() when __vsock_release()
> is called recursively:
>
> ============================================
> WARNING: possible recursive locking detected
> 5.3.0+ #1 Not tainted
> --------------------------------------------
> server/1795 is trying to acquire lock:
> ffff8880c5158990 (sk_lock-AF_VSOCK){+.+.}, at: hvs_release+0x10/0x120 [hv_sock]
>
> but task is already holding lock:
> ffff8880c5158150 (sk_lock-AF_VSOCK){+.+.}, at: __vsock_release+0x2e/0xf0 [vsock]
>
> other info that might help us debug this:
> Possible unsafe locking scenario:
>
> CPU0
> ----
> lock(sk_lock-AF_VSOCK);
> lock(sk_lock-AF_VSOCK);
>
> *** DEADLOCK ***
>
> May be due to missing lock nesting notation
>
> 2 locks held by server/1795:
> #0: ffff8880c5d05ff8 (&sb->s_type->i_mutex_key#10){+.+.}, at: __sock_release+0x2d/0xa0
> #1: ffff8880c5158150 (sk_lock-AF_VSOCK){+.+.}, at: __vsock_release+0x2e/0xf0 [vsock]
>
> stack backtrace:
> CPU: 5 PID: 1795 Comm: server Not tainted 5.3.0+ #1
> Call Trace:
> dump_stack+0x67/0x90
> __lock_acquire.cold.67+0xd2/0x20b
> lock_acquire+0xb5/0x1c0
> lock_sock_nested+0x6d/0x90
> hvs_release+0x10/0x120 [hv_sock]
> __vsock_release+0x24/0xf0 [vsock]
> __vsock_release+0xa0/0xf0 [vsock]
> vsock_release+0x12/0x30 [vsock]
> __sock_release+0x37/0xa0
> sock_close+0x14/0x20
> __fput+0xc1/0x250
> task_work_run+0x98/0xc0
> do_exit+0x344/0xc60
> do_group_exit+0x47/0xb0
> get_signal+0x15c/0xc50
> do_signal+0x30/0x720
> exit_to_usermode_loop+0x50/0xa0
> do_syscall_64+0x24e/0x270
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x7f4184e85f31
>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> ---
>
> NOTE: I only tested the code on Hyper-V. I can not test the code for
> virtio socket, as I don't have a KVM host. :-( Sorry.
>
> @Stefan, @Stefano: please review & test the patch for virtio socket,
> and let me know if the patch breaks anything. Thanks!
Comment below, I'll test it ASAP!
>
> Changes in v2:
> Avoid the duplication of code in v1: https://lkml.org/lkml/2019/8/19/1361
> Also fix virtio socket code.
>
> net/vmw_vsock/af_vsock.c | 19 +++++++++++++++----
> net/vmw_vsock/hyperv_transport.c | 2 +-
> net/vmw_vsock/virtio_transport_common.c | 2 +-
> 3 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index ab47bf3ab66e..dbae4373cbab 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -638,8 +638,10 @@ struct sock *__vsock_create(struct net *net,
> }
> EXPORT_SYMBOL_GPL(__vsock_create);
>
> -static void __vsock_release(struct sock *sk)
> +static void __vsock_release(struct sock *sk, int level)
> {
> + WARN_ON(level != 1 && level != 2);
> +
> if (sk) {
> struct sk_buff *skb;
> struct sock *pending;
> @@ -648,9 +650,18 @@ static void __vsock_release(struct sock *sk)
> vsk = vsock_sk(sk);
> pending = NULL; /* Compiler warning. */
>
> + /* The release call is supposed to use lock_sock_nested()
> + * rather than lock_sock(), if a sock lock should be acquired.
> + */
> transport->release(vsk);
>
> - lock_sock(sk);
> + /* When "level" is 2, use the nested version to avoid the
> + * warning "possible recursive locking detected".
> + */
> + if (level == 1)
> + lock_sock(sk);
Since lock_sock() calls lock_sock_nested(sk, 0), could we use directly
lock_sock_nested(sk, level) with level = 0 in vsock_release() and
level = SINGLE_DEPTH_NESTING here in the while loop?
> + else
> + lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
> sock_orphan(sk);
> sk->sk_shutdown = SHUTDOWN_MASK;
>
> @@ -659,7 +670,7 @@ static void __vsock_release(struct sock *sk)
>
> /* Clean up any sockets that never were accepted. */
> while ((pending = vsock_dequeue_accept(sk)) != NULL) {
> - __vsock_release(pending);
> + __vsock_release(pending, 2);
> sock_put(pending);
> }
>
> @@ -708,7 +719,7 @@ EXPORT_SYMBOL_GPL(vsock_stream_has_space);
>
> static int vsock_release(struct socket *sock)
> {
> - __vsock_release(sock->sk);
> + __vsock_release(sock->sk, 1);
> sock->sk = NULL;
> sock->state = SS_FREE;
>
> diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c
> index 261521d286d6..c443db7af8d4 100644
> --- a/net/vmw_vsock/hyperv_transport.c
> +++ b/net/vmw_vsock/hyperv_transport.c
> @@ -559,7 +559,7 @@ static void hvs_release(struct vsock_sock *vsk)
> struct sock *sk = sk_vsock(vsk);
> bool remove_sock;
>
> - lock_sock(sk);
> + lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
> remove_sock = hvs_close_lock_held(vsk);
> release_sock(sk);
> if (remove_sock)
> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
> index 5bb70c692b1e..a666ef8fc54e 100644
> --- a/net/vmw_vsock/virtio_transport_common.c
> +++ b/net/vmw_vsock/virtio_transport_common.c
> @@ -820,7 +820,7 @@ void virtio_transport_release(struct vsock_sock *vsk)
> struct sock *sk = &vsk->sk;
> bool remove_sock = true;
>
> - lock_sock(sk);
> + lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
> if (sk->sk_type == SOCK_STREAM)
> remove_sock = virtio_transport_close(vsk);
>
Thanks,
Stefano
next prev parent reply other threads:[~2019-09-26 7:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 1:11 [PATCH net v2] vsock: Fix a lockdep warning in __vsock_release() Dexuan Cui
2019-09-26 7:47 ` Stefano Garzarella [this message]
2019-09-27 5:37 ` Dexuan Cui
2019-09-27 8:32 ` Stefano Garzarella
2019-09-30 13:51 ` Stefano Garzarella
2019-09-30 18:33 ` Dexuan Cui
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=20190926074749.sltehhkcgfduu7n2@steredhat.homenet.telecomitalia.it \
--to=sgarzare@redhat.com \
--cc=arnd@arndb.de \
--cc=davem@davemloft.net \
--cc=decui@microsoft.com \
--cc=deepa.kernel@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=haiyangz@microsoft.com \
--cc=jhansen@vmware.com \
--cc=kvm@vger.kernel.org \
--cc=kys@microsoft.com \
--cc=linux-hyperv@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mikelley@microsoft.com \
--cc=netdev@vger.kernel.org \
--cc=sashal@kernel.org \
--cc=stefanha@redhat.com \
--cc=sthemmin@microsoft.com \
--cc=tglx@linutronix.de \
--cc=virtualization@lists.linux-foundation.org \
--cc=ytht.net@gmail.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).