From: Peter Hurley <peter@hurleysoftware.com>
To: David Miller <davem@davemloft.net>
Cc: sasha.levin@oracle.com, samuel@sortiz.org,
gregkh@linuxfoundation.org, jslaby@suse.cz,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ircomm: release tty before sleeping potentially indefintely
Date: Sun, 03 Mar 2013 21:23:04 -0500 [thread overview]
Message-ID: <1362363784.3221.141.camel@thor.lan> (raw)
In-Reply-To: <20130303.174739.1195645942179862011.davem@davemloft.net>
On Sun, 2013-03-03 at 17:47 -0500, David Miller wrote:
> From: Sasha Levin <sasha.levin@oracle.com>
> Date: Sun, 3 Mar 2013 17:35:53 -0500
>
> > ircomm_tty_block_til_ready would hold tty lock while blocking. Since the sleep
> > might take a long time we can prevent other processes from accessing the tty,
> > causing hung tasks and a dead tty.
> >
> > Diagnosed-by: Peter Hurley <peter@hurleysoftware.com>
> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
>
> But then you invalidate all of the tty state tests made under
> the lock at the beginning of this function, before enterring
> the loop. If you drop the lock, those pieces of state could
> change.
>
> I'm not applying this.
BTW, Sasha deserves a medal for finding and fixing this. Here's the
initial report [1] by him from Halloween. And he doesn't even have an IR
device.
So this fix needs to be cc'd to stable too.
Regards,
Peter Hurley
[1]
On Wed, 2012-10-31 at 16:10 -0400, Sasha Levin wrote:
On 10/31/2012 11:32 AM, Jiri Slaby wrote:
> > On 10/31/2012 04:30 PM, Sasha Levin wrote:
> >> On Wed, Oct 31, 2012 at 8:53 AM, Jiri Slaby <jslaby@suse.cz> wrote:
> >>> On 10/25/2012 08:02 PM, Sasha Levin wrote:
> >>>> Fuzzing with trinity inside a KVM tools (lkvm) guest with -next kernel
> >>>> uncovered the following warning:
> >>>
> >>> I cannot reproduce that :(. Do you still see it?
> >>
> >> Yes, it reproduces pretty easily while fuzzing.
> >
> > What is your exact setup? I tried trinity with 100 000 syscalls inside
> > KVM with an LDEP-enabled kernel. How many serial ports do you have in
> > the guest? Any USB serials in there?
>
> btw, I'm also seeing the following lockups, don't know if it's related:
>
>
> [ 2283.070569] INFO: task trinity-child20:9161 blocked for more than 120 seconds.
> [ 2283.071775] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 2283.074673] trinity-child20 D ffff8800276cb000 5424 9161 6364 0x00000000
> [ 2283.076018] ffff880059d9da58 0000000000000002 0000000000000002 0000000000000000
> [ 2283.077393] ffff880059d7b000 ffff880059d9dfd8 ffff880059d9dfd8 ffff880059d9dfd8
> [ 2283.078763] ffff8800276cb000 ffff880059d7b000 ffff880059d9da78 ffff88001a095180
> [ 2283.084144] Call Trace:
> [ 2283.085039] [<ffffffff83a98bd5>] schedule+0x55/0x60
> [ 2283.086748] [<ffffffff83a98bf3>] schedule_preempt_disabled+0x13/0x20
> [ 2283.089000] [<ffffffff83a9735d>] __mutex_lock_common+0x36d/0x5a0
> [ 2283.090658] [<ffffffff83a9afb3>] ? tty_lock_nested+0x73/0x80
> [ 2283.091691] [<ffffffff83a9afb3>] ? tty_lock_nested+0x73/0x80
> [ 2283.092779] [<ffffffff83a975cf>] mutex_lock_nested+0x3f/0x50
> [ 2283.093875] [<ffffffff83a9afb3>] tty_lock_nested+0x73/0x80
> [ 2283.094872] [<ffffffff83a9afcb>] tty_lock+0xb/0x10
> [ 2283.095443] [<ffffffff81bae880>] tty_open+0x270/0x5f0
> [ 2283.096181] [<ffffffff8127cda8>] chrdev_open+0xf8/0x1d0
> [ 2283.097054] [<ffffffff8127693c>] do_dentry_open+0x1fc/0x310
> [ 2283.098015] [<ffffffff8127ccb0>] ? cdev_put+0x20/0x20
> [ 2283.098943] [<ffffffff8127777a>] finish_open+0x4a/0x60
> [ 2283.099935] [<ffffffff81286947>] do_last+0xb87/0xe70
> [ 2283.100910] [<ffffffff812844b0>] ? link_path_walk+0x70/0x900
> [ 2283.101553] [<ffffffff81286cf2>] path_openat+0xc2/0x500
> [ 2283.102282] [<ffffffff83a9a314>] ? _raw_spin_unlock_irqrestore+0x84/0xb0
> [ 2283.103506] [<ffffffff8128716c>] do_filp_open+0x3c/0xa0
> [ 2283.104282] [<ffffffff81296c11>] ? __alloc_fd+0x1e1/0x200
> [ 2283.105278] [<ffffffff81277c0c>] do_sys_open+0x11c/0x1c0
> [ 2283.106519] [<ffffffff81277ccc>] sys_open+0x1c/0x20
> [ 2283.107241] [<ffffffff81277d01>] sys_creat+0x11/0x20
> [ 2283.107975] [<ffffffff83a9be18>] tracesys+0xe1/0xe6
prev parent reply other threads:[~2013-03-04 2:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-03 22:35 [PATCH] ircomm: release tty before sleeping potentially indefintely Sasha Levin
2013-03-03 22:47 ` David Miller
2013-03-03 23:17 ` Sasha Levin
2013-03-04 0:31 ` David Miller
2013-03-04 0:04 ` Peter Hurley
2013-03-04 0:33 ` David Miller
2013-03-04 1:06 ` Peter Hurley
2013-03-04 2:36 ` David Miller
2013-03-04 4:24 ` Peter Hurley
2013-03-05 16:09 ` [PATCH 0/4] other ircomm_tty fixes (was Re: [PATCH] ircomm: release tty before sleeping potentially indefintely) Peter Hurley
2013-03-05 16:09 ` [PATCH 1/4] net/irda: Fix port open counts Peter Hurley
2013-03-05 16:09 ` [PATCH 2/4] net/irda: Hold port lock while bumping blocked_open Peter Hurley
2013-03-05 16:09 ` [PATCH 3/4] net/irda: Use barrier to set task state Peter Hurley
2013-03-05 16:09 ` [PATCH 4/4] net/irda: Raise dtr in non-blocking open Peter Hurley
2013-03-06 4:44 ` [PATCH 0/4] other ircomm_tty fixes David Miller
2013-03-04 4:30 ` [PATCH] ircomm: release tty before sleeping potentially indefintely Peter Hurley
2013-03-04 2:23 ` Peter Hurley [this message]
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