From: Oleg Nesterov <oleg@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
davem@davemloft.net, kuznet@ms2.inr.ac.ru, jmorris@namei.org,
yoshfuji@linux-ipv6.org, Patrick McHardy <kaber@trash.net>,
netdev@vger.kernel.org,
"linux-kernel@vger.kernel.org List"
<linux-kernel@vger.kernel.org>, Dave Jones <davej@redhat.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Subject: Re: ipv6: tunnel: hang when destroying ipv6 tunnel
Date: Sun, 1 Apr 2012 18:38:33 +0200 [thread overview]
Message-ID: <20120401163833.GA29697@redhat.com> (raw)
In-Reply-To: <CA+1xoqe1Wc_uifrKsko6hu+py9Ahz3Q0p1tRxup09jmh2NZ1rw@mail.gmail.com>
On 04/01, Sasha Levin wrote:
>
> >> It would be nice to know what sysrq-t says, in particular the trace
> >> of khelper thread is interesting.
> >
> > Sure, I'll get one when it happens again.
>
> So here's the stack of the usermode thread:
Great, thanks, this is even better than khelper's trace,
> [ 336.614015] [<ffffffff826a8e54>] schedule+0x24/0x70
> [ 336.614015] [<ffffffff825fd66d>] p9_client_rpc+0x13d/0x360
> [ 336.614015] [<ffffffff810d7850>] ? wake_up_bit+0x40/0x40
> [ 336.614015] [<ffffffff810e3671>] ? get_parent_ip+0x11/0x50
> [ 336.614015] [<ffffffff810e399d>] ? sub_preempt_count+0x9d/0xd0
> [ 336.614015] [<ffffffff825ff5ff>] p9_client_walk+0x8f/0x220
> [ 336.614015] [<ffffffff815a8e3b>] v9fs_vfs_lookup+0xab/0x1c0
> [ 336.614015] [<ffffffff811ee0c0>] d_alloc_and_lookup+0x40/0x80
> [ 336.614015] [<ffffffff811fdea0>] ? d_lookup+0x30/0x50
> [ 336.614015] [<ffffffff811f0aea>] do_lookup+0x28a/0x3b0
> [ 336.614015] [<ffffffff817c9117>] ? security_inode_permission+0x17/0x20
> [ 336.614015] [<ffffffff811f1c07>] link_path_walk+0x167/0x420
> [ 336.614015] [<ffffffff811ee630>] ? generic_readlink+0xb0/0xb0
> [ 336.614015] [<ffffffff81896d88>] ? __raw_spin_lock_init+0x38/0x70
> [ 336.614015] [<ffffffff811f24da>] path_openat+0xba/0x500
> [ 336.614015] [<ffffffff81057253>] ? sched_clock+0x13/0x20
> [ 336.614015] [<ffffffff810ed805>] ? sched_clock_local+0x25/0x90
> [ 336.614015] [<ffffffff810ed940>] ? sched_clock_cpu+0xd0/0x120
> [ 336.614015] [<ffffffff811f2a34>] do_filp_open+0x44/0xa0
> [ 336.614015] [<ffffffff81119acd>] ? __lock_release+0x8d/0x1d0
> [ 336.614015] [<ffffffff810e3671>] ? get_parent_ip+0x11/0x50
> [ 336.614015] [<ffffffff810e399d>] ? sub_preempt_count+0x9d/0xd0
> [ 336.614015] [<ffffffff826aa7f0>] ? _raw_spin_unlock+0x30/0x60
> [ 336.614015] [<ffffffff811ea74d>] open_exec+0x2d/0xf0
> [ 336.614015] [<ffffffff811eb888>] do_execve_common+0x128/0x320
> [ 336.614015] [<ffffffff811ebb05>] do_execve+0x35/0x40
> [ 336.614015] [<ffffffff810589e5>] sys_execve+0x45/0x70
> [ 336.614015] [<ffffffff826acc28>] kernel_execve+0x68/0xd0
> [ 336.614015] [<ffffffff810cd6a6>] ? ____call_usermodehelper+0xf6/0x130
> [ 336.614015] [<ffffffff810cd6f9>] call_helper+0x19/0x20
> [ 336.614015] [<ffffffff826acbb4>] kernel_thread_helper+0x4/0x10
> [ 336.614015] [<ffffffff810e3f80>] ? finish_task_switch+0x80/0x110
> [ 336.614015] [<ffffffff826aaeb4>] ? retint_restore_args+0x13/0x13
> [ 336.614015] [<ffffffff810cd6e0>] ? ____call_usermodehelper+0x130/0x130
> [ 336.614015] [<ffffffff826acbb0>] ? gs_change+0x13/0x13
>
> While it seems that 9p is the culprit, I have to point out that this
> bug is easily reproducible, and it happens each time due to a
> call_usermode_helper() call. Other than that 9p behaves perfectly and
> I'd assume that I'd be seeing other things break besides
> call_usermode_helper() related ones.
Of course I do not know what happens, but at least this obviously
explains why UMH_WAIT_EXEC hangs, I think call_usermodehelper_exec()
itself is innocent.
Oleg.
prev parent reply other threads:[~2012-04-01 17:18 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-31 17:51 ipv6: tunnel: hang when destroying ipv6 tunnel Sasha Levin
2012-03-31 20:59 ` Eric Dumazet
2012-03-31 21:34 ` Oleg Nesterov
2012-03-31 21:43 ` Sasha Levin
2012-03-31 23:26 ` Sasha Levin
2012-04-01 3:21 ` Tetsuo Handa
2012-04-01 17:33 ` Sasha Levin
2012-04-05 14:29 ` Tetsuo Handa
2012-04-05 14:34 ` Tetsuo Handa
2012-04-06 11:44 ` Tetsuo Handa
2012-04-06 18:09 ` Jim Garlick
2012-04-07 0:06 ` Tetsuo Handa
2012-04-11 12:20 ` Sasha Levin
2012-04-01 5:07 ` Eric Dumazet
2012-04-01 16:38 ` Oleg Nesterov [this message]
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=20120401163833.GA29697@redhat.com \
--to=oleg@redhat.com \
--cc=davej@redhat.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=jmorris@namei.org \
--cc=kaber@trash.net \
--cc=kuznet@ms2.inr.ac.ru \
--cc=levinsasha928@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=penguin-kernel@i-love.sakura.ne.jp \
--cc=yoshfuji@linux-ipv6.org \
/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).