From: Dmitry Safonov <dima@arista.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: linux-kernel@vger.kernel.org,
"Dmitry Safonov" <0x7f454c46@gmail.com>,
"Daniel Axtens" <dja@axtens.net>,
"Dmitry Vyukov" <dvyukov@google.com>,
"Mark Rutland" <mark.rutland@arm.com>,
"Michael Neuling" <mikey@neuling.org>,
"Nathan March" <nathan@gt.net>, "Pasi Kärkkäinen" <pasik@iki.fi>,
"Peter Hurley" <peter@hurleysoftware.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Rong, Chen" <rong.a.chen@intel.com>,
"Sergey Senozhatsky" <sergey.senozhatsky.work@gmail.com>,
"Tan Xiaojun" <tanxiaojun@huawei.com>,
"Tetsuo Handa" <penguin-kernel@I-love.SAKURA.ne.jp>,
stable@vger.kernel.org,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Jiri Slaby" <jslaby@suse.com>, "Jiri Slaby" <jslaby@suse.cz>,
syzbot+3aa9784721dfb90e984d@syzkaller.appspotmail.com
Subject: Re: [PATCHv5 0/7] tty: Hold write ldisc sem in tty_reopen()
Date: Wed, 19 Sep 2018 21:21:52 +0100 [thread overview]
Message-ID: <1537388512.21380.44.camel@arista.com> (raw)
In-Reply-To: <alpine.LRH.2.02.1809191602230.16174@file01.intranet.prod.int.rdu2.redhat.com>
On Wed, 2018-09-19 at 16:03 -0400, Mikulas Patocka wrote:
>
> On Wed, 19 Sep 2018, Dmitry Safonov wrote:
> > Thanks much for the testing, Mikulas.
> > Could you try to bisect which of the patches causes it?
> > The most important are 1,2,3 - probably, one of them caused it..
> > I'll stare a bit into the code.
>
> The patch 3 causes it.
>
> The hangs during reboot take either 80 seconds, 3 minutes or 3:25.
Thanks much for that again.
Any chance you have sysrq enabled and could print: locks held in system
and kernel backtraces for applications?
I suppose, userspace hangs in n_tty_receive_buf_common(), which is
better of cause than null-ptr dereference, but I believe we can improve
it by stopping a reader earlier if there is any writer pending.
--
Thanks,
Dmitry
next prev parent reply other threads:[~2018-09-19 20:21 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-17 23:52 [PATCHv5 0/7] tty: Hold write ldisc sem in tty_reopen() Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 1/7] tty: Drop tty->count on tty_reopen() failure Dmitry Safonov
2018-09-18 13:41 ` Greg Kroah-Hartman
2018-09-18 14:15 ` Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 2/7] tty/ldsem: Wake up readers after timed out down_write() Dmitry Safonov
2018-09-18 13:43 ` Greg Kroah-Hartman
2018-09-18 14:12 ` Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 3/7] tty: Hold tty_ldisc_lock() during tty_reopen() Dmitry Safonov
2018-09-18 13:47 ` Greg Kroah-Hartman
2018-09-18 14:19 ` Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 4/7] tty: Simplify tty->count math in tty_reopen() Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 5/7] tty/ldsem: Convert to regular lockdep annotations Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 6/7] tty/ldsem: Add lockdep asserts for ldisc_sem Dmitry Safonov
2018-09-18 13:49 ` Greg Kroah-Hartman
2018-09-18 14:21 ` Dmitry Safonov
2018-09-17 23:52 ` [PATCHv5 7/7] tty/ldsem: Decrement wait_readers on timeouted down_read() Dmitry Safonov
2018-09-19 16:56 ` [PATCHv5 0/7] tty: Hold write ldisc sem in tty_reopen() Mikulas Patocka
2018-09-19 17:35 ` Mikulas Patocka
2018-09-19 17:45 ` Dmitry Safonov
2018-09-19 20:03 ` Mikulas Patocka
2018-09-19 20:21 ` Dmitry Safonov [this message]
2018-09-20 14:25 ` Mikulas Patocka
2018-10-15 13:37 ` Pasi Kärkkäinen
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=1537388512.21380.44.camel@arista.com \
--to=dima@arista.com \
--cc=0x7f454c46@gmail.com \
--cc=dja@axtens.net \
--cc=dvyukov@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=jslaby@suse.com \
--cc=jslaby@suse.cz \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mikey@neuling.org \
--cc=mpatocka@redhat.com \
--cc=nathan@gt.net \
--cc=pasik@iki.fi \
--cc=penguin-kernel@I-love.SAKURA.ne.jp \
--cc=peter@hurleysoftware.com \
--cc=peterz@infradead.org \
--cc=rong.a.chen@intel.com \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=stable@vger.kernel.org \
--cc=syzbot+3aa9784721dfb90e984d@syzkaller.appspotmail.com \
--cc=tanxiaojun@huawei.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