Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]


Groups > linux.kernel > #1617557

Re: tty crash in tty_ldisc_receive_buf()

From Benjamin Herrenschmidt <benh@kernel.crashing.org>
Newsgroups linux.kernel
Subject Re: tty crash in tty_ldisc_receive_buf()
Date 2017-04-06 09:20 +0200
Message-ID <tt9S1-5py-5@gated-at.bofh.it> (permalink)
References <tt9Il-5mv-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

Show all headers | View raw


On Thu, 2017-04-06 at 17:04 +1000, Michael Neuling wrote:
> We see this usually on boot but can also see it if we kill a getty attached to
> tty (which is then respawned by systemd).  It seems like we are flushing data to
> a tty at the same time as it's being torn down and restarted.
> 
> I did try the below patch which avoids the crash but locks up one of the CPUs. I
> guess the data never gets flushed if we say nothing is processed.
> 
> This is on powerpc but has also been reported by parisc.
> 
> I'm not at all familiar with the tty layer and looking at the locks, mutexes,
> semaphores and reference counting in there scares the hell out of me. 
> 
> If anyone has an idea, I'm happy to try a patch.

Note that we noticed one path that called reinit without the ldisc lock
held for writing, we added that, but it didn't fix the problem.

Cheers,
Ben.

Back to linux.kernel | Previous | NextPrevious in thread | Next in thread | Find similar | Unroll thread


Thread

tty crash in tty_ldisc_receive_buf() Michael Neuling <mikey@neuling.org> - 2017-04-06 09:10 +0200
  Re: tty crash in tty_ldisc_receive_buf() Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-04-06 09:20 +0200
  Re: tty crash in tty_ldisc_receive_buf() Rob Herring <robh@kernel.org> - 2017-04-06 15:30 +0200
    Re: tty crash in tty_ldisc_receive_buf() Michael Neuling <mikey@neuling.org> - 2017-04-07 02:50 +0200
    Re: tty crash in tty_ldisc_receive_buf() Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-04-07 03:10 +0200
      Re: tty crash in tty_ldisc_receive_buf() Rob Herring <robh@kernel.org> - 2017-04-07 16:10 +0200
        Re: tty crash in tty_ldisc_receive_buf() Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-04-08 01:30 +0200
  Re: tty crash in tty_ldisc_receive_buf() Wang YanQing <udknight@gmail.com> - 2017-04-07 03:30 +0200
    Re: tty crash in tty_ldisc_receive_buf() Michael Neuling <mikey@neuling.org> - 2017-04-07 04:10 +0200

csiph-web