Hi Dmitry, On Wed, Aug 29, 2018 at 03:23:49AM +0100, Dmitry Safonov wrote: > Two fixes for potential and real issues. > Looks worth to have in stables as we've hit it on v4.9 stable. > And for linux-next - adding lockdep asserts for line discipline changing > code, verifying that write ldisc sem will be held forthwith. > > I couldn't verify that holding write lock fixes the issue as we've hit > it only once and I've failed in reproducing it. > But searching in lkml, Cc'ing here people who probably had the same > crash (and in hope someone of them could give tested-by): > And thanks a lot for your work on fixing these issues! I've added Nathan (and centos-virt) to CC, because earlier Nathan was able to reliably trigger ldisc related kernel crash in Xen dom0 when running Linux 4.9 kernel, which seems similar to what your patch 2/4 is trying to fix. Nathan's kernel crash report: https://lists.centos.org/pipermail/centos-virt/2017-August/005610.html Example ldisc kernel crash BUG in "n_tty_receive_buf_common": https://lists.centos.org/pipermail/centos-virt/attachments/20170823/45493276/attachment.txt CentOS bug: https://bugs.centos.org/view.php?id=13713 Thanks, -- Pasi > Cc: Daniel Axtens <dja@xxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Michael Neuling <mikey@xxxxxxxxxxx> > Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Cc: Pasi Kärkkäinen <pasik@xxxxxx> > Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> > Cc: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx> > Cc: Tan Xiaojun <tanxiaojun@xxxxxxxxxx> > (please, ignore if I Cc'ed you mistakenly) > > Dmitry Safonov (4): > tty: Drop tty->count on tty_reopen() failure > tty: Hold tty_ldisc_lock() during tty_reopen() > tty: Lock tty pair in tty_init_dev() > tty/lockdep: Add ldisc_sem asserts > > drivers/tty/tty_io.c | 21 +++++++++++++++------ > drivers/tty/tty_ldisc.c | 12 ++++++++---- > include/linux/tty.h | 4 ++++ > 3 files changed, 27 insertions(+), 10 deletions(-) > > -- > 2.13.6 >
