LOR between allproc <-> ufs

[Yamagi Burmeister]

Hello,
I think I'm a little bit late to the party. As always in this
situations the panic message wasn't included into the dump, the
unread portion of the kernel message buffer is empty.

I've crashed the system again and got two messages:
 - panic: sleeping thread
 - panic: thread with borrowed priority returning to userland

Likely another incarnation of the panic in Peter Holms kostik886.txt.
Can I do something more to help with this?

Regards,
Yamagi

On Fri, 27 May 2016 17:10:16 +0300
Konstantin Belousov <kostikbel at gmail.com> wrote:

> On Fri, May 27, 2016 at 03:37:05PM +0200, Yamagi Burmeister wrote:
> > On Thu, 26 May 2016 18:58:44 +0300
> > Konstantin Belousov <kostikbel at gmail.com> wrote:
> > 
> > > Completely untested patch is below.  I do not think that this LOR
> > > can be reproduced at will.  E.g. you need to record the order
> > > in witness by unmounting some filesystem mounted on a directory
> > > on UFS mount.  Then, the chances must be that it was the last
> > > reference on the vmspace, or that there were deferred vnode entry.
> > 
> > With this patch the system panics as soon there's some load on the
> > filesystem. Maybe only when several processes accessing the same
> > mountpoint, but I'm not sure. For example 'make -j24 buildkernel'
> > crashes the system nearly instantly.
> >     at /usr/src/sys/kern/kern_shutdown.c:777
> > #11 0xffffffff809b5aeb in witness_warn (flags=<value optimized out>, lock=<value optimized out>, 
> >     fmt=<value optimized out>) at /usr/src/sys/kern/subr_witness.c:1757
> > #12 0xffffffff809aa0a8 in userret (td=0xfffff800264c6960, frame=<value optimized out>)
> >     at /usr/src/sys/kern/subr_trap.c:157
> > #13 0xffffffff80d78151 in amd64_syscall (td=0xfffff800264c6960, traced=<value optimized out>)
> >     at subr_syscall.c:185
> 
> This is an assert about some lock leak.  Most useful is verbatim
> panic message with all surrounding kernel printouts.  I do not even need
> the backtrace.


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