On Fri, Jul 07, 2017 at 12:51:05PM +0200, Martin Pieuchot wrote:
> On 06/07/17(Thu) 21:18, Juan Francisco Cantero Hurtado wrote:
> > On Thu, Jul 06, 2017 at 08:29:39AM -0600, Aaron Bieber wrote:
> > > Hola,
> > >
> > > For roughly a week I have been able to reliably produce panics on
> > > amd64 (virtual machine and physical machine) using disk IO heavy
> > > applications (gitea, syncthing).
> > >
> > > Unfortunately on the physical machine - the one I can reliably panic
> > > within < 1 minute - I don't have a serial console, so here are links
> > > to photos:
> > >
> > > https://goo.gl/photos/Z8g225UXXpCXQpGcA
> > > mirror/google averse: https://deftly.net/panic-2017-07-06/
> > >
> > > Also with machdep.forceukbd=1, once I ran `mach ddbcpu 0`, every
> > > subsequent key press puked out an "splassert" line, I attempted to run
> > > a "trace" again, but things seemed to be completely locked up after that.
> >
> > I'm seeing the same panic but I can't run ddb. Also with syncthing.
>
> Here's a fix. The problem certainly comes from a contented NET_LOCK()
> which means that we now have a sleeping point where we're not allowed
> to sleep.
>
> Diff below revert the solock()/sounlock() dances in the kqueue filters,
> let me know if it works for you.
The kernel doesn't panic with your patch. Thanks!.
>
> Index: kern/uipc_socket.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/uipc_socket.c,v
> retrieving revision 1.192
> diff -u -p -r1.192 uipc_socket.c
> --- kern/uipc_socket.c 4 Jul 2017 12:58:32 -0000 1.192
> +++ kern/uipc_socket.c 7 Jul 2017 10:46:40 -0000
> @@ -1998,10 +1998,8 @@ int
> filt_sowrite(struct knote *kn, long hint)
> {
> struct socket *so = kn->kn_fp->f_data;
> - int s, rv;
> + int rv;
>
> - if (!(hint & NOTE_SUBMIT))
> - s = solock(so);
> kn->kn_data = sbspace(so, &so->so_snd);
> if (so->so_state & SS_CANTSENDMORE) {
> kn->kn_flags |= EV_EOF;
> @@ -2017,8 +2015,6 @@ filt_sowrite(struct knote *kn, long hint
> } else {
> rv = (kn->kn_data >= so->so_snd.sb_lowat);
> }
> - if (!(hint & NOTE_SUBMIT))
> - sounlock(s);
>
> return (rv);
> }
> @@ -2027,13 +2023,8 @@ int
> filt_solisten(struct knote *kn, long hint)
> {
> struct socket *so = kn->kn_fp->f_data;
> - int s;
>
> - if (!(hint & NOTE_SUBMIT))
> - s = solock(so);
> kn->kn_data = so->so_qlen;
> - if (!(hint & NOTE_SUBMIT))
> - sounlock(s);
>
> return (kn->kn_data != 0);
> }
> Index: miscfs/fifofs/fifo_vnops.c
> ===================================================================
> RCS file: /cvs/src/sys/miscfs/fifofs/fifo_vnops.c,v
> retrieving revision 1.56
> diff -u -p -r1.56 fifo_vnops.c
> --- miscfs/fifofs/fifo_vnops.c 3 Jul 2017 08:31:39 -0000 1.56
> +++ miscfs/fifofs/fifo_vnops.c 7 Jul 2017 10:46:57 -0000
> @@ -531,10 +531,8 @@ int
> filt_fiforead(struct knote *kn, long hint)
> {
> struct socket *so = (struct socket *)kn->kn_hook;
> - int s, rv;
> + int rv;
>
> - if (!(hint & NOTE_SUBMIT))
> - s = solock(so);
> kn->kn_data = so->so_rcv.sb_cc;
> if (so->so_state & SS_CANTRCVMORE) {
> kn->kn_flags |= EV_EOF;
> @@ -543,8 +541,6 @@ filt_fiforead(struct knote *kn, long hin
> kn->kn_flags &= ~EV_EOF;
> rv = (kn->kn_data > 0);
> }
> - if (!(hint & NOTE_SUBMIT))
> - sounlock(s);
>
> return (rv);
> }
> @@ -563,10 +559,8 @@ int
> filt_fifowrite(struct knote *kn, long hint)
> {
> struct socket *so = (struct socket *)kn->kn_hook;
> - int s, rv;
> + int rv;
>
> - if (!(hint & NOTE_SUBMIT))
> - s = solock(so);
> kn->kn_data = sbspace(so, &so->so_snd);
> if (so->so_state & SS_CANTSENDMORE) {
> kn->kn_flags |= EV_EOF;
> @@ -575,8 +569,6 @@ filt_fifowrite(struct knote *kn, long hi
> kn->kn_flags &= ~EV_EOF;
> rv = (kn->kn_data >= so->so_snd.sb_lowat);
> }
> - if (!(hint & NOTE_SUBMIT))
> - sounlock(s);
>
> return (rv);
> }
> Index: sys/socketvar.h
> ===================================================================
> RCS file: /cvs/src/sys/sys/socketvar.h,v
> retrieving revision 1.72
> diff -u -p -r1.72 socketvar.h
> --- sys/socketvar.h 4 Jul 2017 12:58:32 -0000 1.72
> +++ sys/socketvar.h 7 Jul 2017 10:46:32 -0000
> @@ -186,7 +186,10 @@ static inline long
> sbspace(struct socket *so, struct sockbuf *sb)
> {
> KASSERT(sb == &so->so_rcv || sb == &so->so_snd);
> +#if 0
> + /* XXXSMP kqueue_scan() calling filt_sowrite() cannot sleep. */
> soassertlocked(so);
> +#endif
> return lmin(sb->sb_hiwat - sb->sb_cc, sb->sb_mbmax - sb->sb_mbcnt);
> }
>
>
--
Juan Francisco Cantero Hurtado http://juanfra.info
