On Sat, May 18, 2019 at 05:45:47PM +0300, Konstantin Belousov wrote:
> On Sat, May 18, 2019 at 05:38:15PM +0300, Konstantin Belousov wrote:
> > On Sat, May 18, 2019 at 10:24:36AM -0400, Mark Johnston wrote:
> > > On Sat, May 18, 2019 at 11:55:46AM +0300, Konstantin Belousov wrote:
> > > > On Sat, May 18, 2019 at 01:33:28AM -0400, Mark Johnston wrote:
> > > > > On Fri, May 17, 2019 at 10:18:57PM -0600, Rebecca Cran wrote:
> > > > > > I just updated from r346856 to r347950 and ran into a new panic,
> > > > > > caused
> > > > > > by having if_tap_load="YES" in /boot/loader.conf - because it's
> > > > > > already
> > > > > > built-in to the kernel:
> > > > >
> > > > > I think this patch should fix the panic, but I only compile-tested it.
> > > > > I considered having the logic live in preload_delete_name() instead,
> > > > > but
> > > > > the boot-time ucode code must still defer the deletion somewhat.
> > > >
> > > > Try this instead. I will revert r347931 after this landed, or could
> > > > keep
> > > > it alone.
> > >
> > > I have no strong feeling either way.
> > >
> > > > diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
> > > > index 1cf09dc5cb7..03fe8a5d096 100644
> > > > --- a/sys/amd64/amd64/machdep.c
> > > > +++ b/sys/amd64/amd64/machdep.c
> > > > @@ -1616,6 +1616,13 @@ hammer_time(u_int64_t modulep, u_int64_t
> > > > physfree)
> > > > bzero((void *)thread0.td_kstack, kstack0_sz);
> > > > physfree += kstack0_sz;
> > > >
> > > > + /*
> > > > + * Initialize enough of thread0 for delayed invalidation to
> > > > + * work very early. Rely on thread0.td_base_pri
> > > > + * zero-initialization, it is reset to PVM at proc0_init().
> > > > + */
> > > > + pmap_thread_init_invl_gen(&thread0);
> > > > +
> > >
> > > I think pmap_thread_init_invl_gen() also needs to initialize
> > > invl_gen->saved_pri to 0.
> > It is zero-initialized, same as td_base_pri. The call to
> > pmap_thread_init_invl_gen() is needed because _INVALID bit must be set,
> > which is cleared by default.
> I now think that you mean something else, that invl_gen.saved_pri must
> be set on each entry to invl_start_u(). Otherwise invl_finish_u() might
> act on the priority from the previous DI block.
That is not what I was thinking about, but I agree. thread0's saved_pri
should be zero-initialized, but I don't see how any other thread's
saved_pri is initialized - td_md is not in the zero or copy region of
the thread structure. Your patch should address this as well, but maybe
I am still missing something about how saved_pri gets initialized. The
patch looks right to me.
> diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
> index 1cf09dc5cb7..03fe8a5d096 100644
> --- a/sys/amd64/amd64/machdep.c
> +++ b/sys/amd64/amd64/machdep.c
> @@ -1616,6 +1616,13 @@ hammer_time(u_int64_t modulep, u_int64_t physfree)
> bzero((void *)thread0.td_kstack, kstack0_sz);
> physfree += kstack0_sz;
>
> + /*
> + * Initialize enough of thread0 for delayed invalidation to
> + * work very early. Rely on thread0.td_base_pri
> + * zero-initialization, it is reset to PVM at proc0_init().
> + */
> + pmap_thread_init_invl_gen(&thread0);
> +
> /*
> * make gdt memory segments
> */
> diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
> index 7997a9f65dc..89ba9da19d8 100644
> --- a/sys/amd64/amd64/pmap.c
> +++ b/sys/amd64/amd64/pmap.c
> @@ -700,16 +700,17 @@ pmap_delayed_invl_start_u(void)
> invl_gen = &td->td_md.md_invl_gen;
> PMAP_ASSERT_NOT_IN_DI();
> lock_delay_arg_init(&lda, &di_delay);
> - thread_lock(td);
> + invl_gen->saved_pri = 0;
> pri = td->td_base_pri;
> - if (pri < PVM) {
> - invl_gen->saved_pri = 0;
> - } else {
> - invl_gen->saved_pri = pri;
> - sched_prio(td, PVM);
> + if (pri > PVM) {
> + thread_lock(td);
> + pri = td->td_base_pri;
> + if (pri > PVM) {
> + invl_gen->saved_pri = pri;
> + sched_prio(td, PVM);
> + }
> + thread_unlock(td);
> }
> - thread_unlock(td);
> -
> again:
> PV_STAT(i = 0);
> for (p = &pmap_invl_gen_head;; p = prev.next) {
_______________________________________________
freebsd-current@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
