On So 29-04-06 23:57:21, Andrew Morton wrote:
> Shaohua Li <[email protected]> wrote:
> >
> > On Sun, 2006-04-30 at 06:45 +0000, Pavel Machek wrote:
> > > Hi!
> > >
> > > > flush_tlb_all uses on_each_cpu, which will disable/enable interrupt.
> > > > In suspend/resume time, this will make interrupt wrongly enabled.
> > >
> > > > diff -puN arch/i386/mm/init.c~flush_tlb_all_check arch/i386/mm/init.c
> > > > --- linux-2.6.17-rc3/arch/i386/mm/init.c~flush_tlb_all_check 2006-04-29 08:47:05.000000000 +0800
> > > > +++ linux-2.6.17-rc3-root/arch/i386/mm/init.c 2006-04-29 08:48:15.000000000 +0800
> > > > @@ -420,7 +420,10 @@ void zap_low_mappings (void)
> > > > #else
> > > > set_pgd(swapper_pg_dir+i, __pgd(0));
> > > > #endif
> > > > - flush_tlb_all();
> > > > + if (cpus_weight(cpu_online_map) == 1)
> > > > + local_flush_tlb();
> > > > + else
> > > > + flush_tlb_all();
> > > > }
> > > >
> > >
> > > Either it is okay to enable interrupts here -> unneccessary and ugly
> > > test, or it is not, and then we are broken in SMP case.
> > It's not broken in SMP case, APs are offlined here in suspend/resume.
> >
>
> In which case, how's about this?
Certainly better, I'd say.
> @@ -420,7 +421,14 @@ void zap_low_mappings (void)
> #else
> set_pgd(swapper_pg_dir+i, __pgd(0));
> #endif
> - if (cpus_weight(cpu_online_map) == 1)
> + /*
> + * We can be called at suspend/resume time, with local interrupts
> + * disabled. But flush_tlb_all() requires that local interrupts be
> + * enabled.
> + *
> + * Happily, the APs are not yet started, so we can use local_flush_tlb() * in that case
> + */
> + if (num_online_cpus() == 1)
> local_flush_tlb();
> else
> flush_tlb_all();
But this still scares. It means calling convention is "may enable
interrupts with >1 cpu, may not with == 1 cpu".
Pavel
--
Thanks for all the (sleeping) penguins.
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