Le 07/06/2023 à 02:56, Nicholas Piggin a écrit : > Fix an upstream powerpc bug that was discovered with a WARN_ON added in > "lazy tlb: consolidate lazy tlb mm switching": > > Switching mm and tinkering with current->active_mm should be done with > irqs disabled. There is a path where exit_lazy_flush_tlb can be called > with irqs enabled: > > exit_lazy_flush_tlb > flush_type_needed > __flush_all_mm > tlb_finish_mmu > exit_mmap > > Which results in the switching being incorrectly with irqs enabled. > > Link: https://lore.kernel.org/linuxppc-dev/87a5xcgopc.fsf@mail.lhotse/T/#m105488939d0cd9f980978ed2fdeeb89bf731e673 > Fixes: a665eec0a22e1 ("powerpc/64s/radix: Fix mm_cpumask trimming race vs k> > > I will send that fix upstream, which will end up conflicting with these. > The resolution will be to take akpm's side of the merge (with this patch). > Or drop the patch when it conflicts and I'll resend it rebased on the fix. This seems to badly conflict at the moment, is it still applicable ? Christophe > > Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> > --- > arch/powerpc/mm/book3s64/radix_tlb.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c > index 90953cf9f648..8d71fe8f5cdb 100644 > --- a/arch/powerpc/mm/book3s64/radix_tlb.c > +++ b/arch/powerpc/mm/book3s64/radix_tlb.c > @@ -795,8 +795,16 @@ void exit_lazy_flush_tlb(struct mm_struct *mm, bool always_flush) > goto out; > > if (current->active_mm == mm) { > - /* Is a kernel thread and is using mm as the lazy tlb */ > + unsigned long flags; > + > + /* > + * It is a kernel thread and is using mm as the lazy tlb, so > + * switch it to init_mm. This is not always called from IPI > + * (e.g., flush_type_needed), so must disable irqs. > + */ > + local_irq_save(flags); > kthread_end_lazy_tlb_mm(); > + local_irq_restore(flags); > } > > /*
