On Wed, 2025-02-05 at 13:20 +0100, Peter Zijlstra wrote: > On Tue, Feb 04, 2025 at 08:39:52PM -0500, Rik van Riel wrote: > > > diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c > > index 6cf881a942bb..02e1f5c5bca3 100644 > > --- a/arch/x86/mm/tlb.c > > +++ b/arch/x86/mm/tlb.c > > @@ -1000,8 +1000,13 @@ static struct flush_tlb_info > > *get_flush_tlb_info(struct mm_struct *mm, > > BUG_ON(this_cpu_inc_return(flush_tlb_info_idx) != 1); > > #endif > > > > - info->start = start; > > - info->end = end; > > + /* > > + * Round the start and end addresses to the page size > > specified > > + * by the stride shift. This ensures partial pages at the > > end of > > + * a range get fully invalidated. > > + */ > > + info->start = round_down(start, 1 << > > stride_shift); > > + info->end = round_up(end, 1 << > > stride_shift); > > info->mm = mm; > > info->stride_shift = stride_shift; > > info->freed_tables = freed_tables; > > Rather than doing this; should we not fix whatever dodgy users are > feeding us non-page-aligned addresses for invalidation? > The best way to do that would probably be by adding a WARN_ON_ONCE here if the value of either start or end changed, not by merging code that will trigger kernel crashes - even if the bug is elsewhere. I would be happy to add a WARN_ON_ONCE either in a next version, or in a follow-up patch, whichever is more convenient for you. -- All Rights Reversed.
