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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.1 (3.54.1-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: riel@surriel.com 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: >=20 > > 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, > > =C2=A0 BUG_ON(this_cpu_inc_return(flush_tlb_info_idx) !=3D 1); > > =C2=A0#endif > > =C2=A0 > > - info->start =3D start; > > - info->end =3D 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 =3D round_down(start, 1 << > > stride_shift); > > + info->end =3D round_up(end, 1 << > > stride_shift); > > =C2=A0 info->mm =3D mm; > > =C2=A0 info->stride_shift =3D stride_shift; > > =C2=A0 info->freed_tables =3D freed_tables; >=20 > Rather than doing this; should we not fix whatever dodgy users are > feeding us non-page-aligned addresses for invalidation? >=20 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. --=20 All Rights Reversed.