Messages in this thread | | | Date | Fri, 19 Jun 2020 17:38:12 +0200 | From | Christian Brauner <> | Subject | Re: [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace |
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On Tue, Jun 16, 2020 at 12:55:41AM -0700, Andrei Vagin wrote: > The VVAR page layout depends on whether a task belongs to the root or > non-root time namespace. Whenever a task changes its namespace, the VVAR > page tables are cleared and then they will be re-faulted with a > corresponding layout. > > Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > Reviewed-by: Dmitry Safonov <dima@arista.com> > Signed-off-by: Andrei Vagin <avagin@gmail.com> > --- > arch/arm64/kernel/vdso.c | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index b0aec4e8c9b4..df4bb736d28a 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -125,6 +125,38 @@ static int __vdso_init(enum vdso_abi abi) > return 0; > } > > +#ifdef CONFIG_TIME_NS > +/* > + * The vvar page layout depends on whether a task belongs to the root or > + * non-root time namespace. Whenever a task changes its namespace, the VVAR > + * page tables are cleared and then they will re-faulted with a > + * corresponding layout. > + * See also the comment near timens_setup_vdso_data() for details. > + */ > +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) > +{ > + struct mm_struct *mm = task->mm; > + struct vm_area_struct *vma; > + > + if (mmap_write_lock_killable(mm)) > + return -EINTR;
Hey,
Just a heads-up I'm about to plumb CLONE_NEWTIME support into setns() which would mean that vdso_join_timens() ould not be allowed to fail anymore to make it easy to switch to multiple namespaces atomically. So this would probably need to be changed to mmap_write_lock() which I've already brought up upstream: https://lore.kernel.org/lkml/20200611110221.pgd3r5qkjrjmfqa2@wittgenstein/ (Assuming that people agree. I just sent the series and most people here are Cced.)
Thanks! Christian
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