Messages in this thread | | | Date | Tue, 23 Jun 2020 00:33:05 -0700 | From | Andrei Vagin <> | Subject | Re: [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace |
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On Fri, Jun 19, 2020 at 05:38:12PM +0200, Christian Brauner wrote: > 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()
Hmm. I am not sure that I unserstand what you mean. I think setns(nsfd, CLONE_NEWTIME) works now. For example, we use it in tools/testing/selftests/timens/timens.c. Do you mean setns(pidfd, CLONE_NEWTIME | CLONE_something)?
> 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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