Messages in this thread | | | Date | Mon, 13 Jul 2020 18:57:43 -0700 | From | Andrei Vagin <> | Subject | Re: [PATCH v5 0/6] arm64: add the time namespace support |
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On Sat, Jul 04, 2020 at 11:40:55PM -0700, Andrei Vagin wrote: > On Wed, Jun 24, 2020 at 01:33:15AM -0700, Andrei Vagin wrote: > > Allocate the time namespace page among VVAR pages and add the logic > > to handle faults on VVAR properly. > > > > If a task belongs to a time namespace then the VVAR page which contains > > the system wide VDSO data is replaced with a namespace specific page > > which has the same layout as the VVAR page. That page has vdso_data->seq > > set to 1 to enforce the slow path and vdso_data->clock_mode set to > > VCLOCK_TIMENS to enforce the time namespace handling path. > > > > The extra check in the case that vdso_data->seq is odd, e.g. a concurrent > > update of the VDSO data is in progress, is not really affecting regular > > tasks which are not part of a time namespace as the task is spin waiting > > for the update to finish and vdso_data->seq to become even again. > > > > If a time namespace task hits that code path, it invokes the corresponding > > time getter function which retrieves the real VVAR page, reads host time > > and then adds the offset for the requested clock which is stored in the > > special VVAR page. > > > > > v2: Code cleanups suggested by Vincenzo. > > v3: add a comment in __arch_get_timens_vdso_data. > > v4: - fix an issue reported by the lkp robot. > > - vvar has the same size with/without CONFIG_TIME_NAMESPACE, but the > > timens page isn't allocated on !CONFIG_TIME_NAMESPACE. This > > simplifies criu/vdso migration between different kernel configs. > > v5: - Code cleanups suggested by Mark Rutland. > > - In vdso_join_timens, mmap_write_lock is downgraded to > > mmap_read_lock. The VMA list isn't changed there, zap_page_range > > doesn't require mmap_write_lock. > > > > Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > > Reviewed-by: Dmitry Safonov <dima@arista.com> > > Hello Will and Catalin, > > Have you had a chance to look at this patch set? I think it is ready to be > merged. Let me know if you have any questions.
*friendly ping*
If I am doing something wrong, let me know.
> > Thanks, > Andrei >
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