On Wed, 2 May 2018 15:10:33 +1000
rashmica <rashmic...@gmail.com> wrote:
> Tested hot-unplugging dimm device on radix guest on p9 host with KVM.
>
>
> On 01/05/18 12:57, Balbir Singh wrote:
> > This commit was a stop-gap to prevent crashes on hotunplug, caused by
> > the mismatch between the 1G mappings used for the linear mapping and the
> > memory block size. Those issues are now resolved because we split the
> > linear mapping at hotunplug time if necessary, as implemented in commit
> > 4dd5f8a99e79 ("powerpc/mm/radix: Split linear mapping on hot-unplug").
> >
> > Signed-off-by: Balbir Singh <bsinghar...@gmail.com>
> > Signed-off-by: Michael Neuling <mi...@neuling.org>
> Tested-by: Rashmica Gupta <rashmic...@gmail.com>
I tested the following:
a. memtrace - enable a region smaller than 1G, which split the mappings
as expected.
b. Checked linear mapping is 1G and not impacted by the revert
c. I can hotplug sizes less than 1G via the probe method
Tested-by: Balbir Singh <bsinghar...@gmail.com>
> > ---
> >
> > Resend with a newer commit message grabbed from an email sent by mpe.
> >
> > arch/powerpc/platforms/powernv/setup.c | 10 +---------
> > 1 file changed, 1 insertion(+), 9 deletions(-)
> >
> > diff --git a/arch/powerpc/platforms/powernv/setup.c
> > b/arch/powerpc/platforms/powernv/setup.c
> > index ef8c9ce53a61..fa63d3fff14c 100644
> > --- a/arch/powerpc/platforms/powernv/setup.c
> > +++ b/arch/powerpc/platforms/powernv/setup.c
> > @@ -356,15 +356,7 @@ static void pnv_kexec_cpu_down(int crash_shutdown, int
> > secondary)
> > #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
> > static unsigned long pnv_memory_block_size(void)
> > {
> > - /*
> > - * We map the kernel linear region with 1GB large pages on radix. For
> > - * memory hot unplug to work our memory block size must be at least
> > - * this size.
> > - */
> > - if (radix_enabled())
> > - return 1UL * 1024 * 1024 * 1024;
> > - else
> > - return 256UL * 1024 * 1024;
> > + return 256UL * 1024 * 1024;
> > }
> > #endif
> >
>
