From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x244.google.com (mail-pg0-x244.google.com [IPv6:2607:f8b0:400e:c05::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40bSHf3yLgzF2RN for ; Wed, 2 May 2018 15:58:05 +1000 (AEST) Received: by mail-pg0-x244.google.com with SMTP id m21-v6so9829791pgv.8 for ; Tue, 01 May 2018 22:58:05 -0700 (PDT) Date: Wed, 2 May 2018 15:57:57 +1000 From: Balbir Singh To: rashmica Cc: linuxppc-dev@lists.ozlabs.org, Michael Neuling Subject: Re: [resend] Revert "powerpc/powernv: Increase memory block size to 1GB on radix" Message-ID: <20180502155757.1a80b51e@balbir.ozlabs.ibm.com> In-Reply-To: <58c3feb3-390c-2461-2bca-5b71f8dd14df@gmail.com> References: <20180501025725.7441-1-bsingharora@gmail.com> <58c3feb3-390c-2461-2bca-5b71f8dd14df@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2 May 2018 15:10:33 +1000 rashmica 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 > > Signed-off-by: Michael Neuling > Tested-by: Rashmica Gupta 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 > > --- > > > > 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 > > >