From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-x244.google.com (mail-pf0-x244.google.com [IPv6:2607:f8b0:400e:c00::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 3sdQCm6fqHzDsfd for ; Tue, 20 Sep 2016 11:29:40 +1000 (AEST) Received: by mail-pf0-x244.google.com with SMTP id 21so153278pfy.1 for ; Mon, 19 Sep 2016 18:29:40 -0700 (PDT) Subject: Re: [PATCH] powerpc/mm: Update the FORCE_MAX_ZONEORDER range to enable hugetlb To: "Aneesh Kumar K.V" , benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au References: <1474306293-15390-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linuxppc-dev@lists.ozlabs.org From: Balbir Singh Message-ID: <2d14a740-2345-99d0-4d7e-ae052d416f6d@gmail.com> Date: Tue, 20 Sep 2016 11:29:33 +1000 MIME-Version: 1.0 In-Reply-To: <1474306293-15390-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 20/09/16 03:31, Aneesh Kumar K.V wrote: > For hugetlb to work with 4K page size, we need the MAX_ORDER to be more > than 13. When switching from a 64K page size to 4K linux page size using > make nconfig, we endup with a CONFIG_FORCE_MAX_ZONEORDER value of 9. > This results in 16M hugepage to be considered as a gigantic huge page > which inturn can result in failure to setup hugepages if gigantic > hugepage support is not enabled. > > This also results in kernel crash with 4K radix configuration. We > hit the below BUG_ON on radix > > kernel BUG at mm/huge_memory.c:364! > Oops: Exception in kernel mode, sig: 5 [#1] > SMP NR_CPUS=2048 NUMA PowerNV > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-rc1-00006-gbae9cc6 #1 > task: c0000000f1af8000 task.stack: c0000000f1aec000 > NIP: c000000000c5fa0c LR: c000000000c5f9d8 CTR: c000000000c5f9a4 > REGS: c0000000f1aef920 TRAP: 0700 Not tainted (4.8.0-rc1-00006-gbae9cc6) > MSR: 9000000102029033 CR: 24000844 XER: 00000000 > CFAR: c000000000c5f9e0 SOFTE: 1 > ..... > NIP [c000000000c5fa0c] hugepage_init+0x68/0x238 > LR [c000000000c5f9d8] hugepage_init+0x34/0x238 > > Fixes: a7ee539584acf ("powerpc/Kconfig: Update config option based on page size") > > Reported-by: Santhosh > Signed-off-by: Aneesh Kumar K.V > --- > arch/powerpc/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 927d2ab2ce08..792cb1768c8f 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -637,7 +637,7 @@ config FORCE_MAX_ZONEORDER > int "Maximum zone order" > range 8 9 if PPC64 && PPC_64K_PAGES > default "9" if PPC64 && PPC_64K_PAGES > - range 9 13 if PPC64 && !PPC_64K_PAGES > + range 13 13 if PPC64 && !PPC_64K_PAGES Do we need the range to be 12 13? > default "13" if PPC64 && !PPC_64K_PAGES > range 9 64 if PPC32 && PPC_16K_PAGES > default "9" if PPC32 && PPC_16K_PAGES > Otherwise Acked-by: Balbir Singh