From: Dave Hansen <dave.hansen@intel.com>
To: Mike Kravetz <mike.kravetz@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, sparclinux@vger.kernel.org,
linux-doc@vger.kernel.org
Cc: Albert Ou <aou@eecs.berkeley.edu>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vasily Gorbik <gor@linux.ibm.com>,
Jonathan Corbet <corbet@lwn.net>,
Catalin Marinas <catalin.marinas@arm.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"Shutemov, Kirill" <kirill.shutemov@intel.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Ingo Molnar <mingo@redhat.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Paul Mackerras <paulus@samba.org>,
Thomas Gleixner <tglx@linutronix.de>,
Longpeng <longpeng2@huawei.com>, Will Deacon <will@kernel.org>,
"David S.Miller" <davem@davemloft.net>
Subject: Re: [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size
Date: Thu, 26 Mar 2020 16:10:56 -0700 [thread overview]
Message-ID: <ae80063f-cef8-3141-3c6b-9130def5396a@intel.com> (raw)
In-Reply-To: <530e6e11-ad1a-55bc-e61e-9da6eb7fea21@oracle.com>
On 3/26/20 2:56 PM, Mike Kravetz wrote:
> Perhaps it would be best to check hugepages_supported() when parsing
> hugetlb command line options. If not enabled, throw an error. This
> will be much easier to do after moving all command line parsing to
> arch independent code.
Yeah, that sounds sane.
> Is that a sufficient way to address this concern? I think it is a good
> change in any case.
(Thanks to Kirill for pointing this out.)
So, it turns out the x86 huge page enumeration is totally buggered.
X86_FEATURE_PSE is actually meaningless on 64-bit (and 32-bit PAE). All
CPUs architecturally support 2MB pages regardless of X86_FEATURE_PSE and
the state of CR4.PSE.
So, on x86_64 at least, hugepages_supported() should *always* return 1.
1GB page support can continue to be dependent on X86_FEATURE_GBPAGES.
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next prev parent reply other threads:[~2020-03-26 23:11 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 22:06 [PATCH 0/4] Clean up hugetlb boot command line processing Mike Kravetz
2020-03-18 22:06 ` [PATCH 1/4] hugetlbfs: add arch_hugetlb_valid_size Mike Kravetz
2020-03-18 22:09 ` Will Deacon
2020-03-18 22:38 ` Mike Kravetz
2020-03-18 22:15 ` Dave Hansen
2020-03-18 22:52 ` Mike Kravetz
2020-03-18 23:36 ` Dave Hansen
2020-03-26 21:56 ` Mike Kravetz
2020-03-26 23:10 ` Dave Hansen [this message]
2020-03-25 2:58 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2020-03-25 9:38 ` Christian Borntraeger
2020-03-19 0:48 ` kbuild test robot
2020-03-19 1:39 ` kbuild test robot
2020-03-19 7:00 ` Christophe Leroy
2020-03-19 18:17 ` Mike Kravetz
2020-03-23 23:43 ` Mina Almasry
2020-03-18 22:06 ` [PATCH 2/4] hugetlbfs: move hugepagesz= parsing to arch independent code Mike Kravetz
2020-03-19 7:04 ` Christophe Leroy
2020-03-19 17:00 ` Mike Kravetz
2020-03-23 23:56 ` Mina Almasry
2020-03-18 22:06 ` [PATCH 3/4] hugetlbfs: remove hugetlb_add_hstate() warning for existing hstate Mike Kravetz
2020-03-24 0:01 ` Mina Almasry
2020-03-24 0:16 ` Mike Kravetz
2020-03-24 0:23 ` Mina Almasry
2020-03-18 22:06 ` [PATCH 4/4] hugetlbfs: clean up command line processing Mike Kravetz
2020-03-19 0:20 ` Randy Dunlap
2020-03-19 2:42 ` Mike Kravetz
2020-03-24 0:43 ` Mina Almasry
2020-03-24 3:47 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2020-03-25 1:12 ` Mike Kravetz
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