Linux-RISC-V Archive on lore.kernel.org
 help / color / Atom feed
From: Mike Kravetz <mike.kravetz@oracle.com>
To: Dave Hansen <dave.hansen@intel.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>,
	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: Wed, 18 Mar 2020 15:52:46 -0700
Message-ID: <5aceea6a-8dc0-a44b-80c6-94511b5c75ca@oracle.com> (raw)
In-Reply-To: <831a0773-1ba6-4d72-44b9-7472123b8528@intel.com>

On 3/18/20 3:15 PM, Dave Hansen wrote:
> Hi Mike,
> 
> The series looks like a great idea to me.  One nit on the x86 bits,
> though...
> 
>> diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
>> index 5bfd5aef5378..51e6208fdeec 100644
>> --- a/arch/x86/mm/hugetlbpage.c
>> +++ b/arch/x86/mm/hugetlbpage.c
>> @@ -181,16 +181,25 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
>>  #endif /* CONFIG_HUGETLB_PAGE */
>>  
>>  #ifdef CONFIG_X86_64
>> +bool __init arch_hugetlb_valid_size(unsigned long long size)
>> +{
>> +	if (size == PMD_SIZE)
>> +		return true;
>> +	else if (size == PUD_SIZE && boot_cpu_has(X86_FEATURE_GBPAGES))
>> +		return true;
>> +	else
>> +		return false;
>> +}
> 
> I'm pretty sure it's possible to have a system without 2M/PMD page
> support.  We even have a handy-dandy comment about it in
> arch/x86/include/asm/required-features.h:
> 
> 	#ifdef CONFIG_X86_64
> 	#ifdef CONFIG_PARAVIRT
> 	/* Paravirtualized systems may not have PSE or PGE available */
> 	#define NEED_PSE        0
> 	...
> 
> I *think* you need an X86_FEATURE_PSE check here to be totally correct.
> 
> 	if (size == PMD_SIZE && cpu_feature_enabled(X86_FEATURE_PSE))
> 		return true;
> 
> BTW, I prefer cpu_feature_enabled() to boot_cpu_has() because it
> includes disabled-features checking.  I don't think any of it matters
> for these specific features, but I generally prefer it on principle.

Sounds good.  I'll incorporate those changes into a v2, unless someone
else with has a different opinion.

BTW, this patch should not really change the way the code works today.
It is mostly a movement of code.  Unless I am missing something, the
existing code will always allow setup of PMD_SIZE hugetlb pages.
-- 
Mike Kravetz


  reply index

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 [this message]
2020-03-18 23:36       ` Dave Hansen
2020-03-26 21:56         ` Mike Kravetz
2020-03-26 23:10           ` Dave Hansen
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5aceea6a-8dc0-a44b-80c6-94511b5c75ca@oracle.com \
    --to=mike.kravetz@oracle.com \
    --cc=akpm@linux-foundation.org \
    --cc=aou@eecs.berkeley.edu \
    --cc=benh@kernel.crashing.org \
    --cc=borntraeger@de.ibm.com \
    --cc=catalin.marinas@arm.com \
    --cc=corbet@lwn.net \
    --cc=dave.hansen@intel.com \
    --cc=dave.hansen@linux.intel.com \
    --cc=davem@davemloft.net \
    --cc=gor@linux.ibm.com \
    --cc=heiko.carstens@de.ibm.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=longpeng2@huawei.com \
    --cc=mingo@redhat.com \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=paulus@samba.org \
    --cc=sparclinux@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-RISC-V Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-riscv/0 linux-riscv/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-riscv linux-riscv/ https://lore.kernel.org/linux-riscv \
		linux-riscv@lists.infradead.org
	public-inbox-index linux-riscv

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-riscv


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git