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From: Dave Hansen <dave.hansen@intel.com>
To: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
	Michal Hocko <mhocko@suse.cz>, Rik van Riel <riel@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andy Lutomirski <luto@amacapital.net>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Bob Liu <lliubbo@gmail.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Gleb Natapov <gleb@kernel.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	Hugh Dickins <hughd@google.com>, Ingo Molnar <mingo@kernel.org>,
	Jianyu Zhan <nasa4836@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Konstantin Weitz <konstantin.weitz@gmail.com>,
	kvm@vger.kernel.org, linux390@de.ibm.com,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Martin
Subject: Re: [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag
Date: Sat, 18 Oct 2014 09:28:17 -0700	[thread overview]
Message-ID: <54429521.80402@intel.com> (raw)
In-Reply-To: <20141018164928.2341415f@BR9TG4T3.de.ibm.com>

On 10/18/2014 07:49 AM, Dominik Dingel wrote:
> On Fri, 17 Oct 2014 15:04:21 -0700
> Dave Hansen <dave.hansen@intel.com> wrote:
>> Is there ever a time where the VMAs under an mm have mixed VM_NOZEROPAGE
>> status?  Reading the patches, it _looks_ like it might be an all or
>> nothing thing.
> 
> Currently it is an all or nothing thing, but for a future change we might want to just
> tag the guest memory instead of the complete user address space.

I think it's a bad idea to reserve a flag for potential future use.  If
you _need_ it in the future, let's have the discussion then.  For now, I
think it should probably just be stored in the mm somewhere.

>> Full disclosure: I've got an x86-specific feature I want to steal a flag
>> for.  Maybe we should just define another VM_ARCH bit.
>>
> 
> So you think of something like:
> 
> #if defined(CONFIG_S390)
> # define VM_NOZEROPAGE	VM_ARCH_1
> #endif
> 
> #ifndef VM_NOZEROPAGE
> # define VM_NOZEROPAGE	VM_NONE
> #endif
> 
> right?

Yeah, something like that.

--
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WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
	Michal Hocko <mhocko@suse.cz>, Rik van Riel <riel@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andy Lutomirski <luto@amacapital.net>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Bob Liu <lliubbo@gmail.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Gleb Natapov <gleb@kernel.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	Hugh Dickins <hughd@google.com>, Ingo Molnar <mingo@kernel.org>,
	Jianyu Zhan <nasa4836@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Konstantin Weitz <konstantin.weitz@gmail.com>,
	kvm@vger.kernel.org, linux390@de.ibm.com,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Sasha Levin <sasha.levin@oracle.com>
Subject: Re: [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag
Date: Sat, 18 Oct 2014 09:28:17 -0700	[thread overview]
Message-ID: <54429521.80402@intel.com> (raw)
In-Reply-To: <20141018164928.2341415f@BR9TG4T3.de.ibm.com>

On 10/18/2014 07:49 AM, Dominik Dingel wrote:
> On Fri, 17 Oct 2014 15:04:21 -0700
> Dave Hansen <dave.hansen@intel.com> wrote:
>> Is there ever a time where the VMAs under an mm have mixed VM_NOZEROPAGE
>> status?  Reading the patches, it _looks_ like it might be an all or
>> nothing thing.
> 
> Currently it is an all or nothing thing, but for a future change we might want to just
> tag the guest memory instead of the complete user address space.

I think it's a bad idea to reserve a flag for potential future use.  If
you _need_ it in the future, let's have the discussion then.  For now, I
think it should probably just be stored in the mm somewhere.

>> Full disclosure: I've got an x86-specific feature I want to steal a flag
>> for.  Maybe we should just define another VM_ARCH bit.
>>
> 
> So you think of something like:
> 
> #if defined(CONFIG_S390)
> # define VM_NOZEROPAGE	VM_ARCH_1
> #endif
> 
> #ifndef VM_NOZEROPAGE
> # define VM_NOZEROPAGE	VM_NONE
> #endif
> 
> right?

Yeah, something like that.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>,
	Michal Hocko <mhocko@suse.cz>, Rik van Riel <riel@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andy Lutomirski <luto@amacapital.net>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Bob Liu <lliubbo@gmail.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Cornelia Huck <cornelia.huck@de.ibm.com>,
	Gleb Natapov <gleb@kernel.org>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	"H. Peter Anvin" <hpa@linux.intel.com>,
	Hugh Dickins <hughd@google.com>, Ingo Molnar <mingo@kernel.org>,
	Jianyu Zhan <nasa4836@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Konstantin Weitz <konstantin.weitz@gmail.com>,
	kvm@vger.kernel.org, linux390@de.ibm.com,
	linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Sasha Levin <sasha.levin@oracle.com>
Subject: Re: [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag
Date: Sat, 18 Oct 2014 09:28:17 -0700	[thread overview]
Message-ID: <54429521.80402@intel.com> (raw)
In-Reply-To: <20141018164928.2341415f@BR9TG4T3.de.ibm.com>

On 10/18/2014 07:49 AM, Dominik Dingel wrote:
> On Fri, 17 Oct 2014 15:04:21 -0700
> Dave Hansen <dave.hansen@intel.com> wrote:
>> Is there ever a time where the VMAs under an mm have mixed VM_NOZEROPAGE
>> status?  Reading the patches, it _looks_ like it might be an all or
>> nothing thing.
> 
> Currently it is an all or nothing thing, but for a future change we might want to just
> tag the guest memory instead of the complete user address space.

I think it's a bad idea to reserve a flag for potential future use.  If
you _need_ it in the future, let's have the discussion then.  For now, I
think it should probably just be stored in the mm somewhere.

>> Full disclosure: I've got an x86-specific feature I want to steal a flag
>> for.  Maybe we should just define another VM_ARCH bit.
>>
> 
> So you think of something like:
> 
> #if defined(CONFIG_S390)
> # define VM_NOZEROPAGE	VM_ARCH_1
> #endif
> 
> #ifndef VM_NOZEROPAGE
> # define VM_NOZEROPAGE	VM_NONE
> #endif
> 
> right?

Yeah, something like that.


  reply	other threads:[~2014-10-18 16:28 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-17 14:09 [PATCH 0/4] mm: new flag to forbid zero page mappings for a vma Dominik Dingel
2014-10-17 14:09 ` Dominik Dingel
2014-10-17 14:09 ` Dominik Dingel
2014-10-17 14:09 ` Dominik Dingel
2014-10-17 14:09 ` [PATCH 1/4] s390/mm: recfactor global pgste updates Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09 ` [PATCH 2/4] mm: introduce new VM_NOZEROPAGE flag Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 22:04   ` Dave Hansen
2014-10-17 22:04     ` Dave Hansen
2014-10-18 14:49     ` Dominik Dingel
2014-10-18 14:49       ` Dominik Dingel
2014-10-18 14:49       ` Dominik Dingel
2014-10-18 16:28       ` Dave Hansen [this message]
2014-10-18 16:28         ` Dave Hansen
2014-10-18 16:28         ` Dave Hansen
2014-10-20 18:14         ` Paolo Bonzini
2014-10-20 18:14           ` Paolo Bonzini
2014-10-20 18:14           ` Paolo Bonzini
2014-10-21  6:11           ` Martin Schwidefsky
2014-10-21  6:11             ` Martin Schwidefsky
2014-10-21  6:11             ` Martin Schwidefsky
2014-10-21  8:11             ` Paolo Bonzini
2014-10-21  8:11               ` Paolo Bonzini
2014-10-21  8:11               ` Paolo Bonzini
2014-10-21 11:20               ` Dominik Dingel
2014-10-21 11:20                 ` Dominik Dingel
2014-10-21 11:20                 ` Dominik Dingel
2014-10-17 14:09 ` [PATCH 3/4] s390/mm: prevent and break zero page mappings in case of storage keys Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09 ` [PATCH 4/4] s390/mm: disable KSM for storage key enabled pages Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel
2014-10-17 14:09   ` Dominik Dingel

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