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From: Jonathan Corbet <corbet@lwn.net>
To: Eric B Munson <emunson@akamai.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.cz>, Vlastimil Babka <vbabka@suse.cz>,
	linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mips@linux-mips.org, linux-parisc@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
	linux-xtensa@linux-xtensa.org, linux-mm@kvack.org,
	linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH V3 3/5] mm: mlock: Introduce VM_LOCKONFAULT and add mlock flags to enable it
Date: Fri, 10 Jul 2015 10:11:18 -0600	[thread overview]
Message-ID: <20150710101118.5d04d627@lwn.net> (raw)
In-Reply-To: <20150709184635.GE4669@akamai.com>

On Thu, 9 Jul 2015 14:46:35 -0400
Eric B Munson <emunson@akamai.com> wrote:

> > One other question...if I call mlock2(MLOCK_ONFAULT) on a range that
> > already has resident pages, I believe that those pages will not be locked
> > until they are reclaimed and faulted back in again, right?  I suspect that
> > could be surprising to users.  
> 
> That is the case.  I am looking into what it would take to find only the
> present pages in a range and lock them, if that is the behavior that is
> preferred I can include it in the updated series.

For whatever my $0.02 is worth, I think that should be done.  Otherwise
the mlock2() interface is essentially nondeterministic; you'll never
really know if a specific page is locked or not.

Thanks,

jon

WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Corbet <corbet@lwn.net>
To: Eric B Munson <emunson@akamai.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.cz>, Vlastimil Babka <vbabka@suse.cz>,
	linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mips@linux-mips.org, linux-parisc@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
	linux-xtensa@linux-xtensa.org, linux-mm@kvack.org,
	linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH V3 3/5] mm: mlock: Introduce VM_LOCKONFAULT and add mlock flags to enable it
Date: Fri, 10 Jul 2015 16:11:18 +0000	[thread overview]
Message-ID: <20150710101118.5d04d627@lwn.net> (raw)
In-Reply-To: <20150709184635.GE4669@akamai.com>

On Thu, 9 Jul 2015 14:46:35 -0400
Eric B Munson <emunson@akamai.com> wrote:

> > One other question...if I call mlock2(MLOCK_ONFAULT) on a range that
> > already has resident pages, I believe that those pages will not be locked
> > until they are reclaimed and faulted back in again, right?  I suspect that
> > could be surprising to users.  
> 
> That is the case.  I am looking into what it would take to find only the
> present pages in a range and lock them, if that is the behavior that is
> preferred I can include it in the updated series.

For whatever my $0.02 is worth, I think that should be done.  Otherwise
the mlock2() interface is essentially nondeterministic; you'll never
really know if a specific page is locked or not.

Thanks,

jon

WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Corbet <corbet@lwn.net>
To: Eric B Munson <emunson@akamai.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@suse.cz>, Vlastimil Babka <vbabka@suse.cz>,
	linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mips@linux-mips.org, linux-parisc@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
	linux-xtensa@linux-xtensa.org, linux-mm@kvack.org,
	linux-arch@vger.kernel.org, linux-api@vger.kernel.org
Subject: Re: [PATCH V3 3/5] mm: mlock: Introduce VM_LOCKONFAULT and add mlock flags to enable it
Date: Fri, 10 Jul 2015 10:11:18 -0600	[thread overview]
Message-ID: <20150710101118.5d04d627@lwn.net> (raw)
In-Reply-To: <20150709184635.GE4669@akamai.com>

On Thu, 9 Jul 2015 14:46:35 -0400
Eric B Munson <emunson@akamai.com> wrote:

> > One other question...if I call mlock2(MLOCK_ONFAULT) on a range that
> > already has resident pages, I believe that those pages will not be locked
> > until they are reclaimed and faulted back in again, right?  I suspect that
> > could be surprising to users.  
> 
> That is the case.  I am looking into what it would take to find only the
> present pages in a range and lock them, if that is the behavior that is
> preferred I can include it in the updated series.

For whatever my $0.02 is worth, I think that should be done.  Otherwise
the mlock2() interface is essentially nondeterministic; you'll never
really know if a specific page is locked or not.

Thanks,

jon

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  reply	other threads:[~2015-07-10 16:11 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-07 17:03 [PATCH V3 0/5] Allow user to request memory to be locked on page fault Eric B Munson
2015-07-07 17:03 ` Eric B Munson
2015-07-07 17:03 ` Eric B Munson
2015-07-07 17:03 ` [PATCH V3 1/5] mm: mlock: Refactor mlock, munlock, and munlockall code Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03 ` [PATCH V3 2/5] mm: mlock: Add new mlock, munlock, and munlockall system calls Eric B Munson
2015-07-07 17:03 ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-08  6:46   ` Heiko Carstens
2015-07-08  6:46     ` Heiko Carstens
2015-07-08  6:46     ` Heiko Carstens
2015-07-08  6:46     ` Heiko Carstens
2015-07-08  6:46     ` Heiko Carstens
2015-07-08  7:02     ` Geert Uytterhoeven
2015-07-08  7:02       ` Geert Uytterhoeven
2015-07-08  7:02       ` Geert Uytterhoeven
2015-07-08  7:02       ` Geert Uytterhoeven
2015-07-08  7:02       ` Geert Uytterhoeven
2015-07-08  7:02       ` Geert Uytterhoeven
2015-07-08  7:02     ` Geert Uytterhoeven
2015-07-08 11:06   ` Catalin Marinas
     [not found]   ` <1436288623-13007-3-git-send-email-emunson-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org>
2015-07-08 11:06     ` Catalin Marinas
2015-07-08 11:06       ` Catalin Marinas
2015-07-08 11:06       ` Catalin Marinas
2015-07-08 11:06       ` Catalin Marinas
2015-07-08 11:06       ` Catalin Marinas
2015-07-08 11:06       ` Catalin Marinas
2015-07-07 17:03 ` [PATCH V3 3/5] mm: mlock: Introduce VM_LOCKONFAULT and add mlock flags to enable it Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-08 19:23   ` Jonathan Corbet
2015-07-08 19:23     ` Jonathan Corbet
2015-07-08 19:23     ` Jonathan Corbet
2015-07-08 20:34     ` Eric B Munson
2015-07-08 20:34       ` Eric B Munson
2015-07-08 21:17       ` Jonathan Corbet
2015-07-08 21:17         ` Jonathan Corbet
2015-07-08 21:17         ` Jonathan Corbet
2015-07-08 21:17         ` Jonathan Corbet
2015-07-08 21:17         ` Jonathan Corbet
2015-07-08 21:17         ` Jonathan Corbet
2015-07-09 18:46         ` Eric B Munson
2015-07-09 18:46           ` Eric B Munson
2015-07-10 16:11           ` Jonathan Corbet [this message]
2015-07-10 16:11             ` Jonathan Corbet
2015-07-10 16:11             ` Jonathan Corbet
     [not found]             ` <20150710101118.5d04d627-T1hC0tSOHrs@public.gmane.org>
2015-07-10 16:19               ` Eric B Munson
2015-07-10 16:19                 ` Eric B Munson
2015-07-10 16:19                 ` Eric B Munson
2015-07-21 15:35                 ` Vlastimil Babka
2015-07-21 15:35                   ` Vlastimil Babka
2015-07-21 15:35                   ` Vlastimil Babka
2015-07-07 17:03 ` [PATCH V3 4/5] mm: mmap: Add mmap flag to request VM_LOCKONFAULT Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-07 17:03   ` Eric B Munson
2015-07-18 19:11   ` Paul Gortmaker
2015-07-18 19:11     ` Paul Gortmaker
2015-07-20 20:40     ` Chris Metcalf
2015-07-20 20:40       ` Chris Metcalf
2015-07-20 20:40       ` Chris Metcalf
2015-07-21 15:37       ` Eric B Munson
2015-07-22 14:10         ` Paul Gortmaker
2015-07-22 14:10           ` Paul Gortmaker
2015-07-22 14:10           ` Paul Gortmaker
     [not found] ` <1436288623-13007-1-git-send-email-emunson-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org>
2015-07-07 17:03   ` [PATCH V3 5/5] selftests: vm: Add tests for lock on fault Eric B Munson
2015-07-07 17:03     ` Eric B Munson
2015-07-07 17:03     ` Eric B Munson
     [not found]     ` <1436288623-13007-6-git-send-email-emunson-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org>
2015-07-07 21:51       ` Andrew Morton
2015-07-07 21:51         ` Andrew Morton
2015-07-07 21:51         ` Andrew Morton
2015-07-07 21:16   ` [PATCH V3 0/5] Allow user to request memory to be locked on page fault Andrew Morton
2015-07-07 21:16     ` Andrew Morton
2015-07-07 21:16     ` Andrew Morton
2015-07-07 21:16     ` Andrew Morton
2015-07-08 13:23     ` Eric B Munson
2015-07-08 13:23       ` Eric B Munson
2015-07-08 17:00       ` Andrew Morton
2015-07-08 17:00         ` Andrew Morton
2015-07-08 17:00         ` Andrew Morton

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