From: Pavel Emelyanov <xemul@parallels.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matt Mackall <mpm@selenic.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH] mm: Save soft-dirty bits on file pages
Date: Sat, 27 Jul 2013 23:29:36 +0400 [thread overview]
Message-ID: <51F41FA0.6060205@parallels.com> (raw)
In-Reply-To: <CALCETrUJa-Y40vnb6YOPry0dCXb3zCQ0y19i2yHWdzKR75HUzg@mail.gmail.com>
On 07/27/2013 12:55 AM, Andy Lutomirski wrote:
> On Fri, Jul 26, 2013 at 1:18 PM, Cyrill Gorcunov <gorcunov@gmail.com> wrote:
>> Andy reported that if file page get reclaimed we loose soft-dirty bit
>> if it was there, so save _PAGE_BIT_SOFT_DIRTY bit when page address
>> get encoded into pte entry. Thus when #pf happens on such non-present
>> pte we can restore it back.
>>
>
> Unless I'm misunderstanding this, it's saving the bit in the
> non-present PTE. This sounds wrong -- what happens if the entire pmd
> (or whatever the next level is called) gets zapped? (Also, what
> happens if you unmap a file and map a different file there?)
The whole pte gets zapped on vma unmap, and in this case forgetting
the soft-dirty bit completely is OK.
> --Andy
> .
>
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WARNING: multiple messages have this Message-ID (diff)
From: Pavel Emelyanov <xemul@parallels.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>,
Linux MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Matt Mackall <mpm@selenic.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH] mm: Save soft-dirty bits on file pages
Date: Sat, 27 Jul 2013 23:29:36 +0400 [thread overview]
Message-ID: <51F41FA0.6060205@parallels.com> (raw)
In-Reply-To: <CALCETrUJa-Y40vnb6YOPry0dCXb3zCQ0y19i2yHWdzKR75HUzg@mail.gmail.com>
On 07/27/2013 12:55 AM, Andy Lutomirski wrote:
> On Fri, Jul 26, 2013 at 1:18 PM, Cyrill Gorcunov <gorcunov@gmail.com> wrote:
>> Andy reported that if file page get reclaimed we loose soft-dirty bit
>> if it was there, so save _PAGE_BIT_SOFT_DIRTY bit when page address
>> get encoded into pte entry. Thus when #pf happens on such non-present
>> pte we can restore it back.
>>
>
> Unless I'm misunderstanding this, it's saving the bit in the
> non-present PTE. This sounds wrong -- what happens if the entire pmd
> (or whatever the next level is called) gets zapped? (Also, what
> happens if you unmap a file and map a different file there?)
The whole pte gets zapped on vma unmap, and in this case forgetting
the soft-dirty bit completely is OK.
> --Andy
> .
>
next prev parent reply other threads:[~2013-07-27 19:29 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-26 20:18 [PATCH] mm: Save soft-dirty bits on file pages Cyrill Gorcunov
2013-07-26 20:18 ` Cyrill Gorcunov
2013-07-26 20:55 ` Andy Lutomirski
2013-07-26 20:55 ` Andy Lutomirski
2013-07-26 21:18 ` Cyrill Gorcunov
2013-07-26 21:18 ` Cyrill Gorcunov
2013-07-26 21:36 ` Andy Lutomirski
2013-07-26 21:36 ` Andy Lutomirski
2013-07-27 6:25 ` Cyrill Gorcunov
2013-07-27 6:25 ` Cyrill Gorcunov
2013-07-27 17:06 ` Andy Lutomirski
2013-07-27 17:06 ` Andy Lutomirski
2013-07-27 21:01 ` Cyrill Gorcunov
2013-07-27 21:01 ` Cyrill Gorcunov
2013-07-27 19:29 ` Pavel Emelyanov [this message]
2013-07-27 19:29 ` Pavel Emelyanov
2013-07-28 9:28 ` Pavel Emelyanov
2013-07-28 9:28 ` Pavel Emelyanov
2013-07-29 14:08 ` Pavel Emelyanov
2013-07-29 14:08 ` Pavel Emelyanov
2013-07-29 14:14 ` Cyrill Gorcunov
2013-07-29 14:14 ` Cyrill Gorcunov
2013-07-29 14:24 ` Pavel Emelyanov
2013-07-29 14:24 ` Pavel Emelyanov
2013-07-29 14:36 ` Cyrill Gorcunov
2013-07-29 14:36 ` Cyrill Gorcunov
2013-07-29 14:58 ` Aneesh Kumar K.V
2013-07-29 14:58 ` Aneesh Kumar K.V
2013-07-29 15:02 ` Cyrill Gorcunov
2013-07-29 15:02 ` Cyrill Gorcunov
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