From: Pavel Emelyanov <xemul@parallels.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Glauber Costa <glommer@parallels.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Matt Mackall <mpm@selenic.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH 4/5] mm: soft-dirty bits for user memory changes tracking
Date: Fri, 12 Jul 2013 22:38:22 +0400 [thread overview]
Message-ID: <51E04D1E.8060303@parallels.com> (raw)
In-Reply-To: <51DEFD9E.7010703@mit.edu>
On 07/11/2013 10:46 PM, Andy Lutomirski wrote:
>
> Sorry I'm late to the party -- I didn't notice this until the lwn
> article this week.
>
> How does this get munmap + mmap right? mremap marks things soft-dirty,
> but unmapping and remapping seems like it will result in the soft-dirty
> bit being cleared. For that matter, won't this sequence also end up wrong:
>
> - clear_refs
> - Write to mapping
> - Page and pte evicted due to memory pressure
> - Read from mapping -- clean page faulted back in
> - pte soft-dirty is now clear ?!?
Yes, it looks like this problem exists. I'll look what can be done about
it, thank you.
> --Andy
Pavel
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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: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Glauber Costa <glommer@parallels.com>,
KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Matt Mackall <mpm@selenic.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH 4/5] mm: soft-dirty bits for user memory changes tracking
Date: Fri, 12 Jul 2013 22:38:22 +0400 [thread overview]
Message-ID: <51E04D1E.8060303@parallels.com> (raw)
In-Reply-To: <51DEFD9E.7010703@mit.edu>
On 07/11/2013 10:46 PM, Andy Lutomirski wrote:
>
> Sorry I'm late to the party -- I didn't notice this until the lwn
> article this week.
>
> How does this get munmap + mmap right? mremap marks things soft-dirty,
> but unmapping and remapping seems like it will result in the soft-dirty
> bit being cleared. For that matter, won't this sequence also end up wrong:
>
> - clear_refs
> - Write to mapping
> - Page and pte evicted due to memory pressure
> - Read from mapping -- clean page faulted back in
> - pte soft-dirty is now clear ?!?
Yes, it looks like this problem exists. I'll look what can be done about
it, thank you.
> --Andy
Pavel
next prev parent reply other threads:[~2013-07-12 18:38 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-30 16:10 [PATCH 0/5] mm: Ability to monitor task memory changes (v4) Pavel Emelyanov
2013-04-30 16:11 ` [PATCH 1/5] clear_refs: sanitize accepted commands declaration Pavel Emelyanov
2013-04-30 16:11 ` Pavel Emelyanov
2013-04-30 16:11 ` [PATCH 2/5] clear_refs: introduce private struct for mm_walk Pavel Emelyanov
2013-04-30 16:11 ` Pavel Emelyanov
2013-04-30 16:12 ` [PATCH 3/5] pagemap: introduce pagemap_entry_t without pmshift bits Pavel Emelyanov
2013-04-30 16:12 ` Pavel Emelyanov
2013-04-30 16:12 ` [PATCH 4/5] mm: soft-dirty bits for user memory changes tracking Pavel Emelyanov
2013-04-30 16:12 ` Pavel Emelyanov
2013-05-03 11:36 ` Xiao Guangrong
2013-05-03 11:36 ` Xiao Guangrong
2013-05-03 19:09 ` Pavel Emelyanov
2013-05-03 19:09 ` Pavel Emelyanov
2013-07-11 18:46 ` Andy Lutomirski
2013-07-11 18:46 ` Andy Lutomirski
2013-07-12 18:38 ` Pavel Emelyanov [this message]
2013-07-12 18:38 ` Pavel Emelyanov
2013-04-30 16:12 ` [PATCH 5/5] pagemap: Prepare to reuse constant bits with page-shitf Pavel Emelyanov
2013-04-30 16:12 ` Pavel Emelyanov
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