LKML Archive on
help / color / mirror / Atom feed
From: Zachary Amsden <>
To: Hugh Dickins <>
Cc: David Rientjes <>,
	Andrew Morton <>,
	Ingo Molnar <>,
Subject: Re: [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young}
Date: Mon, 26 Mar 2007 12:20:21 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Hugh Dickins wrote:
> On Sun, 25 Mar 2007, Zachary Amsden wrote:
>> If you actually clear the bit, you need to:
>> +         pte_update_defer(vma->vm_mm, addr, ptep);
>> The reason is, when updating PTEs, the hypervisor must be notified.  Using
>> atomic operations to do this is fine for all hypervisors I am aware of.
>> However, for hypervisors which shadow page tables, if these PTE modifications
>> are not trapped, you need a post-modification call to fulfill the update of
>> the shadow page table.
> Thanks for the very rapid response.
> So, David just needs to move the pte_update_defer out of
> ptep_clear_flush_* and into ptep_test_and_clear_*?


> That leaves me wondering why you deleted ptep_test_and_clear_*
> (while leaving their __HAVE_ARCHes) in the first place?

Because raw use of them in the arch independent MM code would introduce 
exactly this bug on i386, so leaving __HAVE_ARCH but leaving out the 
definition would catch this case.


  reply	other threads:[~2007-03-26 19:20 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-26  0:35 [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young} David Rientjes
2007-03-26  0:35 ` [patch -mm 2/2] smaps: use ptep_test_and_clear_young David Rientjes
2007-03-26  5:53 ` [patch -mm 1/2] i386: add ptep_test_and_clear_{dirty,young} Hugh Dickins
2007-03-26  7:07   ` Zachary Amsden
2007-03-26  6:27     ` Hugh Dickins
2007-03-26 20:20       ` Zachary Amsden [this message]
2007-03-26  6:35     ` David Rientjes
2007-03-26 20:22       ` Zachary Amsden

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:

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

  git send-email \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).