lkml.org 
[lkml]   [2008]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [patch 4/6] Guest page hinting: writable page table entries.
    From
    Date
    On Thu, 2008-03-13 at 10:35 +1100, Rusty Russell wrote:
    > On Thursday 13 March 2008 00:21:36 Martin Schwidefsky wrote:
    > > Index: linux-2.6/fs/exec.c
    > > ===================================================================
    > > --- linux-2.6.orig/fs/exec.c
    > > +++ linux-2.6/fs/exec.c
    > > @@ -51,6 +51,7 @@
    > > #include <linux/tsacct_kern.h>
    > > #include <linux/cn_proc.h>
    > > #include <linux/audit.h>
    > > +#include <linux/page-states.h>
    > >
    > > #include <asm/uaccess.h>
    > > #include <asm/mmu_context.h>
    >
    > I haven't compile-tested, but this seems unnecessary; it's the only change to
    > this file.

    True. I removed the include.

    > > +/**
    > > + * __page_reset_writable() - clear the PageWritable bit
    > > + *
    > > + * @page: the page
    > > + */
    > > +void __page_reset_writable(struct page *page)
    > > +{
    > > + preempt_disable();
    > > + if (!page_test_set_state_change(page)) {
    > > + ClearPageWritable(page);
    > > + page_clear_state_change(page);
    > > + }
    > > + preempt_enable();
    > > +}
    > > +EXPORT_SYMBOL(__page_reset_writable);
    >
    > If I understand correctly, you don't bother resetting the writable bit if you
    > don't get the state_change lock. Is this best effort, or is there some
    > correctness issue here?

    It is an error on the safe side. If the page writable bit is set then
    the page state has to indicate to the host that the page dirty bit needs
    to be checked.

    --
    blue skies,
    Martin.

    "Reality continues to ruin my life." - Calvin.




    \
     
     \ /
      Last update: 2008-03-13 10:15    [W:3.049 / U:0.332 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site