Tim Deegan
2013-Mar-28 10:35 UTC
[PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
Xenheap pages will always have an extra typecount, taken in
share_xen_page_with_guest(), which doesn''t come from a shadow PTE.
Adjust the warning in sh_remove_all_mappings() to account for it.
Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Tim Deegan <tim@xen.org>
---
xen/arch/x86/mm/shadow/common.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 4b576ac..adffa06 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -2437,10 +2437,13 @@ int sh_remove_all_mappings(struct vcpu *v, mfn_t gmfn)
{
/* Don''t complain if we''re in HVM and there are some
extra mappings:
* The qemu helper process has an untyped mapping of this
dom''s RAM
- * and the HVM restore program takes another. */
+ * and the HVM restore program takes another.
+ * Also allow one typed refcount for xenheap pages, to match
+ * share_xen_page_with_guest(). */
if ( !(shadow_mode_external(v->domain)
&& (page->count_info & PGC_count_mask) <= 3
- && (page->u.inuse.type_info & PGT_count_mask) ==
0) )
+ && ((page->u.inuse.type_info & PGT_count_mask)
+ == !!is_xen_heap_page(page))) )
{
SHADOW_ERROR("can''t find all mappings of mfn %lx:
"
"c=%08lx t=%08lx\n", mfn_x(gmfn),
--
1.7.10.4
Andrew Cooper
2013-Apr-02 10:09 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
On 28/03/13 10:35, Tim Deegan wrote:> Xenheap pages will always have an extra typecount, taken in > share_xen_page_with_guest(), which doesn''t come from a shadow PTE. > Adjust the warning in sh_remove_all_mappings() to account for it. > > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> > Signed-off-by: Tim Deegan <tim@xen.org>Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>> --- > xen/arch/x86/mm/shadow/common.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c > index 4b576ac..adffa06 100644 > --- a/xen/arch/x86/mm/shadow/common.c > +++ b/xen/arch/x86/mm/shadow/common.c > @@ -2437,10 +2437,13 @@ int sh_remove_all_mappings(struct vcpu *v, mfn_t gmfn) > { > /* Don''t complain if we''re in HVM and there are some extra mappings: > * The qemu helper process has an untyped mapping of this dom''s RAM > - * and the HVM restore program takes another. */ > + * and the HVM restore program takes another. > + * Also allow one typed refcount for xenheap pages, to match > + * share_xen_page_with_guest(). */ > if ( !(shadow_mode_external(v->domain) > && (page->count_info & PGC_count_mask) <= 3 > - && (page->u.inuse.type_info & PGT_count_mask) == 0) ) > + && ((page->u.inuse.type_info & PGT_count_mask) > + == !!is_xen_heap_page(page))) ) > { > SHADOW_ERROR("can''t find all mappings of mfn %lx: " > "c=%08lx t=%08lx\n", mfn_x(gmfn),
Jan Beulich
2013-Apr-05 08:11 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
>>> On 28.03.13 at 11:35, Tim Deegan <tim@xen.org> wrote: > Xenheap pages will always have an extra typecount, taken in > share_xen_page_with_guest(), which doesn''t come from a shadow PTE. > Adjust the warning in sh_remove_all_mappings() to account for it. > > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> > Signed-off-by: Tim Deegan <tim@xen.org>I suppose this ought to go into 4.2.2 and 4.1.5 as well? Jan
Tim Deegan
2013-Apr-05 08:30 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
At 09:11 +0100 on 05 Apr (1365153095), Jan Beulich wrote:> >>> On 28.03.13 at 11:35, Tim Deegan <tim@xen.org> wrote: > > Xenheap pages will always have an extra typecount, taken in > > share_xen_page_with_guest(), which doesn''t come from a shadow PTE. > > Adjust the warning in sh_remove_all_mappings() to account for it. > > > > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> > > Signed-off-by: Tim Deegan <tim@xen.org> > > I suppose this ought to go into 4.2.2 and 4.1.5 as well?Could do -- it''s just suppressing a printk, so not a particularly urgent fix AFAICT. Tim.
Jan Beulich
2013-Apr-05 08:37 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
>>> On 05.04.13 at 10:30, Tim Deegan <tim@xen.org> wrote: > At 09:11 +0100 on 05 Apr (1365153095), Jan Beulich wrote: >> >>> On 28.03.13 at 11:35, Tim Deegan <tim@xen.org> wrote: >> > Xenheap pages will always have an extra typecount, taken in >> > share_xen_page_with_guest(), which doesn''t come from a shadow PTE. >> > Adjust the warning in sh_remove_all_mappings() to account for it. >> > >> > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> >> > Signed-off-by: Tim Deegan <tim@xen.org> >> >> I suppose this ought to go into 4.2.2 and 4.1.5 as well? > > Could do -- it''s just suppressing a printk, so not a particularly urgent > fix AFAICT.But the message, if present when inspecting some random log, looks worrying, so getting rid of the false positive is likely going to help assessing the health of systems/guests. Jan
Tim Deegan
2013-Apr-05 08:46 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
At 09:37 +0100 on 05 Apr (1365154638), Jan Beulich wrote:> >>> On 05.04.13 at 10:30, Tim Deegan <tim@xen.org> wrote: > > At 09:11 +0100 on 05 Apr (1365153095), Jan Beulich wrote: > >> >>> On 28.03.13 at 11:35, Tim Deegan <tim@xen.org> wrote: > >> > Xenheap pages will always have an extra typecount, taken in > >> > share_xen_page_with_guest(), which doesn''t come from a shadow PTE. > >> > Adjust the warning in sh_remove_all_mappings() to account for it. > >> > > >> > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> > >> > Signed-off-by: Tim Deegan <tim@xen.org> > >> > >> I suppose this ought to go into 4.2.2 and 4.1.5 as well? > > > > Could do -- it''s just suppressing a printk, so not a particularly urgent > > fix AFAICT. > > But the message, if present when inspecting some random log, > looks worrying, so getting rid of the false positive is likely going > to help assessing the health of systems/guests.Sure. In any case the patch is harmless, so there should be no risk to putting it in. Tim.
Andrew Cooper
2013-Apr-05 10:40 UTC
Re: [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.
On 05/04/13 09:46, Tim Deegan wrote:> At 09:37 +0100 on 05 Apr (1365154638), Jan Beulich wrote: >>>>> On 05.04.13 at 10:30, Tim Deegan <tim@xen.org> wrote: >>> At 09:11 +0100 on 05 Apr (1365153095), Jan Beulich wrote: >>>>>>> On 28.03.13 at 11:35, Tim Deegan <tim@xen.org> wrote: >>>>> Xenheap pages will always have an extra typecount, taken in >>>>> share_xen_page_with_guest(), which doesn''t come from a shadow PTE. >>>>> Adjust the warning in sh_remove_all_mappings() to account for it. >>>>> >>>>> Reported-by: Andrew Cooper <andrew.cooper3@citrix.com> >>>>> Signed-off-by: Tim Deegan <tim@xen.org> >>>> I suppose this ought to go into 4.2.2 and 4.1.5 as well? >>> Could do -- it''s just suppressing a printk, so not a particularly urgent >>> fix AFAICT. >> But the message, if present when inspecting some random log, >> looks worrying, so getting rid of the false positive is likely going >> to help assessing the health of systems/guests. > Sure. In any case the patch is harmless, so there should be no risk to > putting it in. > > Tim.The reason I started debugging it was because it is an scary message for what turns out to be a safe action. So please backport :) ~Andrew> > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel