>>> On 23.07.10 at 15:49, Tim Deegan <Tim.Deegan@xxxxxxxxxx> wrote:
> There are a few places in Xen where we walk a domain's page lists
> without holding the page_alloc lock. They race with updates to the page
> lists, which are normally rare but can be quite common under PoD when
> the domain is close to its memory limit and the PoD reclaimer is busy.
> This patch protects those places by taking the page_alloc lock.
>
> I think this is OK for the two debug-key printouts - they don't run from
> irq context and look deadlock-free. The tboot change seems safe too
While the comment says the patch would leave debug key printouts
alone, ...
> unless tboot shutdown functions are called from irq context or with the
> page_alloc lock held. The p2m one is the scariest but there are already
> code paths in PoD that take the page_alloc lock with the p2m lock held
> so it's no worse than existing code.
>
> Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>
> diff -r e8dbc1262f52 xen/arch/x86/domain.c
> --- a/xen/arch/x86/domain.c Wed Jul 21 09:02:10 2010 +0100
> +++ b/xen/arch/x86/domain.c Fri Jul 23 14:33:22 2010 +0100
> @@ -139,12 +139,14 @@ void dump_pageframe_info(struct domain *
... the actual patch still touches a respective function. It would seem
to me that this part ought to be reverted.
> }
> else
> {
> + spin_lock(&d->page_alloc_lock);
> page_list_for_each ( page, &d->page_list )
> {
> printk(" DomPage %p: caf=%08lx, taf=%" PRtype_info "\n",
> _p(page_to_mfn(page)),
> page->count_info, page->u.inuse.type_info);
> }
> + spin_unlock(&d->page_alloc_lock);
> }
>
> if ( is_hvm_domain(d) )
> @@ -152,12 +154,14 @@ void dump_pageframe_info(struct domain *
> p2m_pod_dump_data(d);
> }
>
> + spin_lock(&d->page_alloc_lock);
> page_list_for_each ( page, &d->xenpage_list )
> {
> printk(" XenPage %p: caf=%08lx, taf=%" PRtype_info "\n",
> _p(page_to_mfn(page)),
> page->count_info, page->u.inuse.type_info);
> }
> + spin_unlock(&d->page_alloc_lock);
> }
>
> struct domain *alloc_domain_struct(void)
Sorry for not noticing this earlier.
Jan
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