Re: [PATCH] fix pgd_lock deadlock

Andrea Arcangeli
2011-02-22T13:50:44Z

On Tue, Feb 22, 2011 at 07:48:54AM +0000, Jan Beulich wrote:
> A possible alternative would be to acquire the page table lock
> in vmalloc_sync_all() only in the Xen case (perhaps by storing
> NULL into page->index in pgd_set_mm() when not running on
> Xen). This is utilizing the fact that there aren't (supposed to
> be - for non-pvops this is definitely the case) any TLB flush IPIs
> under Xen, and hence the race you're trying to fix doesn't
> exist there (while non-Xen doesn't need the extra locking).

That's sure ok with me. Can we use a global runtime to check if the
guest is running under Xen paravirt, instead of passing that info
through page->something?