>>> On 29.04.19 at 18:42, <george.dun...@citrix.com> wrote: > On 4/29/19 4:18 PM, Jan Beulich wrote: >>>>> On 26.04.19 at 19:21, <ta...@tklengyel.com> wrote: >>> Patch cf4b30dca0a "Add debug code to detect illegal page_lock and > put_page_type >>> ordering" added extra sanity checking to page_lock/page_unlock for debug > builds >>> with the assumption that no hypervisor path ever locks two pages at once. >>> >>> This assumption doesn't hold during memory sharing so we introduce separate >>> functions, page_lock_memshr and page_unlock_memshr, to be used exclusively >>> in the memory sharing subsystem. >> >> Completely bypassing these checks looks undesirable to me, to >> be honest. Otoh as discussed mem-sharing is abusing the lock >> anyway. > > I'm not sure what you mean by "abusing"; would it be any different if > page_struct() had a spinlock element called "page_lock", that was only > used by PV guests?
No, it wouldn't. By "abusing" I mean it is using something for HVM which is meant to be used for PV only. It is mem-sharing's use alone which prevents page_{,un}lock() to be put inside #ifdef CONFIG_PV. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel