Re: [Qemu-devel] [PATCH 1/1] mm: gup: teach get_user_pages_unlocked to handle FOLL_NOWAIT

2018-03-02 Thread Andrew Morton
On Fri, 2 Mar 2018 18:43:43 +0100 Andrea Arcangeli wrote: > KVM is hanging during postcopy live migration with userfaultfd because > get_user_pages_unlocked is not capable to handle FOLL_NOWAIT. > > Earlier FOLL_NOWAIT was only ever passed to get_user_pages. > >

[Qemu-devel] [PATCH 1/1] mm: gup: teach get_user_pages_unlocked to handle FOLL_NOWAIT

2018-03-02 Thread Andrea Arcangeli
KVM is hanging during postcopy live migration with userfaultfd because get_user_pages_unlocked is not capable to handle FOLL_NOWAIT. Earlier FOLL_NOWAIT was only ever passed to get_user_pages. Specifically faultin_page (the callee of get_user_pages_unlocked caller) doesn't know that if