Re: [PATCH] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-05-25 Thread Demi Marie Obenour
On Wed, May 25, 2022 at 11:17:39AM +0200, Juergen Gross wrote: > On 24.05.22 18:45, Demi Marie Obenour wrote: > > unmap_grant_pages() currently waits for the pages to no longer be used. > > In https://github.com/QubesOS/qubes-issues/issues/7481, this lead to a > > deadlock against i915: i915 was wa

Re: [PATCH] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-05-25 Thread Juergen Gross
On 24.05.22 18:45, Demi Marie Obenour wrote: unmap_grant_pages() currently waits for the pages to no longer be used. In https://github.com/QubesOS/qubes-issues/issues/7481, this lead to a deadlock against i915: i915 was waiting for gntdev's MMU notifier to finish, while gntdev was waiting for i91

[PATCH] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-05-24 Thread Demi Marie Obenour
unmap_grant_pages() currently waits for the pages to no longer be used. In https://github.com/QubesOS/qubes-issues/issues/7481, this lead to a deadlock against i915: i915 was waiting for gntdev's MMU notifier to finish, while gntdev was waiting for i915 to free its pages. I also believe this is re