Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Demi Marie Obenour
On Fri, Jul 01, 2022 at 07:56:28AM +0200, Juergen Gross wrote: > On 30.06.22 18:54, Demi Marie Obenour wrote: > > On Thu, Jun 30, 2022 at 03:16:41PM +0200, Juergen Gross wrote: > > > On 30.06.22 13:34, Greg KH wrote: > > > > On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: > > >

Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Juergen Gross
On 30.06.22 18:54, Demi Marie Obenour wrote: On Thu, Jun 30, 2022 at 03:16:41PM +0200, Juergen Gross wrote: On 30.06.22 13:34, Greg KH wrote: On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream unmap_grant_pages() curren

[PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 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

Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Demi Marie Obenour
On Thu, Jun 30, 2022 at 03:16:41PM +0200, Juergen Gross wrote: > On 30.06.22 13:34, Greg KH wrote: > > On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: > > > commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream > > > > > > unmap_grant_pages() currently waits for the pages to

Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Greg KH
On Thu, Jun 30, 2022 at 03:16:41PM +0200, Juergen Gross wrote: > On 30.06.22 13:34, Greg KH wrote: > > On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: > > > commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream > > > > > > unmap_grant_pages() currently waits for the pages to

Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Juergen Gross
On 30.06.22 13:34, Greg KH wrote: On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream unmap_grant_pages() currently waits for the pages to no longer be used. In https://github.com/QubesOS/qubes-issues/issues/7481, this lea

Re: [PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-30 Thread Greg KH
On Mon, Jun 27, 2022 at 02:10:02PM -0400, Demi Marie Obenour wrote: > commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream > > 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 i91

[PATCH 5.10] xen/gntdev: Avoid blocking in unmap_grant_pages()

2022-06-27 Thread Demi Marie Obenour
commit dbe97cff7dd9f0f75c524afdd55ad46be3d15295 upstream 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 wait