On Fri, Jun 21, 2024 at 11:16:31AM +0100, Fuad Tabba wrote: > Hi David, > > On Fri, Jun 21, 2024 at 10:10 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > > > On 21.06.24 10:54, Fuad Tabba wrote: > > > Hi David, > > > > > > On Fri, Jun 21, 2024 at 9:44 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > >> > > >>>> Again from that thread, one of most important aspects guest_memfd is that VMAs > > >>>> are not required. Stating the obvious, lack of VMAs makes it really hard to drive > > >>>> swap, reclaim, migration, etc. from code that fundamentally operates on VMAs. > > >>>> > > >>>> : More broadly, no VMAs are required. The lack of stage-1 page tables are nice to > > >>>> : have; the lack of VMAs means that guest_memfd isn't playing second fiddle, e.g. > > >>>> : it's not subject to VMA protections, isn't restricted to host mapping size, etc. > > >>>> > > >>>> [1] https://lore.kernel.org/all/Zfmpby6i3PfBEcCV@xxxxxxxxxx > > >>>> [2] https://lore.kernel.org/all/Zg3xF7dTtx6hbmZj@xxxxxxxxxx > > >>> > > >>> I wonder if it might be more productive to also discuss this in one of > > >>> the PUCKs, ahead of LPC, in addition to trying to go over this in LPC. > > >> > > >> I don't know in which context you usually discuss that, but I could > > >> propose that as a topic in the bi-weekly MM meeting. > > >> > > >> This would, of course, be focused on the bigger MM picture: how to mmap, > > >> how how to support huge pages, interaction with page pinning, ... So > > >> obviously more MM focused once we are in agreement that we want to > > >> support shared memory in guest_memfd and how to make that work with core-mm. > > >> > > >> Discussing if we want shared memory in guest_memfd might be betetr > > >> suited for a different, more CC/KVM specific meeting (likely the "PUCKs" > > >> mentioned here?). > > > > > > Sorry, I should have given more context on what a PUCK* is :) It's a > > > periodic (almost weekly) upstream call for KVM. > > > > > > [*] https://lore.kernel.org/all/20230512231026.799267-1-seanjc@xxxxxxxxxx/ > > > > > > But yes, having a discussion in one of the mm meetings ahead of LPC > > > would also be great. When do these meetings usually take place, to try > > > to coordinate across timezones. > > > > It's Wednesday, 9:00 - 10:00am PDT (GMT-7) every second week. > > > > If we're in agreement, we could (assuming there are no other planned > > topics) either use the slot next week (June 26) or the following one > > (July 10). > > > > Selfish as I am, I would prefer July 10, because I'll be on vacation > > next week and there would be little time to prepare. > > > > @David R., heads up that this might become a topic ("shared and private > > memory in guest_memfd: mmap, pinning and huge pages"), if people here > > agree that this is a direction worth heading. > > Thanks for the invite! Tentatively July 10th works for me, but I'd > like to talk to the others who might be interested (pKVM, Gunyah, and > others) to see if that works for them. I'll get back to you shortly. > I'd like to join too, July 10th at that time works for me. - Elliot
