On Wed, Apr 19, 2023 at 03:22:19PM -0300, Jason Gunthorpe wrote: > On Wed, Apr 19, 2023 at 07:18:26PM +0100, Lorenzo Stoakes wrote: > > > I'd also argue that we are doing things right with this patch series as-is, > > io_uring is the only sticking point because, believe it or not, it is the > > only place in the kernel that uses multiple vmas (it has been interesting > > to get a view on GUP use as a whole here). > > I would say io_uring is the only place trying to open-code bug fixes > for MM problems :\ As Jens says, these sorts of temporary work arounds become > lingering problems that nobody wants to fix properly. > > > So even if I did the FOLL_ALLOW_BROKEN_FILE_MAPPING patch series first, I > > would still need to come along and delete a bunch of your code > > afterwards. And unfortunately Pavel's recent change which insists on not > > having different vm_file's across VMAs for the buffer would have to be > > reverted so I expect it might not be entirely without discussion. > > Yeah, that should just be reverted. > > > However, if you really do feel that you can't accept this change as-is, I > > can put this series on hold and look at FOLL_ALLOW_BROKEN_FILE_MAPPING and > > we can return to this afterwards. > > It is probably not as bad as you think, I suspect only RDMA really > wants to set the flag. Maybe something in media too, maybe. > > Then again that stuff doesn't work so incredibly badly maybe there > really is no user of it and we should just block it completely. > > Jason OK in this case I think we're all agreed that it's best to do this first then revisit this series afterwards. I will switch to working on this! And I will make sure to cc- everyone in :)
