On Tue, Jun 6, 2023 at 1:15 PM Vlastimil Babka <vbabka@xxxxxxx> wrote: > > On 4/13/23 17:36, Peter Xu wrote: > > On Thu, Apr 13, 2023 at 10:10:44AM +0200, David Hildenbrand wrote: > >> So instead, we consider the whole address space as a virtual, anon file, > >> starting at offset 0. The pgoff of a VMA is then simply the offset in that > >> virtual file (easily computed from the start of the VMA), and VMA merging is > >> just the same as for an ordinary file. > > > > Interesting point, thanks! > > FYI, I've advised a master thesis exploring how to update page->index during > mremap() to keep things mergeable: > > https://dspace.cuni.cz/bitstream/handle/20.500.11956/176288/120426800.pdf > > I think the last RFC posting was: > https://lore.kernel.org/all/20220516125405.1675-1-matenajakub@xxxxxxxxx/ > > It was really tricky for the general case. Maybe it would be more feasible > for the limited case Lokesh describes, if we could be sure the pages that > are moved aren't mapped anywhere else. Lokesh asked me to pick up this work and prepare patches for upstreaming. I'll start working on them after I finish with per-vma lock support for swap and userfaultd (targeting later this week). Thanks for all the input folks!
