On Mon, Dec 21, 2020 at 11:52:30PM +0800, Muchun Song wrote: > On Mon, Dec 21, 2020 at 9:44 PM Oscar Salvador <osalvador@xxxxxxx> wrote: > > > > On Mon, Dec 21, 2020 at 07:25:15PM +0800, Muchun Song wrote: > > > > > Should we add a BUG_ON in vmemmap_remap_free() for now? > > > > > > BUG_ON(reuse != start + PAGE_SIZE); > > > > I do not think we have to, plus we would be BUG_ing for some specific use > > case in "generic" function. > > The vmemmap_remap_range() walks page table range [start, end), > if reuse is equal to (start + PAGE_SIZE), the range can adjust to > [start - PAGE_SIZE, end). But if not, we need some work to > implement the "generic" function. > > - adjust range to [min(start, reuse), end) and call > vmemmap_remap_rangeand which skip the hole > which is [reuse + PAGE_SIZE, start) or [end, reuse). > - call vmemmap_remap_range(reuse, reuse + PAGE_SIZE) > to get the reuse page.Then, call vmemmap_remap_range(start, end) > again to remap. > > Which one do you prefer? I would not overcomplicate things at this stage. Just follow my sugestion and add a BUG_ON as you said, that might be the easier way now. We can overthink this in the future when some other usecases come around, right? Thanks -- Oscar Salvador SUSE L3
