On Tue, Dec 22, 2020 at 11:44 PM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > On Tue, Dec 22, 2020 at 10:52:09PM +0800, Xie Yongji wrote: > > Export zap_page_range() for use in VDUSE. > > Err, no. This has absolutely no business being used by drivers. Now I want to map/unmap some pages in an userland vma dynamically. The vm_insert_page() is being used for mapping. In the unmapping case, it looks like the zap_page_range() does what I want. So I export it. Otherwise, we need some ways to notify userspace to trigger it with madvise(MADV_DONTNEED), which might not be able to meet all our needs. For example, unmapping some pages in a memory shrinker function. So I'd like to know what's the limitation to use zap_page_range() in a module. And if we can't use it in a module, is there any acceptable way to achieve that? Thanks. Yongji
