On Tue, Jul 30, 2024 at 02:46:54PM +0800, alexs@xxxxxxxxxx wrote: > We have struct ptdesc for page table descriptor a year ago, but it > has no much usages in kernel, while pgtable_t is used widely. Hum, I thought I responded to this to point out the problem, but I don't see the response anywhere, so I'll try again. > The pgtable_t is typedefed as 'pte_t *' in sparc, s390, powerpc and m68k > except SUN3, others archs are all same as 'struct page *'. And there's a very good reason for that. On s390 and powerpc (I cannot speak to the sparc/m68k), each page table is (potentially) smaller than PAGE_SIZE. So we cannot do what your patch purports to do, as we would not know whether we're referring to the first or subsequent page tables contained within a page. Maybe at some point in the distant future we'll be able to allocate a ptdesc per page table instead of per page allocated for use by page tables. But we cannot do that yet.
