On Oct 3, 2022, at 3:28 PM, Edgecombe, Rick P <rick.p.edgecombe@xxxxxxxxx> wrote: > On Mon, 2022-10-03 at 11:11 -0700, Nadav Amit wrote: >> Did you have a look at ptep_set_access_flags() and friends and >> checked they >> do not need to be changed too? > > ptep_set_access_flags() doesn't actually set any additional dirty bits > on x86, so I think it's ok. Are you sure about that? (lost my confidence today so I am hesitant). Looking on insert_pfn(), I see: entry = maybe_mkwrite(pte_mkdirty(entry), vma); if (ptep_set_access_flags(vma, addr, pte, entry, 1)) ... This appears to set the dirty bit while potentially leaving the write-bit clear. This is the scenario you want to avoid, no? >> Perhaps you should at least add some >> assertion just to ensure nothing breaks. > > You mean in ptep_set_access_flags()? I think some assertions would be > really great, I'm just not sure where. Yes, on x86’s version of the function.