On Fri, Jul 26, 2013 at 02:36:51PM -0700, Andy Lutomirski wrote: > >> Unless I'm misunderstanding this, it's saving the bit in the > >> non-present PTE. This sounds wrong -- what happens if the entire pmd > > > > It's the same as encoding pgoff in pte entry (pte is not present), > > but together with pgoff we save soft-bit status, later on #pf we decode > > pgoff and restore softbit back if it was there, pte itself can't disappear > > since it holds pgoff information. > > Isn't that only the case for nonlinear mappings? Andy, I'm somehow lost, pte either exist with file encoded, either not, when pud/ptes are zapped and any access to it should cause #pf pointing kernel to read/write data from file to a page, if it happens on write the pte is obtaining dirty bit (which always set together with soft bit). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>