On 08/22/2012 12:12 PM, Hugh Dickins wrote: > On Wed, 22 Aug 2012, Xiao Guangrong wrote: >> On 08/21/2012 11:06 PM, Andrea Arcangeli wrote: >>> >>> The KSM usage of it looks safe because it will only establish readonly >>> ptes with it. >> >> Hmm, in KSM code, i found this code in replace_page: >> >> set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); >> >> It is possible to establish a writable pte, no? > > No: we only do KSM in private vmas (!VM_SHARED), and because of the > need to CopyOnWrite in those, vm_page_prot excludes write permission: > write permission has to be added on COW fault. After read the code carefully, yes, you are right. Thank you very much for your explanation, Hugh! :) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
