This is a VM question more than a ptrace question. I can't give you any authoritative answers about the VM issues. Documentation/cachetlb.txt says: Any time the kernel writes to a page cache page, _OR_ the kernel is about to read from a page cache page and user space shared/writable mappings of this page potentially exist, this routine is called. In your case, the kernel is only reading (write=0 passed to access_process_vm and get_user_pages). In normal situations, the page in question will have only a private and read-only mapping in user space. So the call should not be required in these cases--if the code can tell that's so. Perhaps something like the following would be safe. But you really need some VM folks to tell you for sure. diff --git a/mm/memory.c b/mm/memory.c index 02e48aa..2864ee7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1484,7 +1484,8 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, pages[i] = page; flush_anon_page(vma, page, start); - flush_dcache_page(page); + if ((vm_flags & VM_WRITE) || (vma->vm_flags & VM_SHARED) + flush_dcache_page(page); } if (vmas) vmas[i] = vma; Thanks, Roland -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>