Hi Matthew, On Thu, Oct 4, 2018 at 1:30 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Thu, Oct 04, 2018 at 12:28:54AM +0530, Souptick Joarder wrote: > > These are the approaches which could have been taken to handle > > this scenario - > > > > * Replace vm_insert_page with vmf_insert_page and then write few > > extra lines of code to convert VM_FAULT_CODE to errno which > > makes driver users more complex ( also the reverse mapping errno to > > VM_FAULT_CODE have been cleaned up as part of vm_fault_t migration , > > not preferred to introduce anything similar again) > > > > * Maintain both vm_insert_page and vmf_insert_page and use it in > > respective places. But it won't gurantee that vm_insert_page will > > never be used in #PF context. > > > > * Introduce a similar API like vm_insert_page, convert all non #PF > > consumer to use it and finally remove vm_insert_page by converting > > it to vmf_insert_page. > > > > And the 3rd approach was taken by introducing vm_insert_kmem_page(). > > > > In short, vmf_insert_page will be used in page fault handlers > > context and vm_insert_kmem_page will be used to map kernel > > memory to user vma outside page fault handlers context. > > As far as I can tell, vm_insert_kmem_page() is line-for-line identical > with vm_insert_page(). Seriously, here's a diff I just did: > > -static int insert_page(struct vm_area_struct *vma, unsigned long addr, > - struct page *page, pgprot_t prot) > +static int insert_kmem_page(struct vm_area_struct *vma, unsigned long addr, > + struct page *page, pgprot_t prot) > - /* Ok, finally just insert the thing.. */ > -int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > +int vm_insert_kmem_page(struct vm_area_struct *vma, unsigned long addr, > - return insert_page(vma, addr, page, vma->vm_page_prot); > + return insert_kmem_page(vma, addr, page, vma->vm_page_prot); > -EXPORT_SYMBOL(vm_insert_page); > +EXPORT_SYMBOL(vm_insert_kmem_page); > > What on earth are you trying to do? Shall I take below approach rather than just creating a identical API same as vm_insert_page ?? 1. create a wrapper function vm_insert_kmem_page using vm_insert_page. 2. Convert all the non #PF users to use it. 3. Then make vm_insert_page static and convert inline vmf_insert_page to caller. In that way we will be having two functions vmf_insert_page (#PF) and vm_insert_kmem_page (non #PF) and both will be using common vm_insert_page which will be static. I am clear with the problem statement but not very clear on my solution.
