On 04/07/2015 12:03 PM, Kirill A. Shutemov wrote:
> On Tue, Apr 07, 2015 at 11:40:06AM +0300, Boaz Harrosh wrote:
>>
>> [v2]
>> Based on linux-next/akpm [3dc4623]. For v4.1 merge window
>> Incorporated comments from Andrew And Kirill
>
> Not really. You've ignored most of them. See below.
>
Yes sorry about that I sent the wrong version.
<>
>> ---
>> include/linux/mm.h | 3 +++
>> mm/memory.c | 35 +++++++++++++++++++++++++++++++----
>
> Please, document it in Documentation/filesystems/Locking.
>
Ha, I missed this one. Ok will try to put something coherent.
<>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index 59f6268..6e8f3f6 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -1982,6 +1982,19 @@ static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
>> return ret;
>> }
>>
>> +static int do_pfn_mkwrite(struct vm_area_struct *vma, unsigned long address)
>> +{
>> + struct vm_fault vmf = {
>> + .page = 0,
>
> .page = NULL,
>
>> + .pgoff = (((address & PAGE_MASK) - vma->vm_start)
>> + >> PAGE_SHIFT) + vma->vm_pgoff,
>
> .pgoff = linear_page_index(vma, address),
>
Yes I had fixes for these two
>> + .virtual_address = (void __user *)(address & PAGE_MASK),
>> + .flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
>> + };
>> +
>> + return vma->vm_ops->pfn_mkwrite(vma, &vmf);
>> +}
>> +
>> /*
>> * Handle write page faults for pages that can be reused in the current vma
>> *
>> @@ -2259,14 +2272,28 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
>> * VM_PFNMAP VMA.
>> *
>> * We should not cow pages in a shared writeable mapping.
>> - * Just mark the pages writable as we can't do any dirty
>> - * accounting on raw pfn maps.
>> + * Just mark the pages writable and/or call ops->pfn_mkwrite.
>> */
>> if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
>> - (VM_WRITE|VM_SHARED))
>> + (VM_WRITE|VM_SHARED)) {
>
> Let's move this case in separate function -- wp_pfn_shared(). As we do for
> wp_page_shared().
>
Ha, OK I will try that. I will need to re-run tests to make sure I did
not mess up
Thanks will fix, makes sense
Boaz
>> + if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
>> + int ret;
>> +
>> + pte_unmap_unlock(page_table, ptl);
>> + ret = do_pfn_mkwrite(vma, address);
>> + if (ret & VM_FAULT_ERROR)
>> + return ret;
>> + page_table = pte_offset_map_lock(mm, pmd,
>> + address, &ptl);
>> + /* Did pfn_mkwrite already fixed up the pte */
>> + if (!pte_same(*page_table, orig_pte)) {
>> + pte_unmap_unlock(page_table, ptl);
>> + return ret;
>> + }
>> + }
>> return wp_page_reuse(mm, vma, address, page_table, ptl,
>> orig_pte, old_page, 0, 0);
>> -
>> + }
>> pte_unmap_unlock(page_table, ptl);
>> return wp_page_copy(mm, vma, address, page_table, pmd,
>> orig_pte, old_page);
--
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