2:47 a.m.
On Wed, Sep 02, 2015 at 12:41:44PM +0300, Boaz Harrosh wrote:
On 09/02/2015 12:37 PM, Boaz Harrosh wrote:
>>
>> + /*
>> + * Make sure that for VM_MIXEDMAP VMA has both
>> + * vm_ops->page_mkwrite and vm_ops->pfn_mkwrite or has
none.
>> + */
>> + if ((vma->vm_ops->page_mkwrite ||
vma->vm_ops->pfn_mkwrite) &&
>> + vma->vm_flags & VM_MIXEDMAP) {
>> + VM_BUG_ON_VMA(!vma->vm_ops->page_mkwrite, vma);
>> + VM_BUG_ON_VMA(!vma->vm_ops->pfn_mkwrite, vma);
>
> BTW: the page_mkwrite is used for reading of holes that put zero-pages at the radix
tree.
> One can just map a single global zero-page in pfn-mode for that.
>
> Kirill Hi. Please don't make these BUG_ONs its counter productive believe me.
This is VM_BUG_ON, not normal BUG_ON. VM_BUG_ON is under CONFIG_DEBUG_VM
which is disabled on production kernels.
> Please make them WARN_ON_ONCE() it is not a crashing bug to work
like this.
> (Actually it is not a bug at all in some cases, but we can relax that when a user
> comes up)
>
> Thanks
> Boaz
>
Second thought I do not like this patch. This is why we have xftests for, the fact of it
is that test 080 catches this. For me this is enough.
I don't insist on applying the patch. And I worry about false-positives.
An FS developer should test his code, and worst case we help him on
ML, like we did
in this case.
Thanks
Boaz
>> + }
>> addr = vma->vm_start;
>> vm_flags = vma->vm_flags;
>> } else if (vm_flags & VM_SHARED) {
>>
>
--
Kirill A. Shutemov