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
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