Cced Sasha,
On Tue, Jan 07, 2014 at 12:26:13PM +0800, Wanpeng Li wrote:
>Hi Michal,
>On Mon, Jan 06, 2014 at 03:18:27PM +0100, Michal Hocko wrote:
>>On Mon 06-01-14 20:45:54, Bob Liu wrote:
>>[...]
>>> 544 if (PageAnon(page)) {
>>> 545 struct anon_vma *page__anon_vma = page_anon_vma(page);
>>> 546 /*
>>> 547 * Note: swapoff's unuse_vma() is more efficient with this
>>> 548 * check, and needs it to match anon_vma when KSM is active.
>>> 549 */
>>> 550 if (!vma->anon_vma || !page__anon_vma ||
>>> 551 vma->anon_vma->root != page__anon_vma->root)
>>> 552 return -EFAULT;
>>> 553 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
>>> 554 if (!vma->vm_file ||
>>> 555 vma->vm_file->f_mapping != page->mapping)
>>> 556 return -EFAULT;
>>> 557 } else
>>> 558 return -EFAULT;
>>>
>>> That's the "other conditions" and the reason why we can't use
>>> BUG_ON(!vma) in new_vma_page().
>>
>>Sorry, I wasn't clear with my question. I was interested in which of
>>these triggered and why only for hugetlb pages?
>
>Not just for hugetlb pages, sorry for do two things in one patch. The change
>for hugetlb pages is to fix the potential dereference NULL pointer reported
>by Dan. http://marc.info/?l=linux-mm&m=137689530323257&w=2
>
>If we should ask Sasha to add more debug information to dump which condition
>is failed in page_address_in_vma() for you?
>
>Regards,
>Wanpeng Li
>
>
>>
>>--
>>Michal Hocko
>>SUSE Labs
>
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