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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