Re: [PATCH V2] mm: fix kernel crash in khugepaged thread

[Kirill A. Shutemov]

On Thu, Nov 05, 2015 at 09:12:34AM +0100, Vlastimil Babka wrote:
> On 10/29/2015 01:35 AM, Kirill A. Shutemov wrote:
> >> @@ -2605,9 +2603,9 @@ out_unmap:
> >>  		/* collapse_huge_page will return with the mmap_sem released */
> >>  		collapse_huge_page(mm, address, hpage, vma, node);
> >>  	}
> >> -out:
> >> -	trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced,
> >> -				     none_or_zero, result, unmapped);
> >> +	trace_mm_khugepaged_scan_pmd(mm, pte_present(pteval) ?
> >> +			pte_pfn(pteval) : -1, writable, referenced,
> >> +			none_or_zero, result, unmapped);
> > 
> > maybe passing down pte instead of pfn?
> 
> Maybe just pass the page, and have tracepoint's fast assign check for !NULL and
> do page_to_pfn itself? That way the complexity and overhead is only in the
> tracepoint and when enabled.

Agreed.

-- 
 Kirill A. Shutemov
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