Messages in this thread | | | Date | Tue, 13 Oct 2015 18:10:53 +0900 | From | Minchan Kim <> | Subject | Re: [PATCH v2] thp: use is_zero_pfn only after pte_present check |
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On Tue, Oct 13, 2015 at 09:28:23AM +0200, Vlastimil Babka wrote: > On 10/13/2015 04:38 AM, Minchan Kim wrote: > >Use is_zero_pfn on pteval only after pte_present check on pteval > >(It might be better idea to introduce is_zero_pte where checks > >pte_present first). Otherwise, it could work with swap or > >migration entry and if pte_pfn's result is equal to zero_pfn > >by chance, we lose user's data in __collapse_huge_page_copy. > >So if you're luck, the application is segfaulted and finally you > >could see below message when the application is exit. > > > >BUG: Bad rss-counter state mm:ffff88007f099300 idx:2 val:3 > > > >Cc: <stable@vger.kernel.org> > > More specific: > Cc: <stable@vger.kernel.org> # 4.1+ > Fixes: ca0984caa823 ("mm: incorporate zero pages into transparent > huge pages") > > >Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > > Acked-by: Vlastimil Babka <vbabka@suse.cz>
Thanks for the detail and review, Vlastimil.
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