On Tue, Oct 13, 2015 at 11:38:38AM +0900, 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@xxxxxxxxxxxxxxx> > Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > Reviewed-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > Hello Greg, > > This patch should go to -stable but when you will apply it > after merging of linus tree, it will be surely conflicted due > to userfaultfd part. > > I want to know how to handle it. You will get an automated email saying it didn't apply and then you provide a backported version. Or you send a properly backported version to stable@xxxxxxxxxxxxxxx before then, with the git commit id of the patch in Linus's tree. thanks, greg k-h -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>