Looks like mips *declares* copy_user_page(), but never *defines* an implementation. It's documented in Documentation/cachetlb.txt, but it's not (currently) called if the architecture defines its own copy_user_highpage(), so some bitrot has occurred. ARM is currently fixing this, and MIPS will need to do the same. (We can't use copy_user_highpage() in DAX because we don't necessarily have a struct page for 'from'.) -----Original Message----- From: Wu, Fengguang Sent: Wednesday, January 21, 2015 9:40 PM To: Andrew Morton Cc: kbuild-all@xxxxxx; Linux Memory Management List; Wilcox, Matthew R Subject: [next:master 4658/4676] undefined reference to `copy_user_page' Hi Andrew, It's probably a bug fix that unveils the link errors. tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: e1e12812e428bcaf19e23f83e09f602d161b8005 commit: c429f45c501ac95383be9e37467d4e6ca08782c1 [4658/4676] daxext2-replace-the-xip-page-fault-handler-with-the-dax-page-fault-handler-fix-3 config: mips-allmodconfig (attached as .config) reproduce: wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout c429f45c501ac95383be9e37467d4e6ca08782c1 # save the attached .config to linux build tree make.cross ARCH=mips All error/warnings: fs/built-in.o: In function `dax_fault': >> (.text+0x5dc6c): undefined reference to `copy_user_page' --- 0-DAY kernel test infrastructure Open Source Technology Center http://lists.01.org/mailman/listinfo/kbuild Intel Corporation
