On Fri, 23 Oct 2020 at 08:35, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Thu, Oct 22, 2020 at 6:36 PM Daniel Díaz <daniel.diaz@xxxxxxxxxx> wrote: > > > > The kernel Naresh originally referred to is here: > > https://builds.tuxbuild.com/SCI7Xyjb7V2NbfQ2lbKBZw/ > > is unnecessary (because the 8-byte case is still just a single > register, no %eax:%edx games needed), it would be interesting to hear > if the attached patch fixes it. That would confirm that the problem > really is due to some register allocation issue interaction (or, > alternatively, it would tell me that there's something else going on). [Old patch from yesterday] After applying your patch on top on linux next tag 20201015 there are two observations, 1) i386 build failed. please find build error build 2) x86_64 kasan test PASS and the reported error not found. i386 build failure, ---------------------- make -sk KBUILD_BUILD_USER=TuxBuild -C/linux -j16 ARCH=i386 HOSTCC=gcc CC="sccache gcc" O=build # In file included from ../include/linux/uaccess.h:11, from ../arch/x86/include/asm/fpu/xstate.h:5, from ../arch/x86/include/asm/pgtable.h:26, from ../include/linux/pgtable.h:6, from ../include/linux/mm.h:33, from ../include/linux/memblock.h:13, from ../fs/proc/page.c:2: ../fs/proc/page.c: In function ‘kpagecgroup_read’: ../arch/x86/include/asm/uaccess.h:217:2: error: inconsistent operand constraints in an ‘asm’ 217 | asm volatile("call __" #fn "_%P[size]" \ | ^~~ ../arch/x86/include/asm/uaccess.h:244:44: note: in expansion of macro ‘do_put_user_call’ 244 | #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) | ^~~~~~~~~~~~~~~~ ../fs/proc/page.c:307:7: note: in expansion of macro ‘put_user’ 307 | if (put_user(ino, out)) { | ^~~~~~~~ make[3]: *** [../scripts/Makefile.build:283: fs/proc/page.o] Error 1 make[3]: Target '__build' not remade because of errors. make[2]: *** [../scripts/Makefile.build:500: fs/proc] Error 2 In file included from ../include/linux/uaccess.h:11, from ../include/linux/sched/task.h:11, from ../include/linux/sched/signal.h:9, from ../include/linux/rcuwait.h:6, from ../include/linux/percpu-rwsem.h:7, from ../include/linux/fs.h:33, from ../include/linux/cgroup.h:17, from ../include/linux/memcontrol.h:13, from ../include/linux/swap.h:9, from ../include/linux/suspend.h:5, from ../kernel/power/user.c:10: ../kernel/power/user.c: In function ‘snapshot_ioctl’: ../arch/x86/include/asm/uaccess.h:217:2: error: inconsistent operand constraints in an ‘asm’ 217 | asm volatile("call __" #fn "_%P[size]" \ | ^~~ ../arch/x86/include/asm/uaccess.h:244:44: note: in expansion of macro ‘do_put_user_call’ 244 | #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) | ^~~~~~~~~~~~~~~~ ../kernel/power/user.c:340:11: note: in expansion of macro ‘put_user’ 340 | error = put_user(size, (loff_t __user *)arg); | ^~~~~~~~ ../arch/x86/include/asm/uaccess.h:217:2: error: inconsistent operand constraints in an ‘asm’ 217 | asm volatile("call __" #fn "_%P[size]" \ | ^~~ ../arch/x86/include/asm/uaccess.h:244:44: note: in expansion of macro ‘do_put_user_call’ 244 | #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) | ^~~~~~~~~~~~~~~~ ../kernel/power/user.c:346:11: note: in expansion of macro ‘put_user’ 346 | error = put_user(size, (loff_t __user *)arg); | ^~~~~~~~ ../arch/x86/include/asm/uaccess.h:217:2: error: inconsistent operand constraints in an ‘asm’ 217 | asm volatile("call __" #fn "_%P[size]" \ | ^~~ ../arch/x86/include/asm/uaccess.h:244:44: note: in expansion of macro ‘do_put_user_call’ 244 | #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); }) | ^~~~~~~~~~~~~~~~ ../kernel/power/user.c:357:12: note: in expansion of macro ‘put_user’ 357 | error = put_user(offset, (loff_t __user *)arg); | ^~~~~~~~ x86_64 Kasan tested and the reported issue not found. https://lkft.validation.linaro.org/scheduler/job/1868029#L2374 - Naresh
