Return value of __mm_populate

Hi,

I was seeing the code of __mm_populate (in -next) and I've got a doubt about the return value. The function __mlock_posix_error_return should return a proper error for mlock, converting the return value from __get_user_pages. It checks for EFAULT and ENOMEM. Actually __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON. So it seems to me that we could return to user space not expected value. I can't see them on the man page. In addition we shouldn't ever return ERESTARTSYS to the user space but EINTR. According to the man pages maybe we should return EAGAIN in these cases. Am I missing something?

Thanks,

Marco

Hi,

I was seeing the code of __mm_populate (in -next) and I've got a doubt about the return value. The function __mlock_posix_error_return should return a proper error for mlock, converting the return value from __get_user_pages. It checks for EFAULT and ENOMEM. Actually __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.

So it seems to me that we could return to user space not expected value. I can't see them on the man page. In addition we shouldn't ever return ERESTARTSYS to the user space but EINTR. According to the man pages maybe we should return EAGAIN in these cases. Am I missing something?

Quoted 7 lines · Marco Stornelli

Hi,

I was seeing the code of __mm_populate (in -next) and I've got a doubt about the return value. The function __mlock_posix_error_return should return a proper error for mlock, converting the return value from __get_user_pages. It checks for EFAULT and ENOMEM. Actually __get_user_pages could return, in addition, ERESTARTSYS and EHWPOISON.

__get_user_pages doesn't return EHWPOISON if FOLL_HWPOISON is not specified. I'm not expert ERESTARTSYS. I understand correctly, ERESTARTSYS is only returned when signal received, and signal handling routine (e.g. do_signal) modify EIP and hidden ERESTARTSYS from userland generically.