Return value of __mm_populate

Return value of __mm_populate

[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. 
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

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: Return value of __mm_populate

[KOSAKI Motohiro]

(4/13/13 5:14 AM), Marco Stornelli wrote:
> 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.


> 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?