Re: [patch v2] mremap.2: Add description of old_size == 0 functionality

Hi Mike,

On 25 September 2017 at 18:33, Mike Kravetz [off-list ref] wrote:

On 09/20/2017 12:25 AM, Michael Kerrisk (man-pages) wrote:

[...]

quoted

I've applied this, and added Reviewed-by tags for Florian and Jann.
But, I think it's also worth noting the older, now disallowed, behavior,
and why the behavior was changed. So I added a note in BUGS:

    BUGS
       Before Linux 4.14, if old_size was zero and the  mapping  referred
       to  by  old_address  was  a private mapping (mmap(2) MAP_PRIVATE),
       mremap() created a new private mapping unrelated to  the  original
       mapping.   This behavior was unintended and probably unexpected in
       user-space applications (since the intention  of  mremap()  is  to
       create  a new mapping based on the original mapping).  Since Linux
       4.14, mremap() fails with the error EINVAL in this scenario.

Does that seem okay?

Sorry for the late reply Michael,  I've been away for a few days.

Yes, the above seems okay.  Thanks for your help with this.

You're welcome. Thanks for checking it over!

Cheers,

Michael

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/