Re: [LTP issues] MAP_LOCKED MS_INVALIDATE, dio rw odd count on DAX

[Jan Kara <jack@suse.cz>]

Hi,

going through some old email and found yours...

On Tue 24-01-17 13:24:05, Xiong Zhou wrote:
> LTP tests on DAX show 2 issues.
> 
> msync03 and diotest4, both xfs and ext4,
> 
> non-DAX  pass
> DAX      fail
> 
> 1, MAP_LOCKED && msync with MS_INVALIDATE, which should fail.
> 
> Flag checking code in msync looks ok but missing _LOCK vma falgs
> for DAX mapped vma ? i guess DAX now does not support that ?
> Tracking by LTP testcase "msync03"

So MAP_LOCKED doesn't have a good meaning in case of DAX as there's no page
to lock in memory. Whether we define this means automatic success, failure,
or something else is a question. I don't think anybody has put much thought
into this yet and so results are sometimes rather arbitrary... Thanks for
bringing this up, I'll think about it.

> 2. O_DIRECT rw odd counts on DAX
> 
> read/write 1 byte on file opened with O_DIRECT, EINVAL is
> expected but Success.
> I'm not sure whether this is an issue, please enlighten :)
> Tracking by LTP testcase "dio04 diotest4".

This is expected. Byte addressable memory can handle byte-aligned IOs...

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR