Re: [PATCH v5 6/6] mm,thp: avoid writes to file with THP in pagecache

[Rik van Riel]

On Thu, 2019-06-20 at 13:53 -0700, Song Liu wrote:
> In previous patch, an application could put part of its text section
> in
> THP via madvise(). These THPs will be protected from writes when the
> application is still running (TXTBSY). However, after the application
> exits, the file is available for writes.
> 
> This patch avoids writes to file THP by dropping page cache for the
> file
> when the file is open for write. A new counter nr_thps is added to
> struct
> address_space. In do_last(), if the file is open for write and
> nr_thps
> is non-zero, we drop page cache for the whole file.
> 
> Signed-off-by: Song Liu <songliubraving@xxxxxx>

Acked-by: Rik van Riel <riel@xxxxxxxxxxx>


The comment for release_file_thp() is a little implementation
specific, which is normally a bad thing (for code we expect
to stick around for years), but probably the right thing for
code that is just a step in the direction we want to go.

Thank you for reworking these patches so quickly.