Re: [PATCH v10 7/7] mm,thp: avoid writes to file with THP in pagecache

From: Johannes Weiner
Date: Mon Aug 12 2019 - 16:38:34 EST

On Thu, Aug 01, 2019 at 11:42:44AM -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_dentry_open(), if the file is open for write and
> nr_thps is non-zero, we drop page cache for the whole file.
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
> Acked-by: Rik van Riel <riel@xxxxxxxxxxx>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: Song Liu <songliubraving@xxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>