Re: [PATCH v2 0/3] Directed kmem charging

[Christopher Lameter]

On Wed, 21 Feb 2018, Shakeel Butt wrote:

> On Wed, Feb 21, 2018 at 8:09 AM, Christopher Lameter <cl@xxxxxxxxx> wrote:
> > Another way to solve this is to switch the user context right?
> >
> > Isnt it possible to avoid these patches if do the allocation in another
> > task context instead?
> >
>
> Sorry, can you please explain what you mean by 'switch the user
> context'. Is there any example in kernel which does something similar?

See include/linux/task_work.h. One use case is in mntput_no_expire() in
linux/fs/namespace.c

> > Are there really any other use cases beyond fsnotify?
> >
>
> Another use case I have in mind and plan to upstream is to bind a
> filesystem mount with a memcg. So, all the file pages (or anon pages
> for shmem) and kmem (like inodes and dentry) will be charged to that
> memcg.

The mount logic already uses task_work.h. That may be the approach to
expand there.