Re: [External] Re: [PATCH 0/3] memcg, writeback: Don't wait writeback completion

[Julian Sun <sunjunchao@bytedance.com>]

Hi, thanks for your review.

On Wed, Aug 20, 2025 at 8:17 PM Giorgi Tchankvetadze
<giorgitchankvetadze1997@gmail.com> wrote:
>
> Could we add wb_pending_pages to memory.events?
> Very cheap and useful.
> A single atomic counter is already kept internally; exposing it is one
> line in memcontrol.c plus one line in the ABI doc.

Not sure what do you mean by wb_pending_pages? Another counter besides
existing MEMCG_LOW MEMCG_HIGH MEMCG_MAX, etc.? And AFAIK there's no
pending pages in this patch set. Could you give more details?

Thanks,
>
>
> On 8/20/2025 3:19 PM, Julian Sun wrote:
> > This patch series aims to eliminate task hangs in mem_cgroup_css_free()
> > caused by calling wb_wait_for_completion().
> > This is because there may be a large number of writeback tasks in the
> > foreign memcg, involving millions of pages, and the situation is
> > exacerbated by WBT rate limiting—potentially leading to task hangs
> > lasting several hours.
> >
> > Patch 1 is preparatory work and involves no functional changes.
> > Patch 2 implements the automatic release of wb_completion.
> > Patch 3 removes wb_wait_for_completion() from mem_cgroup_css_free().
> >
> >
> > Julian Sun (3):
> >    writeback: Rename wb_writeback_work->auto_free to free_work.
> >    writeback: Add wb_writeback_work->free_done
> >    memcg: Don't wait writeback completion when release memcg.
> >
> >   fs/fs-writeback.c                | 22 ++++++++++++++--------
> >   include/linux/backing-dev-defs.h |  6 ++++++
> >   include/linux/memcontrol.h       |  2 +-
> >   mm/memcontrol.c                  | 29 ++++++++++++++++++++---------
> >   4 files changed, 41 insertions(+), 18 deletions(-)
> >
>