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

[Giorgi Tchankvetadze <giorgitchankvetadze1997@gmail.com>]

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.


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(-)
>