Re: [PATCH v4 1/2] writeback: let foreign flushes reach dying cgwbs

[Tejun Heo]

Hello, Liz.

On Wed, Sep 30, 2026 at 07:35:37PM +0000, Liz Fong-Jones wrote:
>  	if (test_bit(WB_registered, &bdi->wb.state) &&
> -	    blkcg_cgwb_list->next && memcg_cgwb_list->next) {
> +	    blkcg_cgwb_list->next && memcg_cgwb_list->next &&
> +	    !css_is_dying(memcg_css)) {

With patch 2 switching a replaced wb's inodes to its successor instead of
flushing them in place, this doesn't matter anymore. If a removed memcg's
wb gets replaced, the successor takes over the inodes and stays in the
tree until released, so foreign flushes still reach them. I asked for it
against v3, where patch 2 only kicked writeback on the old wb. Can you
drop it and the description sentence about it?

Thanks.

--
tejun