Re: [PATCH 1/1] mm: bdi: Initialize bdi_min_ratio when bdi unregister

[Matthew Wilcox]

On Thu, Oct 21, 2021 at 07:45:30PM -0700, Andrew Morton wrote:
> On Thu, 21 Oct 2021 13:01:30 +0100 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
> 
> > On Thu, Oct 21, 2021 at 04:16:52AM -0700, Christoph Hellwig wrote:
> > > On Fri, Oct 22, 2021 at 01:19:43AM +0900, Manjong Lee wrote:
> > > > Because when sdcard is removed, bdi_min_ratio value will remain.
> > > > Currently, the only way to reset bdi_ min_ratio is to reboot.
> > > 
> > > But bdis that are unregistered are never re-registered.  What is
> > > the problem you're trying to solve?
> > 
> > The global bdi_min_ratio needs to be adjusted.  See
> > bdi_set_min_ratio() in mm/page-writeback.c.
> 
> I added cc:stable to this and tweaked the comment & coding style a bit:

Definitely improvements on that front.

I don't know the BDI code particularly well, and the implementation of
bdi_set_min_ratio() confuses me, so I can't say whether the original
patch is clearly correct or not.