Re: [PATCH] drm/ttm: stop warning on TT shrinker failure

[Michal Hocko <mhocko@suse.com>]

On Tue 23-03-21 12:28:20, Daniel Vetter wrote:
> On Tue, Mar 23, 2021 at 08:38:33AM +0100, Michal Hocko wrote:
[...]
> > > > fs_reclaim_acquire is there to make sure lockdep understands that this
> > > > is a shrinker and that it checks all the dependencies for us like if
> > > > we'd be in real reclaim. There is some drop caches interfaces in proc
> > > > iirc, but those drop everything, and they don't have the fs_reclaim
> > > > annotations to teach lockdep about what we're doing.
> > 
> > ... I really do not follow this. You shouldn't really care whether this
> > is a reclaim interface or not. Or maybe I just do not understand this...
> 
> We're heavily relying on lockdep and fs_reclaim to make sure we get it all
> right. So any drop caches interface that isn't wrapped in fs_reclaim
> context is kinda useless for testing. Plus ideally we want to only hit our
> own paths, and not trash every other cache in the system. Speed matters in
> CI.

But what is special about this path to hack around and make it pretend
it is part of the fs reclaim path?
-- 
Michal Hocko
SUSE Labs