Re: + revert-mm-dont-reclaim-inodes-with-many-attached-pages.patch added to -mm tree

[Dave Chinner <dchinner@redhat.com>]

On Wed, Jan 30, 2019 at 05:54:27AM +0000, Roman Gushchin wrote:
> Hi, Andrew!
> 
> I believe, that Rik's patch ( https://lkml.org/lkml/2019/1/28/1865 ) can make
> a difference here, and might fix the regression. I'd give it a chance, before
> reverting these two patches. Reverting will re-introduce the memcg-leak, which
> is quite bad.

Rik's change is just another hack that will still have effects on
reclaim behaviour.

Indeed, the fs/inode.c change definitely needs reverting, because
that is just *plain wrong* and breaks long-standing memory reclaim
behaviour.

I seriously disagree with shovelling a different, largely untested
and contentious change to the shrinker algorithm to try and patch
over the symptoms of the original change. It leaves the underlying
problem unfixed (dying memcgs need a reaper to shrink the remaining
slab objects that pin that specific memcg) and instead plays
"whack-a-mole" on what we alreayd know is a fundamentally broken
assumption (i.e. that shrinking small slabs more agressively is
side-effect free).

-Dave.
-- 
Dave Chinner
dchinner@redhat.com