Re: [PATCH v4 0/3] mm: improvements in shrink slab

[Michal Hocko <mhocko@suse.com>]

On Thu 06-06-19 18:14:37, Yafang Shao wrote:
> In the past few days, I found an issue in shrink slab.
> We I was trying to fix it, I find there are something in shrink slab need
> to be improved.
> 
> - #1 is to expose the min_slab_pages to help us analyze shrink slab.
> 
> - #2 is an code improvement.
> 
> - #3 is a fix to a issue. This issue is very easy to produce.
> In the zone reclaim mode.
> First you continuously cat a random non-exist file to produce
> more and more dentry, then you read big file to produce page cache.
> Finally you will find that the denty will never be shrunk.
> In order to fix this issue, a new bitmask no_pagecache is introduce,
> which is 0 by defalt.

Node reclaim mode is quite special and rarely used these days. Could you
be more specific on how did you get to see the above problems? Do you
really need node reclaim in your usecases or is this more about a
testing and seeing what happens. Not that I am against these changes but
I would like to understand the motivation. Especially because you are
exposing some internal implementation details of the node reclaim to the
userspace.

-- 
Michal Hocko
SUSE Labs