linux-kernel - Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when unreclaimable slabs

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Message-ID: <alpine.DEB.2.10.1710171537170.141832@chino.kir.corp.google.com>
Date:   Tue, 17 Oct 2017 15:39:08 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Yang Shi <yang.s@...baba-inc.com>
cc:     Michal Hocko <mhocko@...nel.org>, cl@...ux.com, penberg@...nel.org,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] mm: oom: show unreclaimable slab info when unreclaimable
 slabs > user memory

On Wed, 18 Oct 2017, Yang Shi wrote:

> > Yes, this should catch occurrences of "huge unreclaimable slabs", right?
> 
> Yes, it sounds so. Although single "huge" unreclaimable slab might not result
> in excessive slabs use in a whole, but this would help to filter out "small"
> unreclaimable slab.
> 

Keep in mind this is regardless of SLAB_RECLAIM_ACCOUNT: your patch has 
value beyond only unreclaimable slab, it can also be used to show 
instances where the oom killer was invoked without properly reclaiming 
slab.  If the total footprint of a slab cache exceeds 5%, I think a line 
should be emitted unconditionally to the kernel log.