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

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Date:   Mon, 9 Oct 2017 08:33:16 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Yang Shi <yang.s@...baba-inc.com>
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        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 Sat 07-10-17 00:37:55, Yang Shi wrote:
> 
> 
> On 10/6/17 2:37 AM, Michal Hocko wrote:
> > On Thu 05-10-17 05:29:10, Yang Shi wrote:
[...]
> > > +	list_for_each_entry_safe(s, s2, &slab_caches, list) {
> > > +		if (!is_root_cache(s) || (s->flags & SLAB_RECLAIM_ACCOUNT))
> > > +			continue;
> > > +
> > > +		memset(&sinfo, 0, sizeof(sinfo));
> > 
> > why do you zero out the structure. All the fields you are printing are
> > filled out in get_slabinfo.
> 
> No special reason, just wipe out the potential stale data on the stack.

Do not add code that has no meaning. The OOM killer is a slow path but
that doesn't mean we should throw spare cycles out of the window.
-- 
Michal Hocko
SUSE Labs