linux-kernel - Re: [PATCH] mm:memcg: add __GFP_NOWARN in __memcg_schedule_kmem_cache

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Date:   Wed, 18 Apr 2018 15:39:47 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: [PATCH] mm:memcg: add __GFP_NOWARN in
 __memcg_schedule_kmem_cache_create

On Wed 18-04-18 06:31:39, Matthew Wilcox wrote:
> On Wed, Apr 18, 2018 at 11:29:12AM +0900, Minchan Kim wrote:
> > If there are heavy memory pressure, page allocation with __GFP_NOWAIT
> > fails easily although it's order-0 request.
> > I got below warning 9 times for normal boot.
> > 
> > Let's not make user scared.
> 
> Actually, can you explain why it's OK if this fails?  As I understand this
> code, we'll fail to create a kmalloc cache for this memcg.  What problems
> does that cause?

See http://lkml.kernel.org/r/20180418072002.GN17484@dhcp22.suse.cz

-- 
Michal Hocko
SUSE Labs