Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221103213641.7296-1-shy828301@gmail.com> <20221103213641.7296-2-shy828301@gmail.com>
 <Y2Tc2JNeFWXmZbQ1@dhcp22.suse.cz> <Y2ThtYKSxoP9S44i@dhcp22.suse.cz>
In-Reply-To: <Y2ThtYKSxoP9S44i@dhcp22.suse.cz>
From:   Yang Shi <shy828301@gmail.com>
Date:   Fri, 4 Nov 2022 10:42:45 -0700
Message-ID: <CAHbLzkpvZ05+xSGWLCYKJntsLGzdda449XpjCH7sRE-3S8h+0g@mail.gmail.com>
Subject: Re: [v2 PATCH 2/2] mm: don't warn if the node is offlined
To:     Michal Hocko <mhocko@suse.com>
Cc:     zokeefe@google.com, akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Nov 4, 2022 at 2:56 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Fri 04-11-22 10:35:21, Michal Hocko wrote:
> [...]
> > diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> > index ef4aea3b356e..308daafc4871 100644
> > --- a/include/linux/gfp.h
> > +++ b/include/linux/gfp.h
> > @@ -227,7 +227,10 @@ static inline
> >  struct folio *__folio_alloc_node(gfp_t gfp, unsigned int order, int nid)
> >  {
> >       VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
> > -     VM_WARN_ON((gfp & __GFP_THISNODE) && !node_online(nid));
> > +     if((gfp & __GFP_THISNODE) && !node_online(nid)) {
>
> or maybe even better
>         if ((gfp & (__GFP_THISNODE|__GFP_NOWARN) == __GFP_THISNODE|__GFP_NOWARN) && !node_online(nid))
>
> because it doesn't really make much sense to dump this information if
> the allocation failure is going to provide sufficient (and even more
> comprehensive) context for the failure. It looks more hairy but this can
> be hidden in a nice little helper shared between the two callers.

Thanks a lot for the suggestion, printing warning if the gfp flag
allows sounds like a good idea to me. Will adopt it. But the check
should look like:

if ((gfp & __GFP_THISNODE) && !(gfp & __GFP_NOWARN) && !node_online(nid))

>
> > +             pr_warn("%pGg allocation from offline node %d\n", &gfp, nid);
> > +             dump_stack();
> > +     }
> >
> >       return __folio_alloc(gfp, order, nid, NULL);
> >  }
> > --
> > Michal Hocko
> > SUSE Labs
>
> --
> Michal Hocko
> SUSE Labs