linux-kernel - Re: [PATCH -next v2] mm/hotplug: silence a lockdep splat with printk()

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Date:   Wed, 15 Jan 2020 10:24:17 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Qian Cai <cai@....pw>
Cc:     akpm@...ux-foundation.org, sergey.senozhatsky.work@...il.com,
        pmladek@...e.com, rostedt@...dmis.org, peterz@...radead.org,
        david@...hat.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next v2] mm/hotplug: silence a lockdep splat with
 printk()

On Wed 15-01-20 10:22:24, Michal Hocko wrote:
[...]
> > @@ -74,9 +75,9 @@ void __dump_page(struct page *page, const char *reason)
> >  			page->mapping, page_to_pgoff(page),
> >  			compound_mapcount(page));
> >  	else
> > -		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx\n",
> > +		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx cma:%d\n",
> >  			page, page_ref_count(page), mapcount,
> > -			page->mapping, page_to_pgoff(page));
> > +			page->mapping, page_to_pgoff(page), page_cma);
> 
> Is this correct? CMA pages cannot be comound? Btw. I would simply do
> 
> 		pr_warn("page:%px refcount:%d mapcount:%d mapping:%px index:%#lx%s\n",
> 			...., page_cmap ? "CMA": "");

Btw. if you rebased on top of http://lkml.kernel.org/r/9f884d5c-ca60-dc7b-219c-c081c755fab6@suse.cz
then the whole thing would be easier AFAICS.
-- 
Michal Hocko
SUSE Labs