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Date:   Tue, 1 Jun 2021 00:41:37 -0700
From:   Michel Lespinasse <michel@lespinasse.org>
To:     Suren Baghdasaryan <surenb@google.com>
Cc:     "Paul E . McKenney" <paulmck@kernel.org>,
        Michel Lespinasse <michel@lespinasse.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linux-Kernel <linux-kernel@vger.kernel.org>,
        Laurent Dufour <ldufour@linux.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Michal Hocko <mhocko@suse.com>,
        Matthew Wilcox <willy@infradead.org>,
        Rik van Riel <riel@surriel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joel Fernandes <joelaf@google.com>,
        Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH 00/29] Speculative page faults (anon vmas only)
Message-ID: <20210601074137.GC13530@lespinasse.org>
References: <20210430195232.30491-1-michel@lespinasse.org>
 <20210430224649.GA29203@lespinasse.org>
 <20210503181118.GA21048@lespinasse.org>
 <20210517175750.GJ4441@paulmck-ThinkPad-P17-Gen-1>
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On Thu, May 20, 2021 at 03:10:24PM -0700, Suren Baghdasaryan wrote:
> Hi Paul,
> I promised you to look into this but somehow forgot to reply, sorry
> about that. The issue is the new "#include <linux/mm_types.h>" in mm.h
> which causes page_pgdat() usage before it is defined:
> 
> mm.h includes mm_types.h
> mm_types.h includes vmstat.h
> vmstat.h uses page_pgdat()
> mm.h defines page_pgdat()
> 
> Not sure if this is the best way to fix it but this worked fine for me:
> 
> ---
>  include/linux/mmap_lock.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> index 98f24a9910a9..13d4a706c0eb 100644
> --- a/include/linux/mmap_lock.h
> +++ b/include/linux/mmap_lock.h
> @@ -7,7 +7,7 @@
>  #include <linux/rwsem.h>
>  #include <linux/tracepoint-defs.h>
>  #include <linux/types.h>
> -#include <linux/vmstat.h>
> +#include <linux/vm_event_item.h>

Thanks for looking into this.

I have to say, C's handling of header files is one of my least
favourite features, it tends to be very unmaintainable when there are
multiple configs involved :/

I haven't spent any time trying to reproduce the issue yet.
Paul, could you send your .config file to give me a starting point ?
Or maybe Suren already figured out what combination of config options
triggers the issue ?

Thanks,

--
Michel "walken" Lespinasse