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Date: Mon, 16 Dec 2013 21:27:40 +0100
From: Andrea Arcangeli <aarcange@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Dave Jones <davej@redhat.com>, Darren Hart <dvhart@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, Mel Gorman <mgorman@suse.de>
Subject: Re: [PATCH 0/2] mm: thp: get_huge_page_tail() cleanups
Message-ID: <20131216202740.GF21218@redhat.com>
References: <CA+55aFxLbFWhgzg=Rn0rhUpoOjbTE3QqUSxHTsCyk8GjDUFxJg@mail.gmail.com>
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On Mon, Dec 16, 2013 at 09:19:00PM +0100, Oleg Nesterov wrote:
> On top of
> 
> 	mm-tail-page-refcounting-optimization-for-slab-and-hugetlbfs.patch
> 
> should not be applied without the ack from Andrea.
> 
> On 12/13, Andrea Arcangeli wrote:
> >
> > The above diff looks a straightforward cleanup you could submit it as
> > a separate patch in a v2 series.
> 
> OK, let me send this separately, because (afaics) put_compound_tail()
> needs more thinking.
> 
> See also 2/2. Again, I won't argue if you dislike this change even if
> it is correct, so please review and ack/nack. To me compound_head() in
> get_huge_page_tail() looks confusing, as if get_huge_page_tail() can
> accept a !PageTail page. But perhaps this is only because I am new to
> this code.

compound_head in get_huge_page_tail was just a more readable version
of page->first_page in __get_page_tail_foll. But page->first_page is
faster so it's better.

I reviewed all callers and there's no risk of the VM_BUG_ON triggering
but I prefer it too.

Both patches Acked.

Acked-by: Andrea Arcangeli <aarcange@redhat.com>