linux-kernel - Re: [PATCH 03/13] mm: meminit: Only set page reserved in the memblock region

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Message-ID: <CA+8MBb+BJSdo6bPFYw1S_ej1-Sp7AEOWVp1V6eXch63B4fG59g@mail.gmail.com>
Date:	Fri, 22 May 2015 13:31:55 -0700
From:	Tony Luck <tony.luck@...il.com>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nathan Zimmer <nzimmer@....com>,
	Dave Hansen <dave.hansen@...el.com>,
	Waiman Long <waiman.long@...com>,
	Scott Norton <scott.norton@...com>,
	Daniel J Blueman <daniel@...ascale.com>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 03/13] mm: meminit: Only set page reserved in the memblock region

On Tue, Apr 28, 2015 at 7:37 AM, Mel Gorman <mgorman@...e.de> wrote:
> Currently each page struct is set as reserved upon initialization.
> This patch leaves the reserved bit clear and only sets the reserved bit
> when it is known the memory was allocated by the bootmem allocator. This
> makes it easier to distinguish between uninitialised struct pages and
> reserved struct pages in later patches.

On ia64 my linux-next builds now report a bunch of messages like this:

put_kernel_page: page at 0xe000000005588000 not in reserved memory
put_kernel_page: page at 0xe000000005588000 not in reserved memory
put_kernel_page: page at 0xe000000005580000 not in reserved memory
put_kernel_page: page at 0xe000000005580000 not in reserved memory
put_kernel_page: page at 0xe000000005580000 not in reserved memory
put_kernel_page: page at 0xe000000005580000 not in reserved memory

the two different pages match up with two objects from the loaded kernel
that get mapped by arch/ia64/mm/init.c:setup_gate()

a000000101588000 D __start_gate_section
a000000101580000 D empty_zero_page

Should I look for a place to set the reserved bit on page structures for these
addresses? Or just remove the test and message in put_kernel_page()
[I added a debug "else" clause here - every caller passes in a page that is
not reserved]

        if (!PageReserved(page))
                printk(KERN_ERR "put_kernel_page: page at 0x%p not in
reserved memory\n",
                       page_address(page));

-Tony
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