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In-Reply-To: <1256712464-21472-8-git-send-email-fujita.tomonori@lab.ntt.co.jp>
References: <1256712464-21472-1-git-send-email-fujita.tomonori@lab.ntt.co.jp>
	 <1256712464-21472-8-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Date: Mon, 9 Nov 2009 22:13:40 +0200
Message-ID: <84144f020911091213j393a9761pe13808d1e091e169@mail.gmail.com>
Subject: Re: [PATCH 07/10] bootmem: add free_bootmem_late
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: linux-kernel@vger.kernel.org, chrisw@sous-sol.org, dwmw2@infradead.org,
       joerg.roedel@amd.com, mingo@elte.hu,
       Andrew Morton <akpm@linux-foundation.org>,
       Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>
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On Wed, Oct 28, 2009 at 8:47 AM, FUJITA Tomonori
<fujita.tomonori@lab.ntt.co.jp> wrote:
> @@ -151,7 +151,9 @@ unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
> ?*
> ?* This will free the pages in the range @start to @end, making them
> ?* available to the page allocator. ?The @map will be used to skip
> - * reserved pages. ?Returns the count of pages freed.
> + * reserved pages. ?In the case that @map is NULL, the bootmem allocator
> + * is already free and the range is contiguous. ?Returns the count of
> + * pages freed.
> ?*/
> ?static unsigned long __init free_bootmem_pages(unsigned long start,
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? unsigned long end,
> @@ -164,13 +166,23 @@ static unsigned long __init free_bootmem_pages(unsigned long start,
> ? ? ? ? * If the start is aligned to the machines wordsize, we might
> ? ? ? ? * be able to free pages in bulks of that order.
> ? ? ? ? */
> - ? ? ? aligned = !(start & (BITS_PER_LONG - 1));
> + ? ? ? if (map)
> + ? ? ? ? ? ? ? aligned = !(start & (BITS_PER_LONG - 1));
> + ? ? ? else
> + ? ? ? ? ? ? ? aligned = 1;

Why do we need this special casing here? Isn't start always aligned
properly for callers with map == NULL?

>
> ? ? ? ?for (cursor = start; cursor < end; cursor += BITS_PER_LONG) {
> - ? ? ? ? ? ? ? unsigned long idx, vec;
> + ? ? ? ? ? ? ? unsigned long vec;
>
> - ? ? ? ? ? ? ? idx = cursor - start;
> - ? ? ? ? ? ? ? vec = ~map[idx / BITS_PER_LONG];
> + ? ? ? ? ? ? ? if (map) {
> + ? ? ? ? ? ? ? ? ? ? ? unsigned long idx = cursor - start;
> + ? ? ? ? ? ? ? ? ? ? ? vec = ~map[idx / BITS_PER_LONG];
> + ? ? ? ? ? ? ? } else {
> + ? ? ? ? ? ? ? ? ? ? ? if (end - cursor >= BITS_PER_LONG)
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? vec = ~0UL;

Why do we need the above?

> + ? ? ? ? ? ? ? ? ? ? ? else
> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? vec = (1UL << (end - cursor)) - 1;
> + ? ? ? ? ? ? ? }
>
> ? ? ? ? ? ? ? ?if (aligned && vec == ~0UL && cursor + BITS_PER_LONG < end) {
> ? ? ? ? ? ? ? ? ? ? ? ?int order = ilog2(BITS_PER_LONG);
> @@ -387,6 +399,27 @@ void __init free_bootmem(unsigned long addr, unsigned long size)
> ?}
>
> ?/**
> + * free_bootmem_late - free bootmem pages directly to page allocator
> + * @addr: starting address of the range
> + * @size: size of the range in bytes
> + *
> + * This is only useful when the bootmem allocator has already been torn
> + * down, but we are still initializing the system. ?Pages are given directly
> + * to the page allocator, no bootmem metadata is updated because it is gone.
> + */
> +void __init free_bootmem_late(unsigned long addr, unsigned long size)
> +{
> + ? ? ? unsigned long start, end;
> +
> + ? ? ? kmemleak_free_part(__va(addr), size);
> +
> + ? ? ? start = PFN_UP(addr);
> + ? ? ? end = PFN_DOWN(addr + size);
> +
> + ? ? ? totalram_pages += free_bootmem_pages(start, end, NULL);
> +}
> +
> +/**
> ?* reserve_bootmem_node - mark a page range as reserved
> ?* @pgdat: node the range resides on
> ?* @physaddr: starting address of the range
> --
> 1.5.6.5
>
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