linux-kernel - Re: [patch] mm: node-setup agnostic free

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Message-ID: <86802c440804281211y3e512286k1d3f9f7e157b4957@mail.gmail.com>
Date:	Mon, 28 Apr 2008 12:11:29 -0700
From:	"Yinghai Lu" <yhlu.kernel@...il.com>
To:	"Johannes Weiner" <hannes@...urebad.de>
Cc:	"Ingo Molnar" <mingo@...e.hu>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, jbarnes@...tuousgeek.org,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
Subject: Re: [patch] mm: node-setup agnostic free_bootmem()

On Mon, Apr 28, 2008 at 9:54 AM, Johannes Weiner <hannes@...urebad.de> wrote:
> Hi Yinghai,
>
>
>
>  "Yinghai Lu" <yhlu.kernel@...il.com> writes:
>
>  > On Sun, Apr 27, 2008 at 5:40 PM, Ingo Molnar <mingo@...e.hu> wrote:
>  >>
>  >>  * Johannes Weiner <hannes@...urebad.de> wrote:
>  >>
>  >>  > > so i very much agree that your changes are cleaner, i just wanted to
>  >>  > > have one that has all the fixes included.
>  >>  >
>  >>  > I had planned this to be another patch because there are more then one
>  >>  > boundary check I wanted to tighten.  I can merge them though if you
>  >>  > like.
>  >>
>  >>  no, better to have them in separate patches.
>  >>
>  >>  > > Would you like to post a patch against current -git or should i
>  >>  > > extract the cleaner reserve_bootmem() from your previous patch?
>  >>  >
>  >>  > I just moved and have only sporadic internet access and free time
>  >>  > slots available.  Would be nice if you could do it!
>  >>
>  >>  sure, find the merged patch below, against latest -git, boot-tested on
>  >>  x86. Is this what you had in mind?
>  >>
>  >>         Ingo
>  >>
>  >>  ---------------->
>  >>  Subject: mm: node-setup agnostic free_bootmem()
>  >>  From: Johannes Weiner <hannes@...urebad.de>
>  >>  Date: Wed, 16 Apr 2008 13:36:31 +0200
>  >>
>  >>  Make free_bootmem() look up the node holding the specified address
>  >>  range which lets it work transparently on single-node and multi-node
>  >>  configurations.
>  >>
>  >>  If the address range exceeds the node range, it well be marked free
>  >>  across node boundaries, too.
>  >>
>  >>  Signed-off-by: Johannes Weiner <hannes@...urebad.de>
>  >>  CC: Andi Kleen <andi@...stfloor.org>
>  >>  CC: Yinghai Lu <yhlu.kernel@...il.com>
>  >>  CC: Yasunori Goto <y-goto@...fujitsu.com>
>  >>  CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>  >>  CC: Christoph Lameter <clameter@....com>
>  >>  CC: Andrew Morton <akpm@...ux-foundation.org>
>  >>  Signed-off-by: Ingo Molnar <mingo@...e.hu>
>  >>  ---
>  >>   mm/bootmem.c |   27 +++++++++++++++++++++++++--
>  >>   1 file changed, 25 insertions(+), 2 deletions(-)
>  >>
>  >>  Index: linux-x86.q/mm/bootmem.c
>  >>  ===================================================================
>  >>  --- linux-x86.q.orig/mm/bootmem.c
>  >>  +++ linux-x86.q/mm/bootmem.c
>  >>  @@ -493,8 +493,31 @@ int __init reserve_bootmem(unsigned long
>  >>   void __init free_bootmem(unsigned long addr, unsigned long size)
>  >>   {
>  >>         bootmem_data_t *bdata;
>  >>  -       list_for_each_entry(bdata, &bdata_list, list)
>  >>  -               free_bootmem_core(bdata, addr, size);
>  >>  +       unsigned long pos = addr;
>  >>  +       unsigned long partsize = size;
>  >>  +
>  >>  +       list_for_each_entry(bdata, &bdata_list, list) {
>  >>  +               unsigned long remainder = 0;
>  >>  +
>  >>  +               if (pos < bdata->node_boot_start)
>  >>  +                       continue;
>  >>  +
>  >>  +               if (PFN_DOWN(pos + partsize) > bdata->node_low_pfn) {
>  >>  +                       remainder = PFN_DOWN(pos + partsize) - bdata->node_low_pfn;
>  >>  +                       partsize -= remainder;
>  >>  +               }
>  >>  +
>  >>  +               free_bootmem_core(bdata, pos, partsize);
>  >>  +
>  >>  +               if (!remainder)
>  >>  +                       return;
>  >>  +
>  >>  +               pos = PFN_PHYS(bdata->node_low_pfn + 1);
>  >>  +       }
>  >>  +       printk(KERN_ERR "free_bootmem: request: addr=%lx, size=%lx, "
>  >>  +                       "state: pos=%lx, partsize=%lx\n", addr, size,
>  >>  +                       pos, partsize);
>  >>  +       BUG();
>  >>   }
>  >>
>  >>   unsigned long __init free_all_bootmem(void)
>  >>
>  >
>  > it will not work with cross nodes.
>  >
>  > for example: node 0: 0-2g, 4-6g, node1: 2-4g, 6-8g.
>  > and if ramdisk sit cross 2G boundary. you will only free the range
>  > before 2g.
>
>  Yes, you stated that several times but this is not a technical argument:
>  These setups are afaik not yet supported by the kernel at all.  And you
>  could not explain the node layout with the patch that implements support
>  for these configurations.

I looked at Suresh's patch, and it still only has one bdata for one node.

YH
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