Messages in this thread | | | Subject | Re: sparsemem panic in 2.6.17-rc5-mm1 and -mm2 | From | Rusty Russell <> | Date | Wed, 07 Jun 2006 15:36:25 +1000 |
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On Tue, 2006-06-06 at 21:58 -0700, Andrew Morton wrote: > On Wed, 7 Jun 2006 09:43:55 +0900 > KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > > On Tue, 6 Jun 2006 00:27:58 -0700 > > Andrew Morton <akpm@osdl.org> wrote: > > > > > > > > I tried sparsemem on my little x86 box here. Boots OK, after fixing up the > > > kswapd_init() patch (below). > > > > > > I'm wondering why I have 4k of highmem: > > > > > > > Could you show /proc/iomem of your 4k HIGHMEM box ? > > Does 4k HIGHMEM exist only when SPARSEMEM is selected ? > > Turns out that my 4 kbyte highmem zone (at least, as reported in > /proc/meminfo) is due to > > vdso-randomize-the-i386-vdso-by-moving-it-into-a-vma.patch
Thanks for this report, Andrew!
Yes, MAXMEM is reduced by one page in the patch, taking into account that kernel memory tops out at __FIXADDR_TOP, not 0xFFFFFFFF. AFAICT this is in fact a bugfix, which becomes more important when __FIXADDR_TOP can be moved to create a larger memory hole (as for hypervisors).
You now have 1 page more memory available in your system. Use it wisely.
I'm sure Gerd will slap me if I'm wrong on this. Here's the patch fragment:
-#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE) +#define MAXMEM (__FIXADDR_TOP-__PAGE_OFFSET-__VMALLOC_RESERVE)
Cheers, Rusty. -- ccontrol: http://ccontrol.ozlabs.org
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