Re: 2.4.16 memory badness (reproducible)

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <Pine.LNX.4.21.0112111850090.1164-100000@localhost.localdomain>
By author:    Hugh Dickins <hugh@veritas.com>
In newsgroup: linux.dev.kernel
> 
> I believe this error comes, not from a (genuine or mistaken) shortage
> of free memory, but from shortage or fragmentation of vmalloc's virtual
> address space.  Does patch below (to 2.4.17-pre4-aa1 since I think that's
> what you tried last; easily adaptible to other trees) doubling vmalloc's
> address space (on your 1GB machine or larger) make any difference?
> Perhaps there's a vmalloc leak and this will only delay the error.
> 
> Hugh
> 
> --- 1704aa1/arch/i386/kernel/setup.c	Tue Dec 11 15:22:53 2001
> +++ linux/arch/i386/kernel/setup.c	Tue Dec 11 19:01:37 2001
> @@ -835,7 +835,7 @@
>  /*
>   * 128MB for vmalloc and initrd
>   */
> -#define VMALLOC_RESERVE	(unsigned long)(128 << 20)
> +#define VMALLOC_RESERVE	(unsigned long)(256 << 20)
>  #define MAXMEM		(unsigned long)(-PAGE_OFFSET-VMALLOC_RESERVE)
>  #ifdef CONFIG_HIGHMEM_EMULATION
>  #define ORDER_DOWN(x)	((x >> (MAX_ORDER-1)) << (MAX_ORDER-1))
> 

Well, for one thing it will screw over just about every Linux boot
loader in existence if you are using an initrd.  You need my boot
protocol 2.03 patch *plus* a 2.03 compliant boot loader (e.g. SYSLINUX
1.65-pre2 or later) if you apply this change to a 1 GB or larger
machine.

	-hpa
-- 
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"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>