Re: 2.6.16-rc1-mm3

[Eric Dumazet]

Andy Whitcroft a écrit :
> Eric Dumazet wrote:
> > The NULL choice was maybe wrong. We might need more than one page to
> > fully catch all accesses. Something like 32KB.
>
> The crash behavoir is handy to catch that the problem exists, and is
> very cheap (0 cost) at run time.  However, once its known I think we
> need something more targetted to allow tracking of the cause.  Perhaps
> we could set the offset thingy to -1 or something and simply do
> something like the following in per_cpu():
>
> 	if (__per_cpu_offset[i] == -1)
> 		BUG();
> 	else
> 		*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu])

Yes we can set __per_cpu_offset[not_possible_cpu] to 0, because 
[__per_cpu_start,__per_cpu_end) is in init section and should be discarded in 
free_initmem(). I'm not sure if the freed virtual space can later be reused.

Eric
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