Messages in this thread | | | From | pageexec@freemail ... | Date | Wed, 28 Nov 2007 00:01:57 +0200 | Subject | Re: [PATCH 1/1] mm: Prevent dereferencing non-allocated per_cpu variables |
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On 27 Nov 2007 at 13:50, travis@sgi.com wrote:
> Change loops controlled by 'for (i = 0; i < NR_CPUS; i++)' to use > 'for_each_possible_cpu(i)' when there's a _remote possibility_ of > dereferencing a non-allocated per_cpu variable involved.
actually, it's not that remote, it happens every time NR_CPUS > num_possible_cpus(). i ran into this myself on a dual core box with NR_CPUS=4. due to my rewrite of the i386 per-cpu segment handling, i actually got a NULL deref where the vanilla kernel would be accessing the area of [__per_cpu_start, __per_cpu_end] for each non-possible CPU (which doesn't crash per se but is still not correct somehow i think).
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