Re: [Xen-devel] [PATCH 00/04] Kexec / Kdump: Release 20061122 (xen-unstable-12502)

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

Hi Magnus,

On Wed, 2006-11-22 at 16:10 +0900, Magnus Damm wrote:
> [PATCH 00/04] Kexec / Kdump: Release 20061122 (xen-unstable-12502)

I've been playing a bit more and found a problem.

You define a per CPU variable crash_notes and on crash you loop over
NR_CPUS and clear the notes for CPUS which don't exist. Unfortunately
the percpu regions for CPUs which aren't physically present is returned
to the heap on boot (see percpu_free_unused_areas) -- this means that
you zero out heap pages on crash :-(

You need to use num_{possible,present,online}_cpus() in
machine_crash_kexec() and kexec_get_cpu() instead of NR_CPUS.

Cheers,
Ian.



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