[PATCH v4] kexec: Make a pair of map and unmap reserved pages when kdump fails to start
holzheu at linux.vnet.ibm.com
Tue Jul 14 11:10:16 PDT 2015
On Tue, 14 Jul 2015 10:09:20 -0400
Vivek Goyal <vgoyal at redhat.com> wrote:
> On Fri, Jul 10, 2015 at 11:14:06AM +0200, Michael Holzheu wrote:
> > What about the following patch:
> > ---
> > diff --git a/kernel/kexec.c b/kernel/kexec.c
> > index 7a36fdc..7837c4e 100644
> > --- a/kernel/kexec.c
> > +++ b/kernel/kexec.c
> > @@ -1236,10 +1236,68 @@ int kexec_load_disabled;
> > static DEFINE_MUTEX(kexec_mutex);
> > +static int __kexec_load(unsigned long entry, unsigned long nr_segments,
> > +
> > +failure_unmap_mem:
> I don't like this tag "failure_unmap_mem". We are calling this both
> in success path as well as failure path. So why not simply call it "out".
Since the code is better readable now, I'm fine with "out" :-)
> > + if (flags & KEXEC_ON_CRASH)
> > + crash_unmap_reserved_pages();
> > + kimage_free(image);
> Now kimage_free() is called with kexec_mutex held. Previously that was
> not the case. I hope that's not a problem.
Yes, I noticed that. But also in the original code there is already
one spot where kimage_free() is called under lock:
* In case of crash, new kernel gets loaded in reserved region. It is
* same memory where old crash kernel might be loaded. Free any
* current crash dump kernel before we corrupt it.
if (flags & KEXEC_FILE_ON_CRASH)
Therefore I thought it should be ok.
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